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Aims/hypothesis: The relationship between pre-meal insulin type, exercise timing and the risk of postprandial exercise-induced hypoglycaemia in people living with type 1 diabetes is unknown. We aimed to evaluate the effects of exercise timing (60 vs 120 min post meal) and different insulin types (aspart vs ultra-rapid aspart) on hypoglycaemic risk., Methods: This was a four-way crossover randomised trial including 40 individuals with type 1 diabetes using multiple daily injections (mean HbA 1c 56 mmol/mol [7.4%]). Participants, who were recruited from the Montreal Clinical Research Institute, undertook 60 min cycling sessions (60% of V ˙ O 2 peak ) after breakfast (60 min [EX60min] or 120 min [EX120min] post meal) with 50% of their usual insulin dose (aspart or ultra-rapid aspart). Eligibility criteria included age ≥18 years old, clinical diagnosis of type 1 diabetes for at least 1 year and HbA 1c ≤80 mmol/mol (9.5%). Participants were allocated using sequentially numbered, opaque sealed envelopes. Participants were masked to their group assignment, and each participant was allocated a unique identification number to ensure anonymisation. The primary outcome was change in blood glucose levels between exercise onset and nadir., Results: Prior to exercise onset, time spent in hyperglycaemia was lower for EX60min vs EX120min (time >10.0 mmol/l: 56.6% [1.2-100%] vs 78.0% [52.7-97.9%]; p<0.001). The glucose reduction between exercise onset and nadir was less pronounced with EX60min vs EX120min (-3.8±2.7 vs -4.7±2.5 mmol/l; p<0.001). A similar number of hypoglycaemic events occurred during both exercise timings. Blood glucose between exercise onset and nadir decreased less with ultra-rapid aspart compared with aspart (-4.1±2.3 vs -4.4±2.8 mmol/l; p=0.037). While a similar number of hypoglycaemic events during exercise were observed, less post-exercise hypoglycaemia occurred with ultra-rapid aspart (n=0, 0%, vs n=15, 38%; p=0.003). No interactions between insulin types and exercise timings were found., Conclusions/interpretation: EX60min blunted the pre-exercise glucose increase following breakfast and was associated with a smaller glucose reduction during exercise. Ultra-rapid aspart led to a smaller blood glucose reduction during exercise and might be associated with diminished post-exercise hypoglycaemia., Trial Registration: ClinicalTrials.gov NCT03659799 FUNDING: This study was funded by Novo Nordisk Canada., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Aims: This study aimed to explore sleep pattern, physical fitness and the barriers to physical activity (PA) during Ramadan observance among non-fasting individuals with type 1 diabetes (T1D) METHODS: Sixty-one patients with T1D (29 women, 32 men), who were non-fasting, completed pre- and during-Ramadan questionnaires, incorporating assessments such as the Barriers to PA (BAPAD1), Pittsburgh Sleep Quality Index (PSQI), and International Physical Activity Questionnaire (IPAQ)., Results: During Ramadan, BAPAD1 scores exhibited a non-significant increase (p=0.378). Primary barriers encompassed hypoglycaemia risk, work schedules, diabetes control, and fatigue. The PSQI scores demonstrated a significant increase (p<0.01), revealing a deteriorated sleep quality. Sleep duration decreased by 58 minutes (p<0.01), was associated with later bedtimes and awakenings. PA levels notably decreased (p=0.042), particularly in vigorous activities (p=0.017), while sedentary time witnessed a significant increase (p=0.008)., Conclusion: Ramadan observance did not affect barriers to PA in individuals with T1D despite alteration of sleep pattern and PA practice. lifestyle alterations induced by Ramadan observance significantly impact individuals with T1D who are not fasting, resulting in reduced PA, shortened sleep duration, and increased sedentary time., (Copyright © 2024. Published by Elsevier Inc.)

