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Abstract Background: Previous studies of aerobic exercise have found lower sensor accuracy during exercise. Whether or not resistance exercise would also be associated with lower sensor accuracy has not yet been examined. This study sought to investigate the accuracy of continuous glucose monitoring sensor values at rest, during aerobic exercise, and during resistance exercise. Subjects and Methods: Twelve individuals with type 1 diabetes performed 45 min of aerobic exercise, resistance exercise, or no exercise/rest followed by 60 min of recovery while monitored by continuous glucose monitoring systems. Results: Sensors underestimated plasma glucose to the greatest extent during rest (-1.29±1.39 mmol/L, P<0.001) and resistance exercise (-0.71±1.35 mmol/L, P<0.001) and least during aerobic exercise (-0.11±1.71 mmol/L, P=0.416). Conclusions: Optimal accuracy observed with aerobic exercise might arise from augmented blood flow better equilibrating plasma and interstitial fluid or from the combination of systematic sensor underestimation and sensor lag time. [ABSTRACT FROM AUTHOR]

Objective: To determine the effects of exercise order on acute glycemic responses in individuals with type 1 diabetes performing both aerobic and resistance exercise in the same session.Research Design and Methods: Twelve physically active individuals with type 1 diabetes (HbA(1c) 7.1 ± 1.0%) performed aerobic exercise (45 min of running at 60% V(O(2peak))) before 45 min of resistance training (three sets of eight, seven different exercises) (AR) or performed the resistance exercise before aerobic exercise (RA). Plasma glucose was measured during exercise and for 60 min after exercise. Interstitial glucose was measured by continuous glucose monitoring 24 h before, during, and 24 h after exercise.Results: Significant declines in blood glucose levels were seen in AR but not in RA throughout the first exercise modality, resulting in higher glucose levels in RA (AR = 5.5 ± 0.7, RA = 9.2 ± 1.2 mmol/L, P = 0.006 after 45 min of exercise). Glucose subsequently decreased in RA and increased in AR over the course of the second 45-min exercise bout, resulting in levels that were not significantly different by the end of exercise (AR = 7.5 ± 0.8, RA = 6.9 ± 1.0 mmol/L, P = 0.436). Although there were no differences in frequency of postexercise hypoglycemia, the duration (105 vs. 48 min) and severity (area under the curve 112 vs. 59 units ⋅ min) of hypoglycemia were nonsignificantly greater after AR compared with RA.Conclusions: Performing resistance exercise before aerobic exercise improves glycemic stability throughout exercise and reduces the duration and severity of postexercise hypoglycemia for individuals with type 1 diabetes. [ABSTRACT FROM AUTHOR]

Background: Previous trials have evaluated the effects of aerobic training alone and of resistance training alone on glycemic control in type 2 diabetes, as assessed by hemoglobin A1c values. However, none could assess incremental effects of combined aerobic and resistance training compared with either type of exercise alone.Objective: To determine the effects of aerobic training alone, resistance training alone, and combined exercise training on hemoglobin A1c values in patients with type 2 diabetes.Design: Randomized, controlled trial.Setting: 8 community-based facilities.Patients: 251 adults age 39 to 70 years with type 2 diabetes. A negative result on a stress test or clearance by a cardiologist, and adherence to exercise during a 4-week run-in period, were required before randomization.Interventions: Aerobic training, resistance training, or both types of exercise (combined exercise training). A sedentary control group was included. Exercise training was performed 3 times weekly for 22 weeks (weeks 5 to 26 of the study).Measurements: The primary outcome was the change in hemoglobin A1c value at 6 months. Secondary outcomes were changes in body composition, plasma lipid values, and blood pressure.Results: The absolute change in the hemoglobin A1c value in the combined exercise training group compared with the control group was -0.51 percentage point (95% CI, -0.87 to -0.14) in the aerobic training group and -0.38 percentage point (CI, -0.72 to -0.22) in the resistance training group. Combined exercise training resulted in an additional change in the hemoglobin A1c value of -0.46 percentage point (CI, -0.83 to -0.09) compared with aerobic training alone and -0.59 percentage point (CI, -0.95 to -0.23) compared with resistance training alone. Changes in blood pressure and lipid values did not statistically significantly differ among groups. Adverse events were more common in the exercise groups.Limitations: The generalizability of the results to patients who are less adherent to exercise programs is uncertain. The participants were not blinded, and the total duration of exercise was greater in the combined exercise training group than in the aerobic and resistance training groups.Conclusion: Either aerobic or resistance training alone improves glycemic control in type 2 diabetes, but the improvements are greatest with combined aerobic and resistance training. ClinicalTrials.gov registration number: NCT00195884. [ABSTRACT FROM AUTHOR]

Context: Exercise is widely perceived to be beneficial for glycemic control and weight loss in patients with type 2 diabetes. However, clinical trials on the effects of exercise in patients with type 2 diabetes have had small sample sizes and conflicting results.Objective: To systematically review and quantify the effect of exercise on glycosylated hemoglobin (HbA(1c)) and body mass in patients with type 2 diabetes.Data Sources: Database searches of MEDLINE, EMBASE, Sport Discuss, Health Star, Dissertation Abstracts, and the Cochrane Controlled Trials Register for the period up to and including December 2000. Additional data sources included bibliographies of textbooks and articles identified by the database searches.Study Selection: We selected studies that evaluated the effects of exercise interventions (duration >/=8 weeks) in adults with type 2 diabetes. Fourteen (11 randomized and 3 nonrandomized) controlled trials were included. Studies that included drug cointerventions were excluded.Data Extraction: Two reviewers independently extracted baseline and postintervention means and SDs for the intervention and control groups. The characteristics of the exercise interventions and the methodological quality of the trials were also extracted.Data Synthesis: Twelve aerobic training studies (mean [SD], 3.4 [0.9] times/week for 18 [15] weeks) and 2 resistance training studies (mean [SD], 10 [0.7] exercises, 2.5 [0.7] sets, 13 [0.7] repetitions, 2.5 [0.4] times/week for 15 [10] weeks) were included in the analyses. The weighted mean postintervention HbA(1c) was lower in the exercise groups compared with the control groups (7.65% vs 8.31%; weighted mean difference, -0.66%; P<.001). The difference in postintervention body mass between exercise groups and control groups was not significant (83.02 kg vs 82.48 kg; weighted mean difference, 0.54; P =.76).Conclusion: Exercise training reduces HbA(1c) by an amount that should decrease the risk of diabetic complications, but no significantly greater change in body mass was found when exercise groups were compared with control groups. [ABSTRACT FROM AUTHOR]

Context: Although many studies suggest that physical activity may reduce risk of type 2 diabetes, the role of moderate-intensity activity such as walking is not well understood.Objectives: To examine the relationship of total physical activity and incidence of type 2 diabetes in women and to compare the benefits of walking vs vigorous activity as predictors of subsequent risk of type 2 diabetes.Design and Setting: The Nurses' Health Study, a prospective cohort study that included detailed data for physical activity from women surveyed in 11 US states in 1986, with updates in 1988 and 1992.Participants: A total of 70,102 female nurses aged 40 to 65 years who did not have diabetes, cardiovascular disease, or cancer at baseline (1986).Main Outcome Measure: Risk of type 2 diabetes by quintile of metabolic equivalent task (MET) score, based on time spent per week on each of 8 common physical activities, including walking.Results: During 8 years of follow-up (534, 928 person-years), we documented 1419 incident cases of type 2 diabetes. After adjusting for age, smoking, alcohol use, history of hypertension, history of high cholesterol level, and other covariates, the relative risks (RRs) of developing type 2 diabetes across quintiles of physical activity (least to most) were 1.0, 0.77, 0.75, 0.62, and 0.54 (P for trend <.001); after adjusting for body mass index (BMI), RRs were 1.0, 0.84, 0.87, 0.77, and 0.74 (P for trend = .002). Among women who did not perform vigorous activity, multivariate RRs of type 2 diabetes across quintiles of MET score for walking were 1.0, 0.91,0.73, 0.69, and 0.58 (P for trend <.001). After adjusting for BMI, the trend remained statistically significant (RRs were 1.0, 0.95, 0.80, 0.81, 0.74; P for trend = .01). Faster usual walking pace was independently associated with decreased risk. Equivalent energy expenditures from walking and vigorous activity resulted in comparable magnitudes of risk reduction.Conclusions: Our data suggest that greater physical activity level is associated with substantial reduction in risk of type 2 diabetes, including physical activity of moderate intensity and duration. [ABSTRACT FROM AUTHOR]

