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Hybrid closed-loop (HCL) systems remain underexplored within aviation, and as atmospheric pressure changes can independently affect insulin pumps and continuous glucose monitoring readings, this preliminary study assessed the feasibility of HCL safety evaluation, in both fasting and post-prandial states, by using hypobaric chamber to simulate flights. Participants with type 1 diabetes and on HCL were studied: Medtronic Guardian 4-Medtronic 780G-SmartGuard (n = 4), Dexcom G6-Omnipod DASH-Android APS (n = 1), and Dexcom G6-Ypsomed Pump-CamAPS (n = 1). Flight cabin pressures of 550 mmHg and 750 mmHg were simulated in a hypobaric chamber. Seven-hundred-50 glucose measurements were taken, with glucose levels demonstrating a stable decline to 4 mmol/L during fasting. To maintain a tight fasting and post-prandial glucose range across the different pressure settings, the HCL administered insulin as expected. While not demonstrating any apparent issues, repeating flight simulation protocol with other systems, examining longer flights, and undertaking larger, powered randomised controlled trials can confirm their safety in aviation. [ABSTRACT FROM AUTHOR]

Black African-Caribbean (BAC) populations are at greater risk of cardiometabolic disease than White Europeans (WE), despite exhibiting lower fasting triacylglycerol (TAG) concentrations. However, limited data exist regarding postprandial fatty acid metabolism in BAC populations. This study determined the ethnic differences in postprandial fatty acid metabolism between overweight and obese WE and BAC men. WE [n = 10, age 33.3 ± 1.7 yr; body mass index (BMI) = 26.8 (25.8–31.0) kg/m2] and BAC [n = 9, age 27.9 ± 1.0 yr; BMI = 27.5 (26.0–28.6) kg/m2] men consumed two consecutive (at 0 and 300 min) moderate-to-high-fat meals—the first labeled with [U-13C]palmitate. The plasma concentration and appearance of meal-derived fatty acids in very-low-density lipoprotein (VLDL)-TAG, chylomicron-TAG, and nonesterified fatty acid (NEFA) were determined over an 8-h postprandial period. Indirect calorimetry with 13CO2 enrichment determined total and meal-derived fatty acid oxidation rates, and plasma β-hydroxybutyrate (3-OHB) concentration was measured to assess ketogenesis. BAC exhibited lower postprandial TAG [area under the curve (AUC0–480) = 671 (563–802) vs. 469 (354–623) mmol/L/min, P = 0.022] and VLDL-TAG [AUC0–480 = 288 ± 30 vs. 145 ± 27 mmol/L/min, P = 0.003] concentrations than WE. The appearance of meal-derived fatty acids in VLDL-TAG was lower in BAC than in WE (AUC0–480 = 133 ± 12 vs. 78 ± 13 mmol/L/min, P = 0.007). Following the second meal, BAC showed a trend for lower chylomicron-TAG concentration [AUC300–480 = 69 (51–93) vs. 43 (28–67) mmol/L/min, P = 0.057]. There were no ethnic differences in the appearance of chylomicron-TAG, cumulative fatty acid oxidation, and the NEFA:3-OHB ratio (P > 0.05). In conclusion, BAC exhibit lower postprandial TAG concentrations compared with WE men, driven by lower VLDL-TAG concentrations and possibly lower chylomicron-TAG in the late postprandial period. These findings suggest that postprandial fatty acid trafficking may be a less important determinant of cardiometabolic risk in BAC than in WE men. NEW & NOTEWORTHY: Postprandial TAG is lower in Black African-Caribbean men than in White European men, and this is likely driven by lower meal-derived VLDL-TAG in Black African-Caribbean men. This observation could suggest that fatty acid trafficking may be a less important determinant of cardiometabolic risk in Black Africans than in White European men. [ABSTRACT FROM AUTHOR]