Purpose: The present study aimed to characterize the exercise-induced neuromuscular fatigue and its possible links with cerebral and muscular oxygen supply and utilization to provide mechanistic insights into the reduced exercise capacity characterizing patients with end-stage renal disease (ESRD)., Methods: Thirteen patients with ESRD and thirteen healthy males (CTR group) performed a constant-force sustained isometric contraction at 50% of their maximal voluntary isometric contraction (MVC) until exhaustion. Quadriceps muscle activation during exercise was estimated from vastus lateralis, vastus medialis, and rectus femoris EMG. Central and peripheral fatigue were quantified via changes in pre- to postexercise quadriceps voluntary activation (ΔVA) and quadriceps twitch force (ΔQ tw,pot ) evoked by supramaximal electrical stimulation, respectively. To assess cerebral and muscular oxygenation, throughout exercise, near-infrared spectroscopy allowed investigation of changes in oxyhemoglobin (∆O 2 Hb), deoxyhemoglobin (∆HHb), and total hemoglobin (∆THb) in the prefrontal cortex and in the vastus lateralis muscle., Results: ESRD patients demonstrated lower exercise time to exhaustion than that of CTR (88.8 ± 15.3 s and 119.9 ± 14.6 s, respectively, P < 0.01). Following the exercise, MVC, Q tw,pot , and VA reduction were similar between the groups (P > 0.05). There was no significant difference in muscle oxygenation (∆O 2 Hb) between the two groups (P > 0.05). Cerebral and muscular blood volume (∆THb) and oxygen extraction (∆HHb) were significantly blunted in the ESRD group (P < 0.05). A significant positive correlation was observed between time to exhaustion and cerebral blood volume (∆THb) in both groups (r 2  = 0.64, P < 0.01)., Conclusions: These findings support cerebral hypoperfusion as a factor contributing to the reduction in exercise capacity characterizing ESRD patients., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: In this study we explore the impact of postprandial exercise timing (morning vs evening) on glycemia in individuals with type 1 diabetes (T1D) during short all-out sprints on a cycle ergometer., Methods: Ten healthy physically sedentary male (n=7) and female (n=3) volunteers with type 1 diabetes, 22.8±2.8 years of age, and with a diabetes duration of 9.7±5.5 years and glycated hemoglobin level of 8.6±1.2%, underwent comprehensive screening and assessment of their physical health and fitness status before study participation, under the guidance of a physician. Each participant underwent 2 postprandial exercise sessions on separate days: the first in the morning at 8:00 AM and second in the evening at 8:00 PM, both conducted 60 minutes after a standardized meal., Results: Morning exercise showed a less pronounced reduction in plasma glucose (PG) levels compared with evening exercise (-2.01±1.24 vs -3.56±1.6 mmol/L, p=0.03). In addition, higher cortisol levels were observed in the morning vs evening (128.59±34 vs 67.79±26 ng/mL, p<0.001)., Conclusions: Morning repeated sprint exercise conducted in the postprandial state consistent with the protective effect of higher cortisol levels resulted in a smaller reduction in PG levels compared with evening exercise. This highlights the potential influence of exercise timing on glycemic responses and cortisol secretion in the management of T1D., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to examine the long-term effects of time-restricted eating (TRE), with or without high intensity functional training (HIFT), on body composition and cardiometabolic biomarkers among inactive women with obesity., Methods: Sixty-four women (BMI = 35.03 ± 3.8 kg/m2; age = 32.1 ± 10 years) were randomly allocated to either: (1) TRE (≤8-h daily eating window, with ad libitum energy intake) group; (2) HIFT (3 sessions/week) group; or (3) TRE combined with HIFT (TRE-HIFT) group. The interventions lasted 12 weeks with a pre-post measurement design. A HIFT session consists of 8 sets of multiple functional exercises with self-selected intensity (20 or 30s work/10s rest)., Results: TRE-HIFT showed a greater decrease of waist and hip circumferences and fat mass compared to TRE (p = 0.02, p = 0.02 and p<0.01; respectively) and HIFT (p = 0.012, p = 0.028 and p<0.001; respectively). Weight and BMI decreased in TRE-HIFT compared to HIFT group (p<0.001; for both). Fat-free mass was lower in TRE compared to both HIFT and TRE-HIFT groups (p<0.01 and p<0.001; respectively). Total cholesterol, triglyceride, insulin, and HOMA-IR decreased in TRE-HIFT compared to both TRE (p<0.001, p<0.01, p = 0.015 and p<0.01; respectively) and HIFT (p<0.001, p = 0.02, p<0.01 and p<0.001; respectively) groups. Glucose level decreased in TRE-HIFT compared to HIFT (p<0.01). Systolic blood pressure decreased significantly in both TRE-HIFT and HIFT groups compared to TRE group (p = 0.04 and p = 0.02; respectively)., Conclusion: In inactive women with obesity, combining TRE with HIFT can be a good strategy to induce superior effects on body composition, lipid profile and glucose regulation compared with either diet or exercise intervention alone., Trial Registration: Clinical Trials Number: PACTR202301674821174., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Ameur et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Long-term hyperglycemia in individuals with type 2 diabetes (T2D) can detrimentally impact pulmonary function and muscle oxygenation. As a result, these factors can impede the body's adaptation to physical exertion. We aimed to evaluate the oxygen pathway during maximal exercise among overweight/obese individuals with type 2 diabetes free from complications, in comparison with a group of matched overweight/obese individuals without diabetes, specifically concentrating on the effects on pulmonary function and muscle oxygenation. Fifteen overweight/obese adults with type 2 diabetes [glycated hemoglobin (HbA1c) = 8.3 ± 1.2%] and 15 matched overweight/obese adults without diabetes underwent pre- and post exercise lung function assessment. A maximal incremental exercise test was conducted, monitoring muscle oxygenation using near-infrared spectroscopy and collecting arterial blood gas samples. Both groups exhibited normal lung volumes at rest and after exercise. Spirometric lung function did not significantly differ pre- and post exercise in either group. During maximal exercise, the type 2 diabetes group showed significantly lower augmentation in total hemoglobin and deoxygenated hemoglobin compared with the control group. Despite comparable usual physical activity levels and comparable heart rates at exhaustion, the type 2 diabetes group had a lower peak oxygen consumption than controls. No significant differences were found in arterial blood gas analyses ([Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) between the groups. Individuals with type 2 diabetes free from complications displayed normal pulmonary function at rest and post exercise. However, impaired skeletal muscle oxygenation during exercise, resulting from reduced limb blood volume and altered muscle deoxygenation, may contribute to the lower V̇o 2peak observed in this population. NEW & NOTEWORTHY Individuals with type 2 diabetes free from micro- and macrovascular complications have normal resting pulmonary function, but their V̇o 2peak is impaired due to poor skeletal muscle oxygenation during exercise. Tailoring exercise regimes for this population should prioritize interventions aimed at enhancing muscle oxygenation and blood flow improvement.