Although physical activity (PA) is a key element in the prevention and management of type 2 diabetes, many with this chronic disease do not become or remain regularly active. High-quality studies establishing the importance of exercise and fitness in diabetes were lacking until recently, but it is now well established that participation in regular PA improves blood glucose control and can prevent or delay type 2 diabetes, along with positively affecting lipids, blood pressure, cardiovascular events, mortality, and quality of life. Structured interventions combining PA and modest weight loss have been shown to lower type 2 diabetes risk by up to 58% in high-risk populations. Most benefits of PA on diabetes management are realized through acute and chronic improvements in insulin action, accomplished with both aerobic and resistance training. The benefits of physical training are discussed, along with recommendations for varying activities, PA-associated blood glucose management, diabetes prevention, gestational diabetes mellitus, and safe and effective practices for PA with diabetes-related complications. [ABSTRACT FROM AUTHOR]

Background: The primary aim of this study was to compare the efficacy of three physical activity (PA) behavioural intervention strategies in a sample of adults with type 2 diabetes.Method/design: Participants (N = 287) were randomly assigned to one of three groups consisting of the following intervention strategies: (1) standard printed PA educational materials provided by the Canadian Diabetes Association [i.e., Group 1/control group)]; (2) standard printed PA educational materials as in Group 1, pedometers, a log book and printed PA information matched to individuals' PA stage of readiness provided every 3 months (i.e., Group 2); and (3) PA telephone counseling protocol matched to PA stage of readiness and tailored to personal characteristics, in addition to the materials provided in Groups 1 and 2 (i.e., Group 3). PA behaviour measured by the Godin Leisure Time Exercise Questionnaire and related social-cognitive measures were assessed at baseline, 3, 6, 9, 12 and 18-months (i.e., 6-month follow-up). Clinical (biomarkers) and health-related quality of life assessments were conducted at baseline, 12-months, and 18-months. Linear Mixed Model (LMM) analyses will be used to examine time-dependent changes from baseline across study time points for Groups 2 and 3 relative to Group 1.Discussion: ADAPT will determine whether tailored but low-cost interventions can lead to sustainable increases in PA behaviours. The results may have implications for practitioners in designing and implementing theory-based physical activity promotion programs for this population.Clinical Trials Registration: ClinicalTrials.gov identifier: NCT00221234. [ABSTRACT FROM AUTHOR]

Background: The optimal criteria to select individuals with type 1 diabetes mellitus (T1D) and albuminuric or normoalbuminuric diabetic kidney disease (DKD), who are at risk of rapid kidney function decline, for clinical trials are unclear., Methods: This study analyzed data from the Preventing Early Renal Loss in Diabetes (PERL) clinical trial, which investigated whether allopurinol slowed kidney function decline in persons with T1D and early-to-moderate DKD. Rates of iohexol GFR (iGFR) and estimated GFR (eGFR) decline during the three-year study were compared by linear mixed effect regression between participants enrolled based on a history of moderately or severely increased albuminuria (N=394) and those enrolled based on a recent history of rapid kidney function decline (≥3 ml/min/1.73 m2/year) in the absence of a history of albuminuria (N=124). The association between baseline albuminuria and iGFR/eGFR decline during the trial was also evaluated., Results: Rates of eGFR decline during the trial were higher in participants with a history of albuminuria than in those with a history of rapid kidney function decline (-3.56 [95% confidence intervals {CI} -3.17, -3.95] versus -2.35 [95% CI: -1.86, -2.84] ml/min/1.73 m2/year, p=0.001). Results were similar for iGFR decline, although the difference was not significant (p=0.07). Within the history of albuminuria group, the rate of eGFR decline was -5.30 (95% CI -4.52, -6.08) ml/min/1.73m2/year in participants with severely increased albuminuria as compared to -2.97 (95% CI 2.44, -3.50) and -2.32 (95% CI -1.61, -3.03) ml/min/1.73m2/year in those with moderately increased or normal/mildly increased albuminuria at baseline (p<0.001)., Conclusions: Severely increased albuminuria at screening is a powerful criterion for selecting persons with T1D at high risk of kidney function decline. A history of rapid eGFR decline without a history of albuminuria is less effective for this purpose but it can still identify individuals with T1D who will lose kidney function more rapidly than expected from physiological aging., Clinical Trail Registration: ClinicalTrials.gov, NCT02017171., (Copyright © 2024 by the American Society of Nephrology.)

Aims/hypothesis: This study aimed to describe the relationship between breastfeeding episodes and maternal glucose levels, and to assess whether this differs with closed-loop vs open-loop (sensor-augmented pump) insulin therapy., Methods: Infant-feeding diaries were collected at 6 weeks, 12 weeks and 24 weeks postpartum in a trial of postpartum closed-loop use in 18 women with type 1 diabetes. Continuous glucose monitoring (CGM) data were used to identify maternal glucose patterns within the 3 h of breastfeeding episodes. Generalised mixed models adjusted for breastfeeding episodes in the same woman, repeat breastfeeding episodes, carbohydrate intake, infant age at time of feeding and early pregnancy HbA 1c . This was a secondary analysis of data collected during a randomised trial (ClinicalTrials.gov registration no. NCT04420728)., Results: CGM glucose remained above 3.9 mmol/l in the 3 h post-breastfeeding for 93% (397/427) of breastfeeding episodes. There was an overall decrease in glucose at nighttime within 3 h of breastfeeding (1.1 mmol l -1 h -1 decrease on average; p=0.009). A decrease in nighttime glucose was observed with open-loop therapy (1.2 ± 0.5 mmol/l) but was blunted with closed-loop therapy (0.4 ± 0.3 mmol/l; p<0.01, open-loop vs closed-loop)., Conclusions/interpretation: There is a small decrease in glucose after nighttime breastfeeding that usually does not result in maternal hypoglycaemia; this appears to be blunted with the use of closed-loop therapy., (© 2024. The Author(s).)