Objective: This work aimed to investigate the effect of the SGLT2 inhibitor, dapagliflozin (DAPA), on cardiac function and the metabolic and hormonal response to moderate exercise in people with type 2 diabetes. Methods: This was a double-blind, placebo-controlled crossover study with a 4-week washout period. Nine participants were randomly assigned to receive either 4 weeks of DAPA or 4 weeks of placebo. After each treatment, they underwent an exercise protocol with 2 consecutive 10- minute stages at a constant load corresponding to 40% and 70% maximal oxygen consumption (VO2max), coupled with hormonal and metabolic analysis. A blinded transthoracic echocardiogram was performed 3 days later. Results: During the exercise protocol, glucose and lactate were lower (P<.0001 and P<.05, respectively) and β-hydroxybutyrate (BOBH) and growth hormone (GH) were higher (P<.0005 and P= .01) following DAPA treatment compared to placebo. There was a trend for lower insulin with DAPA. Adrenalin, noradrenalin, and glucagon were not different. Following DAPA participants demonstrated an increased mean peak diastolic mitral annular velocity (e') in comparison to placebo (P=.03). The indexed left atrial volume and right ventricular e" were reduced following DAPA compared with placebo (P=.045 and P=.042, respectively). Arterial stiffness was not different between treatments (DAPA 9.35±0.60 m/s; placebo 9.07±0.72 m/s). Conclusion: During exercise, GH may be more important than catecholamines in driving the shift from glucose to fatty acid metabolism by SGLT2 inhibitors. The 4-week crossover design showed changes in cardiac function were rapid in onset and reversible. [ABSTRACT FROM AUTHOR]

We have separated the effect of insulin on glucose distribution/transport, glucose disposal, and endogenous production (EGP) during an intravenous glucose tolerance test (IVGTT) by use of a dual-tracer dilution methodology. Six healthy lean male subjects (age 33 [+ or -] 3 yr, body mass index 22.7 [+ or -] 0.6 kg/[m.sup.2]) underwent a 4-h IVGTT (0.3 g/kg glucose enriched with 3-6% D-[[U-.sup.13]C]glucose and 5-10% 3-O-methyl-D-glucose) preceded by a 2-h investigation under basal conditions (5 mg/kg of D-[[U.sup.-13]C]glucose and 8 mg/kg of 3-O-methyl-D-glucose). A new model described the kinetics of the two glucose tracers and native glucose with the use of a two-compartment structure for glucose and a one-compartment structure for insulin effects. Insulin sensitivities of distribution/transport, disposal, and EGP were similar (11.5 [+ or -] 3.8 vs. 10.4 [+ or -] 3.9 vs. 11.1 [+ or -] 2.7 x [10.sup.-2] ml * [kg.sup.-1] * [min.sup.-1] per mU/l; P = nonsignificant, ANOVA). When expressed in terms of ability to lower glucose concentration, stimulation of disposal and stimulation of distribution/transport accounted each independently for 25 and 30%, respectively, of the overall effect. Suppression of EGP was more effective (P < 0.01, ANOVA) and accounted for 50% of the overall effect. EGP was suppressed by 70% (52-82%) (95% confidence interval relative to basal) within 60 min of the IVGTT; glucose distribution/ transport was least responsive to insulin and was maximally activated by 62% (34-96%) above basal at 80 min compared with maximum 279% (116-565%) activation of glucose disposal at 20 min. The deactivation of glucose distribution/transport was slower than that of glucose disposal and EGP (P < 0.02) with half-times of 207 (84-510), 12 (7-22), and 29 (16-54) min, respectively. The minimal-model insulin sensitivity was tightly correlated with and linearly related to sensitivity of EGP (r = 0.96, P < 0.005) and correlated positively but nonsignificantly with distribution/transport sensitivity (r = 0.73, P = 0.10) and disposal sensitivity (r = 0.55, P = 0.26). We conclude that, in healthy subjects during an IVGTT, the two peripheral insulin effects account jointly for approximately one-half of the overall insulin-stimulated glucose lowering, each effect contributing equally. Suppression of EGP matches the effect in the periphery. glucose kinetics; compartment modeling; D-[[U.sup.-13]C]glucose; 3-O-methyl-D-glucose; insulin action; glucose transport; glucose disposal; endogenous glucose production; intravenous glucose tolerance test