Aim: From an early age, exercise is key to managing type 1 diabetes (T1D). However, hypoglycemia around aerobic exercise is a major barrier to physical activity in children. We explore whether intermittent high-intensity aerobic exercise (IHE), designed to mimic spontaneous childhood physical activity patterns, offers better protection against glycemic drop than continuous moderate-intensity exercise (CME)., Methods: Five boys and 7 girls with T1D (9.8 ± 1.4y) performed ergo cycle-based randomized CME and IHE of identical duration and total mechanical load [50 %PWC 170 vs. 15sec(150 %PWC 170 )/30 sec passive recovery; both during two 10-min sets, 5 min in-between]. Capillary glycemia during exercise and interstitial glucose during recovery were compared between exercises and an inactive condition, controlling for baseline glycemia, carbohydrate and insulin., Results: The exercise-induced decrease in capillary glycemia was attenuated by 1.47 mmol·L -1 for IHE vs. CME (P < 0.05). No symptomatic hypoglycemic episodes occurred during exercises. Post-exercise time in hypoglycemia did not differ between conditions. During early recovery, CME reduced time spent > 16.7 mmol·L -1 compared with inactive days (P < 0.05; CME: 0 %; IHE: 16,7 %; INACTIVE: 41,7 %)., Conclusion: IHE appeared to limit the glycemic drop compared to CME. Performing 20-min CME or IHE was not associated with increased hypoglycemic risk compared to being inactive. CME appeared even transiently protective against serious hyperglycemia., 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 © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Monitoring key physiological metrics, including heart rate and heart rate variability, has been shown to be of value in exercise science, disease management, and overall health. The purpose of this study was to investigate the diurnal variation of physiological responses and physical performances using digital biomarkers as a precise measurement tool during a walking football match (WFM) in higher-weight men. Nineteen males (mean age: 42.53 ± 12.18 years; BMI: 33.31 ± 4.31 kg·m -2 ) were engaged in a WFM at two different times of the day. Comprehensive evaluations of physiological parameters (e.g., cardiac autonomic function, lactate, glycemia, and oxygen saturation), along with physical performance, were assessed before, during, and after the match. Overall, there was a significant interaction (time of day x WFM) for mean blood pressure (MBP) ( p = 0.007) and glycemia ( p = 0.039). Glycemia decreased exclusively in the evening after WFM ( p = 0.001), while mean blood pressure did not significantly change. Rating of perceived exertion was significantly higher in the evening than in the morning ( p = 0.04), while the heart rate recovery after 1 min (HRR60s) of the match was lower in the evening than in the morning ( p = 0.048). Overall, walking football practice seems to be safe, whatever the time of day. Furthermore, HRR60, glycemia, and (MBP) values were lower in the evening compared to the morning, suggesting that evening exercise practice could be safer for individuals with higher weight. The utilization of digital biomarkers for monitoring health status during WFM has been shown to be efficient.

This study aimed to investigate whether Chronic Kidney Disease (CKD) influences O 2 supply including O 2 delivery and release to the active muscles during maximal physical exercise. Twelve CKD patients undergoing dialysis therapy (HD group) and twelve healthy adults (CTR group) performed an incremental exercise test to determine maximal oxygen uptake (VO 2peak ). Throughout the exercise, near-infrared spectroscopy allowed the investigation of changes in oxyhemoglobin (∆O 2 Hb), deoxyhemoglobin (∆HHb), and total hemoglobin (∆THb) in the vastus lateralis muscle. VO 2peak was significantly lower in HD group. In addition, HD patients had impaired changes in muscular oxygenation (∆HHb and ∆O 2 Hb) and blood volume (∆THb) during the exercise (p < 0.05). Moreover, a positive correlation was observed between VO 2peak and muscle blood volume (∆THb) in both groups (p < 0.05). This study provides the first evidence that HD patients displayed lower VO 2peak and blunted muscular deoxyhemoglobin increase during exercise. This result supports the hypothesis of an increase in oxygen affinity and/or mitochondrial dysfunction in this population., Competing Interests: Declaration of Competing Interest Authors declare that they have no conflict of interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Aims: Type 1 diabetes is associated with a substantially increased risk of impaired lung function, which may impair aerobic fitness. We therefore aimed to examine the ventilatory response during maximal exercise and the pulmonary diffusion capacity function at rest in individuals with uncomplicated type 1 diabetes., Methods: In all, 17 adults with type 1 diabetes free from micro-macrovascular complications (glycated haemoglobin: 8.0 ± 1.3%), and 17 non-diabetic adults, carefully matched to the type 1 diabetes group according to gender, age, level of physical activity and body composition, participated in our study. Lung function was assessed by spirometry and measurements of the combined diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) at rest. Subjects performed a maximal exercise test during which the respiratory parameters were measured., Results: At rest, DLCO (30.4 ± 6.1 ml min -1  mmHg -1 vs. 31.4 ± 5.7 ml min -1 mmHg -1 , respectively, p = 0.2), its determinants Dm (membrane diffusion capacity) and Vc (pulmonary capillary volume) were comparable among type 1 diabetes and control groups, respectively. Nevertheless, spirometry parameters (forced vital capacity = 4.9 ± 1.0 L vs. 5.5 ± 1.0 L, p < 0.05; forced expiratory volume 1 = 4.0 ± 0.7 L vs. 4.3 ± 0.7 L, p < 0.05) were lower in individuals with type 1 diabetes, although in the predicted normal range. During exercise, ventilatory response to exercise was different between the two groups: tidal volume was lower in type 1 diabetes vs. individuals without diabetes (p < 0.05). Type 1 diabetes showed a reduced VO 2max (34.7 ± 6.8 vs. 37.9 ± 6.3, respectively, p = 0.04) in comparison to healthy subjects., Conclusions: Individuals with uncomplicated type 1 diabetes display normal alveolar-capillary diffusion capacity and at rest, while their forced vital capacity, tidal volumes and VO 2 are reduced during maximal exercise., (© 2022 The Authors. Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.)