Aim: To evaluate the effect on type 2 diabetes remission of short-term intensive metabolic intervention consisting of frequent dietary, exercise and diabetes management coaching, metformin and fixed-ratio insulin degludec/liraglutide., Methods: In a multicentre open-label randomized controlled trial, insulin-naïve participants within 5 years of diabetes diagnosis were assigned to a 16-week remission intervention regimen or standard care, and followed for relapse of diabetes and sustained remission for an additional year after stopping glucose-lowering drugs., Results: A total of 159 participants aged 57 ± 10 years, with diabetes duration 2.6 ± 1.5 years, body mass index 33.5 ± 6.5 kg/m 2 , and glycated haemoglobin (HbA1c) level 53 ± 7 mmol/mol were randomized and analysed (79 intervention, 80 control). At the end of the 16-week intervention period, compared to controls, intervention participants achieved lower HbA1c levels (40 ± 4 vs. 51 ± 7 mmol/mol; p < 0.0001), and lost more weight (3.3 ± 4.4% vs. 1.9 ± 3.0%; p = 0.02). There was a lower hazard of diabetes relapse overall in the intervention group compared to controls (hazard ratio 0.63, 95% confidence interval [CI] 0.45, 0.88; p = 0.007), although this was not sustained over time. Remission rates in the intervention group were not significantly higher than in the control group at 12 weeks (17.7% vs. 12.5%, relative risk [RR] 1.42, 95% CI 0.67, 3.00; p = 0.36) or at 52 weeks (6.3% vs. 3.8%, RR 1.69, 95% CI 0.42, 6.82) following the intervention period., Conclusions: An intensive remission-induction intervention including fixed-ratio insulin degludec/liraglutide reduced the risk of type 2 diabetes relapse within 1 year without sustained remission., (© 2024 The Author(s). Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.)

Objectives: Closed-loop insulin delivery has the potential to offer women with type 1 diabetes a break from intense diabetes self-care efforts postpartum. Our aim in this study was to explore the views and opinions of hybrid closed-loop users and their partners in the first 24 weeks postpartum., Methods: This qualitative study was embedded in a controlled study of women with type 1 diabetes randomized to closed-loop insulin delivery (MiniMed™ 670G or 770G) or sensor-augmented pump use for 1 to 11 weeks 6 days postpartum, with all on closed-loop delivery from 12 to 24 weeks postpartum. Semistructured interviews were conducted with 16 study participants and their partners at 12 and 24 weeks postpartum. Thematic analyses were used to examine participants' and partners' experiences., Results: Participants' positive perceptions of closed-loop use related to reduced hypoglycemia, in contrast to previous experiences with nonautomated insulin delivery. These perceptions were balanced against frustrations with the system, allowing blood glucose levels to be higher than desired. Closed-loop use did not influence infant feeding choice, but infant feeding and care impacted participants' diabetes management. Partners expressed uncertainty about the closed loop taking away control from participants who were highly skilled with diabetes self-management., Conclusions: Participants reported that closed-loop insulin delivery resulted in less time spent in hypoglycemia when compared with the previously used nonautomated delivery. Yet, participants desired a greater understanding of the workings of the closed-loop algorithm. Our study provides potential users with realistic expectations about the experience with the MiniMed 670G or 770G closed-loop system in the postpartum period., (Copyright © 2024 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.)

Older adults are at elevated risk of heat-related mortality due to age-associated declines in thermoregulatory and cardiovascular function. However, the inter-individual factors that exacerbate physiological heat strain during heat exposure remain unclear, making it challenging to identify more heat-vulnerable subgroups. We therefore explored factors contributing to inter-individual variability in physiological responses of older adults exposed to simulated hot weather. Thirty-seven older adults (61-80 years, 16 females) rested for 8 h in 31 and 36 °C (45% relative humidity). Core (rectal) temperature, heart rate (HR), HR variability, mean arterial pressure (MAP), and cardiac autonomic responses to standing were measured at baseline and end-exposure. Bootstrapped least absolute shrinkage and selection operator regression was used to evaluate whether variation in these responses was related to type 2 diabetes (T2D, n  = 10), hypertension ( n  = 18), age, sex, body morphology, habitual physical activity levels, and/or heat-acclimatization. T2D was identified as a predictor of end-exposure HR (with vs. without: 13 beats/min (bootstrap 95% confidence interval: 6, 23)), seated MAP (-7 mmHg (-18, 1)), and the systolic pressure response to standing (20 mmHg (4, 36)). HR was also influenced by sex (female vs. male: 8 beats/min (1, 16)). No other predictors were identified. The inter-individual factors explored did not meaningfully contribute to the variation in body temperature responses in older adults exposed to simulated indoor overheating. By contrast, cardiovascular responses were exacerbated in females and individuals with T2D. These findings improve understanding of how inter-individual differences contribute to heat-induced physiological strain in older persons., Competing Interests: None declared.

Purpose: Maximum heart rate (HRmax) is commonly used to estimate exercise intensity. Since direct measurement of HRmax is not always practical, prediction equations were developed. However, most equations have not been properly validated in older adults at low and high risk of cardiovascular disease (CVD). We sought to: 1) assess the accuracy of commonly used equations to predict HRmax amongst adults at low and high CVD risk and, 2) determine if SuperLearner (SL) modeling combining base machine algorithms could improve HRmax prediction., Methods: A total of 1208 participants (61.6 ± 7.3 years; 62.7% male) were included. HRmax was measured during a maximal cardiorespiratory exercise test. Predicted HRmax was estimated using the following published equations: Fox, Astrand, Tanaka, Gelish and Gulati, and a SL model. Bland-Altman analyses as well as performance indicators such as root mean squared error (RMSE) and Lin's CCC were performed., Results: All predicted HRmax-derived equations were positively associated with measured HRmax (women; r = 0.31: men; r = 0.46, p ≤ 0.001) but to a greater extent using a SL model (women; r = 0.47: men; r = 0.59, p ≤ 0.001). Overall, all equations tended to overestimate measured HRmax, with a RMSE which varied between 10.4 and 12.3 bpm. Although the SL model outperformed other equations, with no significant difference between measured and predicted HRmax, RMSE remained high (11.3 bpm). Lack of accuracy was mainly observed among adults with low aerobic fitness and with CVD risk factors, such as obesity, diabetes, and hypertension., Conclusions: We showed that commonly used equations and the SL model have insufficient accuracy to predict HRmax among adults. The performance of the prediction equations varied considerably according to the population clinical characteristics such as the presence of CVD risk factors or a low aerobic fitness., Competing Interests: Conflict of Interest and Funding Source: The authors have no funding sources to declare. The authors have no conflicts of interest to disclose., (Copyright © 2024 by the American College of Sports Medicine.)

Foot immersion and neck cooling are recommended cooling strategies for protecting heat-vulnerable persons during heat waves. While we recently showed that these strategies do not limit core temperature increases in older adults during prolonged heat exposure, we did observe small reductions in heart rate. Expanding on these findings, we examined the effects of foot immersion with and without neck cooling on cardiac autonomic function. Seventeen adults (9 females; 65-81 years) underwent 3 randomized, 6-hour exposures to 38°C and 35% relative humidity with: no cooling (control), foot immersion (20°C water), or foot immersion with a wet towel (20°C) around the neck. Cardiac autonomic responses were measured at baseline and end-exposure. These included heart rate variability, cardiac and systolic blood pressure responses to standing, indexed via the 30:15 ratio and supine-to-standing systolic pressure change, respectively, and baroreflex sensitivity during repeated sit-to-stand maneuvers. The 30:15 ratio was 0.04 [95% CI: 0.01, 0.07] greater with foot immersion and neck cooling (1.08 (0.04)) relative to control (1.04 (0.06); P=0.018). Similarly, standing systolic pressure was elevated 9 [0, 17] mm Hg with foot immersion and neck cooling (P=0.043). That said, neither difference remained statistically significant after adjusting for multiplicity (Padjusted≥0.054). No differences in 30:15 ratio or standing systolic pressure were observed with foot immersion alone, while heart rate variability and baroreflex sensitivity were unaffected by either cooling intervention. While foot immersion with neck cooling potentially improved cardiac autonomic responses in older adults exposed to simulated indoor overheating, these effects were small and of questionable clinical importance.