Objectives: Our aim in this study was to identify challenges and gaps in Canadian practices in screening, diagnosis, and treatment of cystic fibrosis-related diabetes (CFRD), with the goal of informing a Canadian-specific guideline for CFRD., Methods: We conducted an online survey of health-care professionals (97 physicians and 44 allied health professionals) who care for people living with CF (pwCF) and/or CFRD (pwCFRD)., Results: Most pediatric centres followed <10 pwCFRD and adult centres followed >10 pwCFRD. Children with CFRD are usually followed at a separate diabetes clinic, whereas adults with CFRD may be followed by respirologists, nurse practitioners, or endocrinologists in a CF clinic or in a separate diabetes clinic. Less than 25% of pwCF had access to an endocrinologist with a special interest or expertise in CFRD. Many centres perform screening oral glucose tolerance testing with fasting and 2-hour time points. Respondents, especially those working with adults, also indicate use of additional tests for screening not currently recommended in CFRD guidelines. Pediatric practitioners tend to only use insulin to manage CFRD, whereas adult practitioners are more likely to use repaglinide as an alternative to insulin., Conclusions: Access to specialized CFRD care may be a challenge for pwCFRD in Canada. There appears to be wide heterogeneity of CFRD care organization, screening, and treatment among health-care providers caring for pwCF and/or pwCFRD across Canada. Practitioners working with adult pwCF are less likely to adhere to current clinical practice guidelines than practitioners working with children., (Copyright © 2023 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.)

Background and Aims: We investigated, in men with obesity, the efficacy of the combination of two strategies (Ramadan diurnal intermittent fasting 'RDIF' strategy vs RDIF plus concurrent training program 'RDIF-CT' strategy) known for their positive impact on body composition and then we explored the possible impact on metabolic and inflammatory biomarkers., Methods and Results: Twenty obese men, age: 31.8 ± 7.05 years, BMI: 33.1 ± 4.2 kg m -2 , performing regularly RDIF, were randomized into two groups: RDIF-CT (n = 10) and RDIF without training (RDIF-NCT) (n = 10). The RDIF-CT group participated in High intensity interval training (HIIT) program combined with resistance exercises for 4 weeks. Body composition, blood glucose, lipid profile, liver biomarkers and inflammation were assessed before and after 4-week RDIF. Both groups showed a significant decrease in weight, fat mass (FM), fat percentage (Fat%) and waist circumference (WC) and an improvement in blood glucose, lipid profile and inflammation. Fat free mass decreased significantly in RDIF-NCT (p < 0.05) while remaining unchanged in RDIF-CT. However, RDIF-CT induced greater improvements in body composition (i.e., weight, FM, Fat% and WC (p < 0.05, p < 0.01, p < 0.01 and p < 0.05; respectively)) as well as greater decrease in lipid biomarkers (i.e., TC, TG and LDL (p < 0.01 for all)), inflammation (i.e., CRP (p < 0.05)), and liver damage (i.e., ASAT, ALAT and Gamma-GT (p < 0.01, p < 0.05 and p < 0.001; respectively)) compared to RDIF-NCT group pre-post intervention., Conclusions: Our results suggest that a combination of RDIF and CT induces greater changes in body composition, lipid profile, inflammation and liver biomarkers compared to RDIF strategy alone., Clinical Trial Register: PACTR202203475387226., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2022. Published by Elsevier B.V.)

Objectives: Ever since the first research on barriers to physical activity (PA) highlighting fear of hypoglycemia as a major barrier, many studies have attempted to understand their demographic and behavioural determinants. However, no research has been conducted on whether these perceived barriers toward PA are based on real-life-experienced adverse glycemic effects of exercise., Methods: Sixty-two adults and 53 children/adolescents living with type 1 diabetes, along with their parents, completed the Barriers to Physical Activity in Type 1 Diabetes-1 (BAPAD-1) questionnaire on barriers to PA. Continuous glucose-monitoring data were collected during 1 week of everyday life for 26 adults and 33 children/adolescents. Multiple linear regressions were used to explore links between BAPAD-1 scores and glycemic excursions experienced during and after everyday-life self-reported PA sessions, controlling for behavioural (accelerometry) and demographic confounders., Results: In children/adolescents, the more time spent in hypoglycemia on nights after PA sessions, the more they reported hypoglycemic risk as a barrier (ß=+0.365, p=0.034). Conversely, in adults, the higher the proportion of PA sessions accompanied by a drop in blood glucose, the less hypoglycemia was a barrier (ß=-0.046, p=0.004). In parents, BAPAD-1 scores were unrelated to children/adolescents' everyday-life exercise-induced hypo/hyperglycemia., Conclusions: In children/adolescents, fear of hypoglycemia was predominant in those exposed to nocturnal hypoglycemia associated with PA sessions. In adults, fewer barriers may mean they accept a bigger drop in their glycemia during PA. This shows the importance of finding and promoting age-specific solutions to prevent exercise-induced hypoglycemia., (Copyright © 2022 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.)

Aims: To assess the safety and efficacy of two exercise sessions performed 60- and 120-min postmeal with a combination of meal bolus reduction and increased glucose target to the automated insulin delivery (AID) system. Methods: A randomized crossover trial in 13 adult participants (6 females) living with type 1 diabetes using AID (A1c = 7.9% ± 0.6%, age = 53.5 ± 15.5 years, T1D duration = 29.0 ± 16.0 years) was conducted. Just before breakfast, at the time of meal bolus, the AID glucose target was increased from 6 to 9 mmol/L, and a meal bolus reduction of 33% was applied. Two 60-min exercise sessions (60% of VO 2 peak) were undertaken either 60 min (60EX) or 120 min (120EX) after a standardized breakfast, followed by a 90-min recovery period. Results: The mean reduction in plasma glucose (PG) levels from prebreakfast to postexercise (-0.8 ± 2.4 mmol/L vs. +0.3 ± 2.3 mmol/L, P  = 0.082) were similar between 60EX and 120EX. From prebreakfast to postexercise, PG times in range (3.9-10.0 mmol/L; 63.4% ± 43.1% 60EX vs. 51.9% ± 29.7% 120EX, P  = 0.219) and time above range (>10.0 mmol/L; 36.3% ± 43.3% 60EX vs. 48.1% ± 29.7% 120EX, P  = 0.211) did not differ between interventions. The 60EX attenuated the glucose rise between premeal to pre-exercise (+1.8 ± 2.1 mmol/L 60EX vs. +3.9 ± 2.1 mmol/L 120EX, P  = 0.001). No hypoglycemic events (<3.9 mmol/L) occurred during the study. Conclusion: Premeal announcement combining meal bolus reduction and increased glucose target was effective and safe during 60 min of moderate-intensity aerobic exercise, whether exercise onset was 60 or 120 min following a meal. Clinical Trial Registration No.: NCT04031599.