The brain derived-neurotrophic factor (BDNF) Val66Met polymorphism causes functional changes in BDNF, and is associated with obesity and some psychiatric disorders, but its relationship to health-related quality of life (HRQoL) remains unknown. This study examined, in youth with obesity, whether carriers of the BDNF Val66met polymorphism Met-alleles (A/A or G/A) differed from noncarriers (G/G) on HRQoL. The participants were 187 adolescents with obesity. Ninety-nine youth were carriers of the homozygous Val/Val (G/G) alleles, and 88 were carriers of the Val/Met (G/A) or Met/Met (A/A) alleles. Blood samples were drawn in the morning after an overnight fast for genotyping. HRQoL was measured using the Pediatric-Quality of Life core version. Compared to carriers of the Val66Met Val (G/G) alleles, carriers of the Met-Alleles reported significantly higher physical -HRQoL (p = 0.02), school-related HRQoL, (p = 0.05), social-related HRQoL (p = 0.05), and total HRQoL (p = 0.03), and a trend for Psychosocial-HRQoL. Research is needed to confirm our findings and determine whether carriers of the BDNF Val66Met homozygous Val (G/G) alleles may be at risk of diminished HRQoL, information that can influence interventions in a high-risk population of inactive youth with obesity., (© 2024 The Author(s). Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Type 2 diabetes (T2D) is associated with reduced whole body sweating during exercise-heat stress. However, it is unclear if this impairment is related to exercise intensity and whether it occurs uniformly across body regions. We evaluated whole body (direct calorimetry) and local (ventilated-capsule technique; chest, back, forearm, thigh) sweat rates in physically active men with type 2 diabetes [T2D; aged 59 (7) yr; V̇o 2peak 32.3 (7.6) mL·kg -1 ·min -1 ; n = 26; HbA 1c 5.1%-9.1%] and without diabetes [Control; aged 61 (5) yr; V̇o 2peak 37.5 (5.4) mL·kg -1 ·min -1 ; n = 26] during light- (∼40% V̇o 2peak ), moderate- (∼50% V̇o 2peak ), and vigorous- (∼65% V̇o 2peak ) intensity exercise (elicited by fixing metabolic heat production at ∼150, 200, 250 W·m -2 , respectively) in 40°C, ∼17% relative humidity. Whole body sweating was ∼11% (T2D: Control mean difference [95% confidence interval]: -37 [-63, -12] g·m -2 ·h -1 ) and ∼13% (-50 [-76, -25] g·m -2 ·h -1 ) lower in the T2D compared with the Control group during moderate- and vigorous- ( P ≤ 0.001) but not light-intensity exercise (-21 [-47, 4] g·m -2 ·h -1 ; P = 0.128). Consequently, the diabetes-related reductions in whole body sweat rate were 2.3 [1.6, 3.1] times greater during vigorous relative to light exercise ( P < 0.001). Furthermore, these diabetes-related impairments in local sweating were region-specific during vigorous-intensity exercise (group × region interaction: P = 0.024), such that the diabetes-related reduction in local sweat rate at the trunk (chest, back) was 2.4 [1.2, 3.7] times greater than that at the limbs (thigh, arm). In summary, when assessed under hot, dry conditions, diabetes-related impairments in sweating are exercise intensity-dependent and greater at the trunk compared with the limbs. NEW & NOTEWORTHY This study evaluates the influence of exercise intensity on decrements in whole body sweating associated with type 2 diabetes. Furthermore, it investigates whether diabetes-related sweating impairments were exhibited uniformly or heterogeneously across body regions. We found that whole body sweating was attenuated in the type 2 diabetes group relative to control participants during moderate- and vigorous-intensity exercise but not light-intensity exercise; impairments were largely mediated by reduced sweating at the trunk rather than the limbs.

To protect vulnerable populations during heat waves, public health agencies recommend maintaining indoor air temperature below ∼24-28 °C. While we recently demonstrated that maintaining indoor temperatures ≤26 °C mitigates the development of hyperthermia and cardiovascular strain in older adults, the cellular consequences of prolonged indoor heat stress are poorly understood. We therefore evaluated the cellular stress response in 16 adults (six females) aged 66-78 years during 8 h rest in ambient conditions simulating homes maintained at 22 °C (control) and 26 °C (indoor temperature upper limit proposed by health agencies), as well as non-air-conditioned domiciles during hot weather and heat waves (31 and 36 °C, respectively; all 45% relative humidity). Western blot analysis was used to assess changes in proteins associated with the cellular stress response (autophagy, apoptosis, acute inflammation, and heat shock proteins) in peripheral blood mononuclear cells harvested prior to and following exposure. Following 8 h exposure, no cellular stress response-related proteins differed significantly between the 26 and 22 °C conditions (all, P  ≥ 0.056). By contrast, autophagy-related proteins were elevated following exposure to 31 °C (p62: 1.5-fold; P  = 0.003) and 36 °C (LC3-II, LC3-II/I, p62; all ≥2.0-fold; P  ≤ 0.002) compared to 22 °C. These responses were accompanied by elevations in apoptotic signaling in the 31 and 36 °C conditions (cleaved-caspase-3: 1.8-fold and 3.7-fold, respectively; P  ≤ 0.002). Furthermore, HSP90 was significantly reduced in the 36 °C compared to 22 °C condition (0.7-fold; P  = 0.014). Our findings show that older adults experience considerable cellular stress during prolonged exposure to elevated ambient temperatures and support recommendations to maintain indoor temperatures ≤26 °C to prevent physiological strain in heat-vulnerable persons., Competing Interests: No conflict of interest, financial or otherwise, are declared by the author(s).

Type 2 diabetes (T2D) is associated with worsening age-related impairments in heat loss, causing higher core temperature during exercise. We evaluated whether these thermoregulatory impairments occur with altered serum protein responses to heat stress by measuring cytoprotection, inflammation, and tissue damage biomarkers in middle-aged-to-older men (50-74 years) with ( n  = 16) and without ( n  = 14) T2D following exercise in 40°C. There were no changes in irisin, klotho, HSP70, sCD14, TNF-α, and IL-6, whereas NGAL (+539 pg/mL, p  = 0.002) and iFABP (+250 pg/mL, p  < 0.001) increased similarly across groups. These similar response patterns occurred despite elevated core temperature in individuals with T2D, suggesting greater heat vulnerability., Competing Interests: The authors declare there are no competing interests.

Older adults are at greater risk of heat-related morbidity and mortality during heat waves, which is commonly linked to impaired thermoregulation. However, little is known about the influence of increasing age on the relation between thermal strain and perceptual responses during daylong heat exposure. We evaluated thermal and perceptual responses in 20 young (19-31 yr) and 39 older adults (20 with hypertension and/or type 2 diabetes; 61-78 yr) resting in the heat for 9 h (heat index: 37°C). Body core and mean skin temperature areas under the curve (AUC, hours 0-9 ) were assessed as indicators of cumulative thermal strain. Self-reported symptoms (68-item environmental symptoms questionnaire) and mood disturbance (40-item profile of mood states questionnaire) were assessed at end-heating (adjusted for prescores). Body core temperature AUC was 2.4°C·h [1.0, 3.7] higher in older relative to young adults ( P < 0.001), whereas mean skin temperature AUC was not different (-0.5°C·h [-4.1, 3.2] P = 0.799). At end-heating, self-reported symptoms were not different between age groups (0.99-fold [0.80, 1.23], P = 0.923), with or without adjustment for body core or mean skin temperature AUC (both P ≥ 0.824). Mood disturbance was 0.93-fold [0.88, 0.99] lower in older, relative to young adults ( P = 0.031). Older adults with and without chronic health conditions experienced similar thermal strain, yet those with these conditions reported lower symptom scores and mood disturbance compared with young adults and their age-matched counterparts (all P ≤ 0.026). Although older adults experienced heightened thermal strain during the 9-h heat exposure, they did not experience greater self-reported symptoms or mood disturbance relative to young adults. NEW & NOTEWORTHY Despite experiencing greater cumulative thermal strain during 9 h of passive heat exposure, older adults reported similar heat-related symptoms and lower mood disturbance than young adults. Furthermore, self-reported symptoms and mood disturbance were lower in older adults with common age-associated health conditions than young adults and healthy age-matched counterparts. Perceptual responses to heat in older adults can underestimate their level of thermal strain compared with young adults, which may contribute to their increased heat vulnerability.