Objective: Studies investigating strategies to limit the risk of nocturnal hypoglycemia associated with physical activity (PA) are scarce and have been conducted in standardized, controlled conditions in people with type 1 diabetes (T1D). This study sought to investigate the effect of daily PA level on nocturnal glucose management in free-living conditions while taking into consideration reported mitigation strategies to limit the risk of nocturnal hyoglycemia in people with T1D., Methods: Data from 25 adults (10 males, 15 females, HbA 1c : 7.6 ± 0.8%), 20-60 years old, living with T1D, were collected. One week of continuous glucose monitoring and PA (assessed using an accelerometer) were collected in free-living conditions. Nocturnal glucose values (midnight-6:00 am) following an active day "ACT" and a less active day "L-ACT" were analyzed to assess the time spent within the different glycemic target zones (<3.9 mmol/L; 3.9 - 10.0 mmol/L and >10.0 mmol/L) between conditions. Self-reported data about mitigation strategies applied to reduce the risk of nocturnal hypoglycemia was also analyzed., Results: Only 44% of participants reported applying a carbohydrate- or insulin-based strategy to limit the risk of nocturnal hypoglycemia on ACT day. Nocturnal hypoglycemia occurrences were comparable on ACT night versus on L-ACT night. Additional post-meal carbohydrate intake was higher on evenings following ACT (27.7 ± 15.6 g, ACT vs. 19.5 ± 11.0 g, L-ACT; P=0.045), but was frequently associated with an insulin bolus (70% of participants). Nocturnal hypoglycemia the night following ACT occurred mostly in people who administrated an additional insulin bolus before midnight (3 out of 5 participants with nocturnal hypoglycemia)., Conclusions: Although people with T1D seem to be aware of the increased risk of nocturnal hypoglycemia associated with PA, the risk associated with additional insulin boluses may not be as clear. Most participants did not report using compensation strategies to reduce the risk of PA related late-onset hypoglycemia which may be because they did not consider habitual PA as something requiring treatment adjustments., Competing Interests: Research grants: Diabetes Canada, Astra-Zeneca, E Lilly, Cystic Fibrosis Canada, CIHR, FFRD, Janssen, JDRF, Merck, NIH, Novo-Nordisk, Société Francophonedu Diabète, Sanofi-Aventis, Vertex Pharmaceutical. Consulting /advisory panel: Abbott, Astra-Zeneca, Bayer, Boehringer I, Dexcom, E Lilly, HLS therapeutics, INESSS, Insulet, Janssen, Medtronic, Merck, Novo-Nordisk, Pfizer, Sanofi-Aventis. Honoraria for conferences: Abbott, Astra-Zeneca, Boehringer I, CPD Network, Dexcom, CMS Canadian Medical&Surgical Knowledge Translation Research group, E Lilly, Janssen, Medtronic, Merck, Novo-Nordisk, Sanofi-Aventis, Tandem, Vertex Pharmaceutical. Consumable gift (in Kind): E Lilly, Medtronic Unrestricted grants for clinical and educational activities: Abbott, E Lilly, Medtronic, Merck, Novo Nordisk, Sanofi-Aventis Patent: T2D risk biomarkers, catheter life Purchase fees: E Lilly (artificial pancreas)., (Copyright © 2022 Molveau, Rabasa-Lhoret, Myette-Côté, Messier, Suppère, J. Potter, Heyman and Tagougui.)

Objective: We investigated the effect of two key timings for basal insulin rate reduction on exercise-induced glucose changes and explored the association between circulating insulin concentrations and muscle vasoreactivity. Research Design and Methods: Twenty adults and adolescents performed 60-min exercise sessions (ergocycle) at 60% VO 2peak , 240 min after a standardized lunch. In a randomized order, we compared an 80% basal insulin reduction applied 40 min (T-40) or 90 min (T-90) before exercise onset. Near-infrared spectroscopy was used to investigate muscle hemodynamics at vastus lateralis. Glucose and insulin plasma concentrations were measured. Results: Reduction in plasma glucose (PG) level during exercise was attenuated during T-90 versus T-40 strategy (-0.89 ± 1.89 mmol/L vs. -2.17 ± 2.49 mmol/L, respectively; P  = 0.09). Linear mixed model analysis showed that PG dropped by an additional 0.01 mM per minute in T-40 versus T-90 (time × strategy interaction, P  < 0.05). The absolute number of hypoglycemic events was not different between the two strategies, but they occurred later with T-90. Free insulin tends to decrease more during the pre-exercise period in the T-90 strategy ( P  = 0.08). Although local muscle vasodilatation (ΔTHb) was comparable between the two strategies, we found that PG dropped more in cases of higher exercise-induced skeletal muscle vasodilatation (ΔTHb × time interaction P  < 0.005, e : -0.0086 mM/min and additional mM of ΔTHb). Conclusion: T-90 timing reduced exercise-induced drop in PG and delayed the occurrence of hypoglycemic episodes compared with T-40 timing without a significant reduction in the number of events requiring treatment. Trial registration: ClinicalTrials.gov identifier: NCT03349489.

Physical activity (PA) is important for individuals living with type 1 diabetes (T1D) due to its various health benefits. Nonetheless, maintaining adequate glycemic control around PA remains a challenge for many individuals living with T1D because of the difficulty in properly managing circulating insulin levels around PA. Although the most common problem is increased incidence of hypoglycemia during and after most types of PA, hyperglycemia can also occur. Accordingly, a large proportion of people living with T1D are sedentary partly due to the fear of PA-associated hypoglycemia. Continuous subcutaneous insulin infusion (CSII) offers a higher precision and flexibility to adjust insulin basal rates and boluses according to the individual's specific needs around PA practice. Indeed, for physically active patients with T1D, CSII can be a preferred option to facilitate glucose regulation. To our knowledge, there are no guidelines to manage exercise-induced hypoglycemia during PA, specifically for individuals living with T1D and using CSII. In this review, we highlight the current state of knowledge on exercise-related glucose variations, especially hypoglycemic risk and its underlying physiology. We also detail the current recommendations for insulin modulations according to the different PA modalities (type, intensity, duration, frequency) in individuals living with T1D using CSII., (Copyright © 2021. Published by Elsevier Inc.)

Background and Aims: During aerobic physical activity (PA), hypoglycemia is common in people with type 1 diabetes (T1D). Few studies have compared the effectiveness of different carbohydrate (CHO) intake strategies to prevent PA-induced hypoglycemia. Our objective was to compare the efficacy of two CHO intake strategies, same total amount but different CHO intake timing, to maintain glucose levels in the target range (4.0-10.0 mmol/L) during PA in people with T1D., Methods and Results: An open-label, randomized, crossover study in 33 participants (21 adults; 12 adolescents). Participants practiced 60 min PA sessions (ergocyle) at 60% VO 2peak 3.5 h after lunch comparing an intake of 0.5 g of CHO per kg of body weight applied in a pre-PA single CHO intake (SCI) or in a distributed CHO intake (DCI) before and during PA. The percentage of time spent in glucose level target range during PA was not different between the two strategies (SCI: 75 ± 35%; DCI: 87 ± 26%; P = 0.12). Hypoglycemia (<4.0 mmol/L) occurred in 4 participants (12%) with SCI compared to 6 participants (18%) with DCI (P = 0.42). The SCI strategy led to a higher increase (P = 0.01) and variability of glucose levels (P = 0.04) compared with DCI., Conclusions: In people living with T1D, for a 60 min moderate aerobic PA in the post-absorptive condition, a 0.5 g/kg CHO intake helped most participants maintain acceptable glycemic control with both strategies. No clinically significant difference was observed between the SCI and DCI strategies. ClinicalTrials.gov Identifier: NCT03214107 (July 11, 2017)., Competing Interests: Declaration of competing interest R.R.-L.: Research grants: Diabetes Canada, Astra-Zeneca, E Lilly, Cystic Fibrosis Canada, CIHR, Janssen, JDRF, Merck, NIH, Novo-Nordisk, Prometic Société Francophone du Diabète, Sanofi-Aventis, Vertex Pharmaceutical. Consulting/advisory panel: Abbott, Amgen, Astra-Zeneca, Boehringer I, Dexcom, E Lilly, HSL therapeutics, Insulet, Janssen, Medtronic, Merck, Neomed, Novo-Nordisk, Roche, Sanofi-Aventis. Honoraria for conferences: Abbott, Astra-Zeneca, Boehringer I, CPD Network, Dexcom, E Lilly, Janssen, Medtronic, Merck, Novo-Nordisk, Sanofi-Aventis, Vertex Pharmaceutical. Consumable gift (in Kind): Animas, E Lilly, Medtronic. Unrestricted grants fors clinical and educational activities: Abbott, E Lilly, Medtronic, Merck, Novo Nordisk, Sanofi-Aventis. Patent: T2D risk biomarkers, catheter life. Purchase fees: E Lilly (artificial pancreas). M.H.: holds a Diabetes Junior Investigator Award from the Canadian Society of Endocrinology and Metabolism/AstraZeneca and a Fonds de Recherche du Québec - Santé Junior 2 salary award. L.L.: Lilly and Dexcom advisory committee, research funds (paid to the institution): Merck, and Astra-Zeneca. Intellectual property in the field of closed loop (not marketed). V.M.: Purchase fees: E Lilly (artificial pancreas). L.G.-G: grants from IRSC, grants from FRQS, during the conduct of the study. M.-B.S: Grants from JDRF/ISPAD Research Fellowship, during the conduct of the study. C.S., A.F., N.T., S.T. & A.S. have no relevant conflict of interest to disclose., (Copyright © 2020 The Italian Diabetes Society, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.)

Background and Aims: There is debate over the independent and combined effects of caloric restriction (CR) and physical activity (PA) on reduction in fat mass and in epicardial fat thickness. We compared the impact of a similar energy deficit prescription by CR or by CR combined with PA on total fat mass, epicardial fat thickness, and cardiometabolic profile in individuals with type 2 diabetes., Methods and Results: In this 16-week randomized controlled study, 73 individuals were randomly enrolled to receive: 1) a monthly motivational phone call (Control), 2) a caloric deficit of -700 kilocalories/day (CR), or 3) a caloric deficit of -500 kilocalories/day combined with a PA program of -200 kilocalories/day (CR&PA). Total fat mass, epicardial fat, and cardiometabolic profile were measured at baseline and after 16 weeks. While comparable weight loss occurred in both intervention groups (-3.9 ± 3.5 kg [CR], -5.1 ± 4.7 kg [CR&PA], -0.2 ± 2.9 kg [Control]), changes in total fat mass were significantly different between all groups (-2.4 ± 2.9 kg [CR], -4.5 ± 3.4 kg [CR&PA], +0.1 ± 2.1 kg [Control]; p < 0.05) as well as epicardial fat thickness (-0.4 ± 1.6 mm [CR], -1.4 ± 1.4 mm [CR&PA], +1.1 ± 1.3 mm [Control]; p < 0.05). There were no significant differences in trends for cardiometabolic parameters improvement between groups., Conclusions: For a similar energy deficit prescription and comparable weight loss, the combination of CR&PA provides a greater reduction in fat mass and epicardial fat thickness than CR alone in individuals with comparable weight loss and with a similar energy deficit prescription. These results, however, do not translate into significant improvements in cardiometabolic profiles. CLINICALTRIALS., Gov Identifier: NCT01186952., Competing Interests: Declaration of competing interest The authors declare that they have no competing interest. Funding was supported by the J.-A. DeSève chair for diabetes research awarded to RRL., (Copyright © 2020 The Italian Diabetes Society, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.)