Background: Health agencies recommend that homes of heat-vulnerable occupants (e.g., older adults) be maintained below 24-28°C to prevent heat-related mortality and morbidity. However, there is limited experimental evidence to support these recommendations., Objective: To aid in the development of evidence-based guidance on safe indoor temperatures for temperate continental climates, we evaluated surrogate physiological outcomes linked with heat-related mortality and morbidity in older adults during simulated indoor overheating., Methods: Sixteen older adults [six women; median age: 72 y, interquartile range (IQR): 70-73 y; body mass index: 24.6   ( IQR :   22.1 - 27.0 )   kg / m 2 ] from the Ottawa, Ontario, Canada, region (warm summer continental climate) completed four randomized, 8-h exposures to conditions experienced indoors during hot weather in continental climates (e.g., Ontario, Canada; 64 participant exposures). Ambient conditions simulated an air-conditioned environment (22°C; control), proposed indoor temperature upper limits (26°C), and temperatures experienced in homes without air-conditioning (31°C and 36°C). Core temperature (rectal) was monitored as the primary outcome; based on previous recommendations, between-condition differences > 0.3 ° C were considered clinically meaningful., Results: Compared with 22°C, core temperature was elevated to a meaningful extent in 31°C [ + 0 . 7 ° C ; 95% confidence interval (CI): 0.5, 0.8] and 36°C ( + 0 . 9 ° C ; 95% CI: 0.8, 1.1), but not 26°C ( + 0 . 2 ° C , 95% CI: 0.0, 0.3). Increasing ambient temperatures were also associated with elevated heart rate and reduced arterial blood pressure and heart rate variability at rest, as well as progressive impairments in cardiac and blood pressure responses to standing from supine., Discussion: Core temperature and cardiovascular strain were not appreciably altered following 8-h exposure to 26°C but increased progressively in conditions above this threshold. These data support proposals for the establishment of a 26°C indoor temperature upper limit for protecting vulnerable occupants residing in temperate continental climates from indoor overheating. https://doi.org/10.1289/EHP13159.

Objective: This study aimed to evaluate the efficacy of closed-loop insulin delivery postpartum., Research Design and Methods: In this open-label, randomized controlled trial, postpartum individuals with type 1 diabetes were randomized to hybrid closed-loop insulin delivery with the MiniMed 670G/770G system in automode or sensor-augmented pump therapy in the first 12-weeks postpartum followed by a continuation phase with closed-loop insulin delivery for all until 24 weeks postpartum., Results: Eighteen participants (mean ± SD age 32 ± 3.5 years, diabetes duration 22 ± 7.3 years, and early pregnancy HbA1c 52 ± 6.8 mmol/mol [6.9 ± 0.9%]) completed 24 weeks of postpartum follow-up. In the randomized phase, percent time in range 70-180 mg/dL (3.9-10 mmol/L) did not differ between groups (79.2 ± 8.7% vs. 78.2 ± 6.0%; P = 0.41). Participants randomized to closed-loop insulin delivery spent less time <70 mg/dL (3.9 mmol/L) and <54 mg/dL (3.0 mmol/L) (1.7 ± 0.8% vs. 5.5 ± 3.3% [P < 0.001] and 0.3 ± 0.2% vs. 1.1 ± 0.9% [P = 0.008]). Time >180 mg/dL (10 mmol/L) was not different between groups (18.7 ± 8.8% vs. 15.9 ± 7.7%; P = 0.21). In the continuation phase, those initially randomized to sensor-augmented pump therapy had less time <70 mg/dL after initiation of closed-loop insulin delivery (5.5 ± 3.3% vs. 3.3 ± 2.2%; P = 0.039). The closed-loop group maintained similar glycemic metrics in both study phases. There were no episodes of diabetic ketoacidosis or severe hypoglycemia in the randomized or continuation phase in either group., Conclusions: Women randomized to closed-loop insulin delivery postpartum had less hypoglycemia than those randomized to sensor-augmented pump therapy. There were no safety concerns. These findings are reassuring for use of closed-loop insulin delivery postpartum because of its potential to reduce hypoglycemia., (© 2023 by the American Diabetes Association.)

Aim: Non-surgical options for inducing type 2 diabetes remission are limited. We examined whether remission can be achieved by combining lifestyle approaches and short-term intensive glucose-lowering therapy., Methods: In this trial, 160 patients with type 2 diabetes on none to two diabetes medications other than insulin were randomised to (a) an intervention comprising lifestyle approaches, insulin glargine/lixisenatide and metformin, or (b) standard care. Participants with glycated haemoglobin (HbA1c) <7.3% (56 mmol/mol) at 12 weeks were asked to stop diabetes medications and were followed for an additional 52 weeks. The primary outcome was diabetes relapse defined as HbA1c ≥6.5% (48 mmol/mol) at 24 weeks or thereafter, capillary glucose ≥10 mmol/L on ≥50% of readings, or use of diabetes medications, analysed as time-to-event. Main secondary outcomes included complete or partial diabetes remission at 24, 36, 48 and 64 weeks defined as HbA1c <6.5% (48 mmol/mol) off diabetes medications since 12 weeks after randomisation. A hierarchical testing strategy was applied., Results: The intervention significantly reduced the hazard of diabetes relapse by 43% (adjusted hazard ratio 0.57, 95% confidence interval 0.40-0.81; p = .002). Complete or partial diabetes remission was achieved in 30 (38.0%) intervention group participants versus 16 (19.8%) controls at 24 weeks and 25 (31.6%) versus 14 (17.3%) at 36 weeks [relative risk 1.92 (95% confidence interval 1.14-3.24) and 1.83 (1.03-3.26), respectively]. The relative risk of diabetes remission in the intervention versus control group was 1.88 (1.00-3.53) at 48 weeks and 2.05 (0.98-4.29) at 64 weeks., Conclusions: A 12-week intensive intervention comprising insulin glargine/lixisenatide, metformin and lifestyle approaches can induce remission of diabetes., (© 2023 The Authors. Diabetes, Obesity and Metabolism published by John Wiley & Sons Ltd.)