Aims/hypothesis: Early compromised endothelial function challenges the ability of individuals with type 1 diabetes to perform normal physical exercise. The exact mechanisms underlying this vascular limitation remain unknown, but may involve either formation or metabolism of nitric oxide (NO), a major vasodilator, whose activity is known to be compromised by oxidative stress., Methods: Muscle microvascular reactivity (near-infrared spectroscopy) to an incremental exhaustive bout of exercise was assessed in 22 adults with uncomplicated type 1 diabetes (HbA 1c 64.5 ± 15.7 mmol/mol; 8.0 ± 1.4%) and in 21 healthy individuals (18-40 years of age). NO-related substrates/metabolites were also measured in the blood along with other vasoactive compounds and oxidative stress markers; measurements were taken at rest, at peak exercise and after 15 min of recovery. Demographic characteristics, body composition, smoking status and diet were comparable in both groups., Results: Maximal oxygen uptake was impaired in individuals with type 1 diabetes compared with in healthy participants (35.6 ± 7.7 vs 39.6 ± 6.8 ml min -1  kg -1 , p < 0.01) despite comparable levels of habitual physical activity (moderate to vigorous physical activity by accelerometery, 234.9 ± 160.0 vs 280.1 ± 114.9 min/week). Compared with non-diabetic participants, individuals with type 1 diabetes also displayed a blunted exercise-induced vasoreactivity (muscle blood volume at peak exercise as reflected by ∆ total haemoglobin, 2.03 ± 5.82 vs 5.33 ± 5.54 μmol/l; interaction 'exercise' × 'group', p < 0.05); this was accompanied by lower K + concentration (p < 0.05), reduced plasma L-arginine (p < 0.05)-in particular when HbA 1c was high (mean estimation: -4.0, p < 0.05)-and lower plasma urate levels (p < 0.01). Nonetheless, exhaustive exercise did not worsen lipid peroxidation or other oxidative stress biomarkers, and erythrocytic enzymatic antioxidant resources were mobilised to a comparable extent in both groups. Nitrite and total nitrosation products, which are potential alternative NO sources, were similarly unaltered. Graphical abstract CONCLUSIONS/INTERPRETATION: Participants with uncomplicated type 1 diabetes displayed reduced availability of L-arginine, the essential substrate for enzymatic nitric oxide synthesis, as well as lower levels of the major plasma antioxidant, urate. Lower urate levels may reflect a defect in the activity of xanthine oxidase, an enzyme capable of producing NO from nitrite under hypoxic conditions. Thus, both canonical and non-canonical NO production may be reduced. However, neither of these changes exacerbated exercise-induced oxidative stress., Trial Registration: clinicaltrials.gov NCT02051504.

Aims/hypothesis: For individuals living with type 1 diabetes, closed-loop insulin delivery improves glycaemic control. Nonetheless, maintenance of glycaemic control during exercise while a prandial insulin bolus remains active is a challenge even to closed-loop systems. We investigated the effect of exercise announcement on the efficacy of a closed-loop system, to reduce hypoglycaemia during postprandial exercise., Methods: A single-blind randomised, crossover open-label trial was carried out to compare three strategies applied to a closed-loop system at mealtime in preparation for exercise taken 90 min after eating at a research testing centre: (1) announced exercise to the closed-loop system (increases target glucose levels) in addition to a 33% reduction in meal bolus (A-RB); (2) announced exercise to the closed-loop system and a full meal bolus (A-FB); (3) unannounced exercise and a full meal bolus (U-FB). Participants performed 60 min of exercise at 60% [Formula: see text] 90 min after eating breakfast. The investigators were not blinded to the interventions. However, the participants were blinded to the sensor glucose readings and to the insulin infusion rates throughout the intervention visits., Results: The trial was completed by 37 adults with type 1 diabetes, all using insulin pumps: mean±SD, 40.0 ± 15.0 years of age, HbA 1c 57.1 ± 10.8 mmol/mol (7.3 ± 1.0%). Reported results were based on plasma glucose values. During exercise and the following 1 h recovery period, time spent in hypoglycaemia (<3.9 mmol/l; primary outcome) was reduced with A-RB (mean ± SD; 2.0 ± 6.2%) and A-FB (7.0 ± 12.6%) vs U-FB (13.0 ± 19.0%; p < 0.0001 and p = 0.005, respectively). During exercise, A-RB had the least drop in plasma glucose levels: A-RB -0.3 ± 2.8 mmol/l, A-FB -2.6 ± 2.9 mmol/l vs U-FB -2.4 ± 2.7 mmol/l (p < 0.0001 and p = 0.5, respectively). Comparison of A-RB vs U-FB revealed a decrease in the time spent in target (3.9-10 mmol/l) by 12.7% (p = 0.05) and an increase in the time spent in hyperglycaemia (>10 mmol/l) by 21% (p = 0.001). No side effects were reported during the applied strategies., Conclusions/interpretation: Combining postprandial exercise announcement, which increases closed-loop system glucose target levels, with a 33% meal bolus reduction significantly reduced time spent in hypoglycaemia compared with the other two strategies, yet at the expense of more time spent in hyperglycaemia., Trial Registration: ClinicalTrials.gov NCT0285530 FUNDING: JDRF (2-SRA-2016-210-A-N), the Canadian Institutes of Health Research (354024) and the Fondation J.-A. DeSève chair held by RR-L.