Heat waves can cause dangerous elevations in body temperature that can compromise cellular function and increase the risk of heat stroke and major cardiovascular events. Visiting a cooling center or other air-conditioned location is commonly recommended by health agencies to protect heat-vulnerable older persons but the associated cellular effects remain underexplored. We evaluated cellular stress responses in peripheral blood mononuclear cells (PBMC) from 19 older adults [71 (SD 2) yr; 9 females] before and after a 9-h heat exposure [40.3°C and 9.3% relative humidity (RH)], with participants moved to a cool room (∼23°C) for hours 5 and 6 (cooling group). Responses were compared with 17 older adults [72 (4) yr; 7 females] who remained in the heat for the entire 9 h (control group). Changes in proteins associated with autophagy, apoptotic signaling, acute inflammation, and the heat shock response (HSR) were assessed via Western blot. Although both groups experienced similar elevations in physiological strain before the cooling center intervention, brief cooling resulted in stark albeit transient reductions in core temperature and heart rate. At end-exposure, autophagy proteins LC3-II and p62 were elevated 1.9-fold [95% CI: 1.2, 2.8] and 2.3-fold [1.4, 3.8], respectively, in the control group relative to cooling group. This was paired with a 2.8-fold [1.6, 4.7] greater rise in apoptotic protein cleaved-caspase-3 in the control group compared with the cooling group. Our findings indicate that 2 h of ambient cooling midway through a 9-h simulated heat wave may preserve autophagy and mitigate heat-induced cellular stress in older adults. NEW & NOTEWORTHY Heat waves can lead to dangerous elevations in body temperature, increasing the risk of life-threatening health conditions. Visiting a cooling center or other air-conditioned location is commonly recommended to protect heat-vulnerable older persons, although the effects on the cellular stress response remain unknown. We found that 2 h of ambient cooling midway through a 9 h simulated heat wave preserves autophagy, a vital cellular survival mechanism, and mitigates accompanying pathways of cellular stress in older adults.

Aging is associated with an elevated risk of heat-related mortality and morbidity, attributed, in part, to declines in thermoregulation. However, comparisons between young and older adults have been limited to brief exposures (1-4 h), which may not adequately reflect the duration or severity of the heat stress experienced during heat waves. We therefore evaluated physiological responses in 20 young (19-31 yr; 10 females) and 39 older (61-78 yr; 11 females) adults during 9 h of rest at 40°C and 9% relative humidity. Whole body heat exchange and storage were measured with direct calorimetry during the first 3 h and final 3 h. Core temperature (rectal) was monitored continuously. The older adults stored 88 kJ [95% confidence interval (CI): 29, 147] more heat over the first 3 h of exposure ( P = 0.006). Although no between-group differences were observed after 3 h [young: 37.6°C (SD 0.2°C) vs. older: 37.7°C (0.3°C); P = 0.216], core temperature was elevated by 0.3°C [0.1, 0.4] (adjusted for baseline) in the older group at hour 6 [37.6°C (0.2°C) vs. 37.9°C (0.2°C); P < 0.001] and by 0.2°C [0.0, 0.3] at hour 9 [37.7°C (0.3°C) vs. 37.8°C (0.3°C)], although the latter comparison was not significant after multiplicity correction ( P = 0.061). Our findings indicate that older adults sustain greater increases in heat storage and core temperature during daylong exposure to hot dry conditions compared with their younger counterparts. This study represents an important step in the use of ecologically relevant, prolonged exposures for translational research aimed at quantifying the physiological and health impacts of hot weather and heat waves on heat-vulnerable populations. NEW & NOTEWORTHY We found greater increases in body heat storage and core temperature in older adults than in their younger counterparts during 9 h of resting exposure to hot dry conditions. Furthermore, the age-related increase in core temperature was exacerbated in older adults with common heat-vulnerability-linked health conditions (type 2 diabetes and hypertension). Impairments in thermoregulatory function likely contribute to the increased risk of heat-related illness and injury seen in older adults during hot weather and heat waves.

With rising global temperatures, heat-related mortality is increasing, particularly among older adults. Although this is often attributed to declines in thermoregulatory function, little is known regarding the effect of age on the cellular processes associated with mitigating heat-induced cytotoxicity. We compared key components of the cellular stress response in 19 young (19-31 yr; 10 female) and 37 older adults (61-78 yr; 10 female) during 9 h of heat exposure (40°C, 9% relative humidity). Mean body temperature (T body ) was calculated from core and skin temperatures. Changes in proteins associated with autophagy, apoptotic signaling, acute inflammation, and the heat shock response were assessed via Western blot in peripheral blood mononuclear cells harvested before and after exposure. T body increased by 1.5 (SD 0.3)°C and 1.7 (0.3)°C in the young and older adults, respectively. We observed similar elevations in autophagy-related proteins (LC3-II and LC3-II/I) in young and older adults (both P ≥ 0.121). However, the older adults displayed signs of autophagic dysfunction, evidenced by a 3.7-fold [95% CI: 2.4, 5.6] greater elevation in the selective autophagy receptor p62 ( P < 0.001). This was paired with elevations in apoptotic responses, with a 1.7-fold [1.3, 2.3] increase in cleaved caspase-3 in the older relative to young adults ( P < 0.001). Older adults also exhibited diminished heat shock protein 90 responses (0.7-fold [0.5, 0.9] vs. young, P = 0.011) and, at any given level of thermal strain (T body area under the curve), elevated tumor necrosis factor-α (1.5-fold [1.0, 2.5] vs. young, P = 0.008). Attenuated autophagic responses may underlie greater vulnerability to heat-induced cellular injury in older adults. NEW & NOTEWORTHY We demonstrate for the first time that peripheral blood mononuclear cells from older adults exhibit signs of autophagic impairments during daylong (9 h) heat exposure relative to their younger counterparts. This was paired with greater apoptotic signaling and inflammatory responses, and an inability to stimulate components of the heat shock response. Thus, autophagic dysregulation during prolonged heat exposure may contribute to age-related heat vulnerability during hot weather and heat waves.

Background: Health agencies, including the U.S. Centers for Disease Control and Prevention and the World Health Organization, recommend that heat-vulnerable older adults without home air-conditioning should visit cooling centers or other air-conditioned locations (e.g., a shopping mall) during heat waves. However, experimental evidence supporting the effectiveness of brief air-conditioning is lacking., Objective: We evaluated whether brief exposure to an air-conditioned environment, as experienced in a cooling center, was effective for limiting physiological strain in older adults during a daylong laboratory-based heat wave simulation., Methods: Forty adults 64-79 years of age underwent a 9-h simulated heat wave (heat index: 37°C) with (cooling group, n = 20 ) or without (control group, n = 20 ) a cooling intervention consisting of 2-h rest in an air-conditioned room ( ∼ 23 ° C , hours 5-6). Core and skin temperatures, whole-body heat exchange and storage, cardiovascular function, and circulating markers of acute inflammation were assessed., Results: Core temperature was 0.8°C (95% CI: 0.6, 0.9) lower in the cooling group compared with the control group at the end of the cooling intervention ( p < 0.001 ; hour 6), and it remained 0.3°C (95% CI: 0.2, 0.4) lower an hour after returning to the heat ( p < 0.001 ; hour 7). Despite this, core temperatures in each group were statistically equivalent at hours 8 and 9, within ± 0.3 ° C ( p ≤ 0.005 ). Cooling also acutely reduced demand on the heart and improved indices of cardiovascular autonomic function ( p ≤ 0.021 ); however, these outcomes were not different between groups at the end of exposure ( p ≥ 0.58 )., Discussion: Brief air-conditioning exposure during a simulated heat wave caused a robust but transient reduction in core temperature and cardiovascular strain. These findings provide important experimental support for national and international guidance that cooling centers are effective for limiting physiological strain during heat waves. However, they also show that the physiological impacts of brief cooling are temporary, a factor that has not been considered in guidance issued by health agencies. https://doi.org/10.1289/EHP11651.

Exercise plays an important role in the management of diabetes and is associated with many benefits such as decreased morbidity and mortality. For people exhibiting signs and symptoms of cardiovascular disease, pre-exercise medical clearance is warranted; however, requiring broad screening requirements can lead to unnecessary barriers to initiating an exercise program. Robust evidence supports the promotion of both aerobic and resistance training, with evidence emerging on the importance of reducing sedentary time. For people with type 1 diabetes, there are special considerations, including hypoglycemia risk and prevention, exercise timing (including prandial status), and differences in glycemic responses based on biological sex., (© 2023 by the American Diabetes Association.)