Objective: Long before clinical complications of type 1 diabetes (T1D) develop, oxygen supply and use can be altered during activities of daily life. We examined in patients with uncomplicated T1D all steps of the oxygen pathway, from the lungs to the mitochondria, using an integrative ex vivo (muscle biopsies) and in vivo (during exercise) approach., Research Design and Methods: We compared 16 adults with T1D with 16 strictly matched healthy control subjects. We assessed lung diffusion capacity for carbon monoxide and nitric oxide, exercise-induced changes in arterial O 2 content (SaO 2 , PaO 2 , hemoglobin), muscle blood volume, and O 2 extraction (via near-infrared spectroscopy). We analyzed blood samples for metabolic and hormonal vasoactive moieties and factors that are able to shift the O 2 -hemoglobin dissociation curve. Mitochondrial oxidative capacities were assessed in permeabilized vastus lateralis muscle fibers., Results: Lung diffusion capacity and arterial O 2 transport were normal in patients with T1D. However, those patients displayed blunted exercise-induced increases in muscle blood volume, despite higher serum insulin, and in O 2 extraction, despite higher erythrocyte 2,3-diphosphoglycerate. Although complex I- and complex II-supported mitochondrial respirations were unaltered, complex IV capacity (relative to complex I capacity) was impaired in patients with T1D, and this was even more apparent in those with long-standing diabetes and high HbA 1c . [Formula: see text]O 2max was lower in patients with T1D than in the control subjects., Conclusions: Early defects in microvascular delivery of blood to skeletal muscle and in complex IV capacity in the mitochondrial respiratory chain may negatively impact aerobic fitness. These findings are clinically relevant considering the main role of skeletal muscle oxidation in whole-body glucose disposal., (© 2019 by the American Diabetes Association.)

Physical activity is important for patients living with type 1 diabetes (T1D) but limited by the challenges associated with physical activity induced glucose variability. Optimizing glycemic control without increasing the risk of hypoglycemia is still a hurdle despite many advances in insulin formulations, delivery methods, and continuous glucose monitoring systems. In this respect, the artificial pancreas (AP) system is a promising therapeutic option for a safer practice of physical activity in the context of T1D. It is important that healthcare professionals as well as patients acquire the necessary knowledge about how the AP system works, its limits, and how glucose control is regulated during physical activity. This review aims to examine the current state of knowledge on exercise-related glucose variations especially hypoglycemic risk in T1D and to discuss their effects on the use and development of AP systems. Though effective and highly promising, these systems warrant further research for an optimized use around exercise.

IN BRIEF Artificial pancreas systems are rapidly developing and constitute the most promising technology for insulin-requiring diabetes management. Single-hormone systems (SH-AP) that deliver only insulin and have a hybrid design that necessitates patients' interventions around meals and exercise are the first to appear on the market. Trials with SH-AP have demonstrated improvement in time spent with blood glucose levels within target ranges, with a concomitant decrease in hypoglycemia. Longer and larger trials involving different patient populations are ongoing to further advance this important technology.

Continuous glucose monitoring (CGM) systems help diabetes management in patients with type 1 diabetes (T1D) but could have lower accuracy during exercise. We aim to evaluate the dynamics of CGM accuracy during exercise in patients with T1D. Secondary analysis of data was carried out on 22 patients with T1D (glycated hemoglobin [HbA 1c ]: 7.3% ± 1.0%, diabetes duration: 23 ± 13 years), who did three exercise sessions (45 min at 60% VO 2max on an ergocycle, 3 h postmeal) with paired Dexcom G4 Platinum, and capillary glucose values that were collected every 5 min. Dexcom accuracy was evaluated using sensor bias (SB) and absolute relative difference (ARD). For dynamics of SB analysis, data pairs following hypoglycemia correction were excluded. The analyzed data included 792 pairs (594 during 66 exercise sessions, 198 at rest before exercise). Median ARD was 8.44 (5.35-12.13)% at rest and increased to 16.77 (10.75-26.72)% during exercise ( P < 0.001). During exercise, mean SB values evolved from T0 minutes = 5.95 ± 16.04 mg/dL (exercise start); T5 = 9.55 ± 16.40; T10 = 13.51 ± 18.02; T15 = 15.32 ± 20.36; T20 = 17.30 ± 18.92; T25 = 19.46 ± 17.48; T30 = 21.08 ± 19.64; T35 = 19.10 ± 20.36; T40 = 19.82 ± 20.18; and T45 = 18.02 ± 20.90 (exercise end). CGM overestimated capillary at a mean SB of 14.23 ± 16.76 mg/dL over the whole exercise session. CGM accuracy decreased during moderate aerobic exercise as previously described. However, the trend to overestimate capillary glucose was maintained at relatively stable values within 15 min of exercise initiation, which could help patients in their clinical decisions. Similar analyses would be needed for other types of exercise.

Physical activity is highly recommended for patients living with type 1 diabetes (T1D) due to its varied health benefits. Nevertheless, glucose management, during and in the hours following exercise, represents a great challenge for these patients who most often end up leading a sedentary life style. Important technological advances in insulin delivery devices and glucose monitoring are now available and continue to progress. These technologies could be used to alleviate glucose management related to physical activity in T1D. Continuous glucose monitoring (CGM) helps patients observe the trends of glycemic fluctuations when exercising and in the following night to deal pre-emptively with hypoglycemic risks and treat hypoglycemic episodes in a timely manner. Insulin pumps offer the flexibility of adjusting insulin basal rates and boluses according to patient's specific needs around exercise. The artificial pancreas links CGM to pump through an intelligent hormone dosing algorithm to close the loop of glucose control and has thus the potential to ease the burden of exercise in T1D. This review will examine and discuss the literature related to physical activity practice using each of these technologies. The aim is to discuss their benefits as well as their limitations and finally the additional research needed in the future to optimize their use in T1D.