Objective: To examine the proportion of participants with poor sleep quality, evaluate the associations between sleep quality and anthropometric and cardiometabolic health markers, and evaluate the effect of high intensity interval training (HIIT) and continuous aerobic exercise training (CAET) on sleep quality in polycystic ovary syndrome (PCOS)., Design: Secondary analysis of a pilot randomized controlled trial., Patients: Women with PCOS aged 18-40 years., Measurements: The Pittsburgh Sleep Quality Index (PSQI) was measured at baseline and following a 6-month exercise intervention. A PSQI score >5 indicates poor sleep. Linear regression was used to evaluate the associations between PSQI score and anthropometric and cardiometabolic health markers, and the effect of exercise training on these associations., Results: Thirty-four participants completed the PSQI at baseline, and 29 postintervention: no-exercise control (n = 9), HIIT (n = 12) and CAET (n = 8). At baseline, 79% had poor sleep quality. Baseline PSQI score was positively correlated with body mass index, waist circumference, body weight, haemoglobin A1c and insulin resistance. Mean PSQI score changes were -0.4 (SD 1.1), -0.7 (SD 0.6) and -0.5 (SD 0.9) for control, HIIT and CAET, respectively. For HIIT participants, change in PSQI score was associated with changes in body weight (B = .27, 95% CI 0.10-0.45) and waist circumference (B = .09, 95% CI 0.02-0.17)., Conclusion: Most participants had poor sleep quality which was associated with poorer anthropometric and cardiometabolic health markers. There were no statistically significant changes in PSQI score with exercise training. With HIIT training, decreases in the sleep efficiency score were associated with reductions in body weight and waist circumference. Further studies are needed to determine the effect of exercise training on sleep quality., (© 2023 The Authors. Clinical Endocrinology published by John Wiley & Sons Ltd.)

Context: Resistance exercise training (strength training) and aerobic exercise training are both recommended for people with type 1 diabetes, but it is unknown whether adding resistance exercise provides incremental benefits in people with this condition who already perform aerobic exercise regularly., Objective: This work aimed to evaluate the incremental effect of resistance training on glycated hemoglobin A1c (HbA1c), fitness, body composition, and cardiometabolic risk factors in aerobically active people with type 1 diabetes., Methods: The Resistance Exercise in Already-active Diabetic Individuals (READI) trial (NCT00410436) was a 4-center, randomized, parallel-group trial. After a 5-week run-in period with diabetes management optimization, 131 aerobically active individuals with type 1 diabetes were randomly assigned to resistance exercise (n = 71, intervention-INT) or control (n = 60, CON) for 22 additional weeks. Both groups maintained their aerobic activities and were provided dietary counseling throughout. Exercise training was 3 times per week at community-based facilities. The primary outcome was HbA1c, and secondary outcomes included fitness (peak oxygen consumption, muscle strength), body composition (anthropometrics, dual-energy x-ray absorptiometry, computed tomography), and cardiometabolic risk markers (lipids, apolipoproteins). Assessors were blinded to group allocation., Results: There were no significant differences in HbA1c change between INT and CON. Declines in HbA1c (INT: 7.75 ± 0.10% [61.2 ± 1.1 mmol/mol] to 7.55 ± 0.10% [59 ± 1.1 mmol/mol]; CON: 7.70 ± 0.11% [60.7 ± 1.2 mmol/mol] to 7.57 ± 0.11% [59.6 ± 1.3 mmol/mol]; intergroup difference in change -0.07 [95% CI, -0.31 to 0.18]). Waist circumference decreased more in INT than CON after 6 months (P = .02). Muscular strength increased more in INT than in CON (P < .001). There were no intergroup differences in hypoglycemia or any other variables., Conclusion: Adding resistance training did not affect glycemia, but it increased strength and reduced waist circumference, in aerobically active individuals with type 1 diabetes., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

New Findings: What is the central question of this study? Is the impairment in heat dissipation during exercise observed in men with type 2 diabetes related to glycaemic control (indexed by glycated haemoglobin; haemoglobin A 1c )? What is the main finding and its importance? No association was found between haemoglobin A 1c (range: 5.1-9.1%) and whole-body heat loss in men with type 2 diabetes during exercise in the heat. However, individuals with elevated haemoglobin A 1c exhibited higher body core temperature and heart rate responses. Thus, while haemoglobin A 1c is not associated with heat loss per se, it may still have important implications for physiological strain during exercise., Abstract: Type 2 diabetes is associated with a reduced capacity to dissipate heat. It is unknown whether this impairment is related to glycaemic control (indexed by glycated haemoglobin; haemoglobin A 1c ) is unknown. We evaluated the association between haemoglobin A 1c and whole-body heat loss (via direct calorimetry), body core temperature, and heart rate in 26 physically active men with type 2 diabetes (43-73 years; HbA 1c 5.1-9.1%) during exercise at increasing rates of metabolic heat production (∼150, 200, 250 W m -2 ) in the heat (40°C, ∼17% relative humidity). Haemoglobin A 1c was not associated with whole-body heat loss (P = 0.617), nor the increase in core temperature from pre-exercise (P = 0.347). However, absolute core temperature and heart rate were elevated ∼0.2°C (P = 0.014) and ∼6 beats min -1 (P = 0.049), respectively, with every percentage point increase in haemoglobin A 1c . Thus, while haemoglobin A 1c does not appear to modify diabetes-related reductions in capacity for heat dissipation, it may still have important implications for physiological strain during exercise-heat stress., (© 2022 The Authors. Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Current labor demographics are changing, with the number of older adults increasingly engaged in physically demanding occupations expected to continually rise, which are often performed in the heat. Given an age-related decline in whole-body heat loss, older adults are at an elevated risk of developing heat injuries that may be exacerbated by hypertension (HTN) and type 2 diabetes (T2D). Elevated irisin production may play a role in mitigating the excess oxidative stress and acute inflammation associated with physically demanding work in the heat. However, the effects of HTN and T2D on this response remain unclear. Therefore, we evaluated serum irisin before and after 3-h of moderate intensity exercise (metabolic rate: 200 W/m 2 ) and at the end of 60-min of post-exercise recovery in a temperate (wet-bulb globe temperature (WBGT) 16 °C) and high-heat stress (WBGT 32 °C) environment in 12 healthy older men (mean ± SD; 59 ± 4 years), 10 men with HTN (60 ± 4 years), and 9 men with T2D (60 ± 5 years). Core temperature (T co ) was measured continuously. In the heat, total exercise duration was significantly lower in older men with HTN and T2D (both, p ≤ 0.049). Despite T co not being different between groups, T co was higher in the hot compared to the temperate condition for all groups (p < 0.001). Similarly, serum irisin concentrations did not differ between groups under either condition but were elevated relative to the temperate condition during post-exercise and end-recovery in the heat (+93.9 pg/mL SEM 26 and + 70.5 pg/mL SEM 38 respectively; both p ≤ 0.014). Thus, our findings indicate similar irisin responses in HTN and T2D compared to healthy, age-matched controls, despite reduced exercise tolerance during prolonged exercise in the heat. Therefore, older workers with HTN and T2D may exhibit greater cellular stress during prolonged exercise in the heat, underlying greater vulnerability to heat-induced cellular injury., Competing Interests: Declaration of competing interest No conflict of interest, financial or otherwise, are declared by the author(s)., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Although many studies have assumed variability reflects variance caused by exercise training, few studies have examined whether interindividual differences in trainability are present following exercise training. The present individual participant data (IPD) meta-analysis sought to: (1) investigate the presence of interindividual differences in trainability for cardiorespiratory fitness (CRF), waist circumference, and body mass; and (2) examine the influence of exercise training and potential moderators on the probability that an individual will experience clinically important differences. The IPD meta-analysis combined data from 1879 participants from eight previously published randomized controlled trials. We implemented a Bayesian framework to: (1) test the hypothesis of interindividual differences in trainability by comparing variability in change scores between exercise and control using Bayes factors; and (2) compare posterior predictions of control and exercise across a range of moderators (baseline body mass index (BMI) and exercise duration, intensity, amount, mode, and adherence) to estimate the proportions of participants expected to exceed minimum clinically important differences (MCIDs) for all three outcomes. Bayes factors demonstrated a lack of evidence supporting a high degree of variance attributable to interindividual differences in trainability across all three outcomes. These findings indicate that interindividual variability in observed changes are likely due to measurement error and external behavioural factors, not interindividual differences in trainability. Additionally, we found that a larger proportion of exercise participants were expected to exceed MCIDs compared with controls for all three outcomes. Moderator analyses identified that larger proportions were associated with a range of factors consistent with standard exercise theory and were driven by mean changes. Practitioners should prescribe exercise interventions known to elicit large mean changes to increase the probability that individuals will experience beneficial changes in CRF, waist circumference and body mass., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Baseline risk variables and visit-to-visit variability (VV) of systolic blood pressure (SBP), HbA 1c , serum creatinine, and uric acid (UA) are potential risk markers of kidney function decline in type 1 diabetes., Methods: Post-hoc analysis of a double-blind randomized placebo-controlled clinical trial investigating allopurinol's effect on iohexol-derived glomerular filtration rate (iGFR) in type 1 diabetes with elevated UA. Primary outcome was iGFR change over three years. Linear regression with backwards selection of baseline clinical variables was performed to identify an optimized model forecasting iGFR change. Furthermore, VVs of SBP, HbA 1c , serum creatinine, and UA were calculated using measurements from the run-in period; thereafter assessed by linear regression, with iGFR change as the dependent variable., Results: 404 participants were included in the primary analyses. In the optimized baseline variable model, higher HbA 1c , SBP, iGFR, albuminuria, and heart rate, and mineralocorticoid receptor antagonist prescription were associated with greater iGFR decline. Higher VV of SBP was associated with greater iGFR decline (adjusted β (ml/min/1.73 m 2 /50 % increase): -0.79, p = 0.01)., Conclusions: We identified several risk markers for faster iGFR decline in a high-risk population with type 1 diabetes. While further research is needed, our results indicate possible new and clinically feasible measures to risk stratify for DKD in type 1 diabetes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: There are well-recognized benefits of behavioral interventions that include exercise for children and adolescents with obesity. However, such behavioral weight management programs may precipitate unintended consequences. It is unclear if different exercise modalities impact eating behaviors differently in youth with obesity., Objectives: The purpose of this study was to examine the effects of aerobic, resistance, and combined aerobic and resistance exercise training on eating attitudes and behaviors (uncontrolled eating, restrained eating, emotional eating, external eating and food craving) among adolescents with overweight and obesity., Methods: N  = 304 (70% female) adolescents with overweight and obesity participated in the 6-month Healthy Eating Aerobic and Resistance Training in Youth (HEARTY) randomized controlled trial. All participants were inactive post-pubertal adolescents (15.6 ± 1.4 years) with a mean BMI = 34.6 ± 4.5 kg/m 2 . The Food Craving Inventory (food cravings), Dutch Eating Behavior Questionnaire (restrained eating, emotional eating, external eating), and the Three-Factor Eating Questionnaire (uncontrolled eating) were used to assess eating attitudes and behaviors., Results: All exercise groups showed within-group decreases in external eating and food cravings. Participants randomized to the Combined training group and were more adherent showed the greatest improvements in eating behaviors and cravings., Conclusions: A 6-month exercise intervention produced improvements in disordered eating behaviors and food cravings, but effects may be gender and modality-specific. Findings highlight the need to tailor exercise intervention to participant characteristics for the promotion of healthier eating and weight management outcomes in youth with obesity., Clinical Trial Registration # and Date: ClinicalTrials.Gov NCT00195858, September 12, 2005., Competing Interests: The author declares that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported., (© 2022 The Authors. Obesity Science & Practice published by World Obesity and The Obesity Society and John Wiley & Sons Ltd.)

Objectives: Individuals with type 2 diabetes should engage in ≥150 min of moderate- to vigorous-intensity physical activity (MVPA) weekly, but most do not meet this guideline. Understanding how social determinants correlate with physical activity in adults with type 2 diabetes may improve development and delivery of physical activity interventions. This study aimed to explore associations between objectively measured MVPA with sociodemographic characteristics in adults with type 2 diabetes., Methods: Cross-sectional data from cycles 1 through 5 of the Canadian Health Measures Survey were analyzed. Participants (N=876) 20 to 79 years of age with type 2 diabetes and ≥4 days of valid activity monitor wear were included. Proportions with 95% confidence intervals for objectively measured MVPA were compared according to sociodemographic characteristics. Ordinal logistic regression was used. Secondary outcomes included light-intensity physical activity, screen time and proportion of activity monitor wear time spent sedentary., Results: Only 15.5% of women and 26.2% of men met Diabetes Canada physical activity guidelines, and approximately 75% of activity monitor wear time was spent in a sedentary state. Higher odds of achieving low levels of physical activity were observed among women who were former or current smokers (odds ratio [OR], 4.51; p<0.001), and among men who were ≥65 years of age (OR, 2.92; p<0.001), of middle (OR, 2.20; p<0.05) and lowest (OR, 3.06; p<0.05) income tertiles and current or former smokers (OR, 3.01; p<0.05)., Conclusions: Sociodemographic factors are strongly associated with levels of MVPA in adults with type 2 diabetes. Sociodemographic information should be routinely collected by clinicians and used to inform more tailored and effective interventions for this patient population., (Copyright © 2022. Published by Elsevier Inc.)

Aims: To compare the efficacy and safety of antihyperglycemic agents, taken in combination with metformin, for the treatment of type 2 diabetes mellitus (T2DM)., Methods: A previous 2016 comprehensive search of Ovid MEDLINE, PubMed, and Cochrane CENTRAL was updated to October 2018, and a systematic review and network meta-analysis (NMA) was conducted. Randomized controlled trials (RCTs) of patients with T2DM taking an antihyperglycemic agent in combination with metformin were included. Bayesian NMA was performed to assess the relative efficacy and safety of the antihyperglycemic classes., Results: In total, 204 RCTs were included, which assessed the efficacy and safety of eight antihyperglycemic drug classes (i.e., sulfonylureas, meglitinides, alpha-glucosidase inhibitors, thiazolidinediones, basal and biphasic insulin, dipeptidyl peptidase 4 inhibitors, glucagon-like-peptide-1 receptor agonists and sodium-glucose cotransport-2 inhibitors). All drug classes significantly reduced haemoglobin A1c (HbA1c) compared to metformin monotherapy (mean reduction from 0.50 to 0.92). The drug classes varied in their relative effects on hypoglycemia, body weight, body mass index, systolic and diastolic blood pressure, total cholesterol, high and low density lipoprotein cholesterol, and the classes had differing safety profiles on total adverse events, urogenital adverse events, heart failure, serious adverse events, and withdraw due to adverse events., Conclusions: All eight antihyperglycemic drug classes, taken in combination with metformin, reduced HbA1c levels; however, the effects of the agents on other outcomes varied among the classes., (© 2021 John Wiley & Sons Ltd.)