Automated Insulin Delivery Around Exercise in Adults with Type 1 Diabetes: A Pilot Randomized Controlled Study.

Aim: To assess the effectiveness of an automated insulin delivery (AID) system around exercise in adults with type 1 diabetes (T1D). Methods: This was a three-period, randomized, crossover trial involving 10 adults with T1D (hemoglobin A1C; HbA1c: 8.3% ± 0.6% [67 ± 6 mmol/mol]) using an AID system (MiniMed 780G; Medtronic USA). Participants performed 45 min of moderate intensity continuous exercise 90 min after consuming a carbohydrate-based meal using three strategies: (1) a 100% dose of bolus insulin with exercise announcement immediately at exercise onset "spontaneous exercise" (SE) or a 25% reduced dose of bolus insulin with exercise announcement either (2) 90 min (AE90) or (3) 45 min (AE45) before exercise. Venous-derived plasma glucose (PG) taken in 5 and 15 min intervals over a 3 h collection period was stratified into the percentage of time spent below (TBR [<3.9 mmol/L]), time in range (TIR [3.9-10 mmol/L]), and time above range (TAR [ > 10 mmol/L]). In instances of hypoglycemia, PG data were carried forward for the remainder of the visit. Results: Overall, TBR was greatest during SE (SE: 22.9 ± 22.2, AE90: 1.1 ± 1.9, AE45: 7.8% ± 10.3%, P = 0.029). Hypoglycemia during exercise occurred in four participants in SE but one in both AE90 and AE45 (ꭓ2 [2] = 3.600, P = 0.165). In the 1 h postexercise period, AE90 was associated with higher TIR (SE: 43.8 ± 49.6, AE90: 97.9 ± 5.9, AE45: 66.7% ± 34.5%, P = 0.033), lower TBR (SE: 56.3 ± 49.6, AE90: 2.1 ± 5.9, AE45: 29.2% ± 36.5%, P = 0.041) with the greatest source of discrepancy observed relative to SE. Conclusion: In adults using an AID system and undertaking postprandial exercise, a strategy involving both bolus insulin dose reduction and exercise announcement 90 min before commencing the activity may be most effective in minimizing dysglycemia. The study was registered as a clinical trial (Clinical Trials Register; NCT05134025).

Glycemia Around Exercise in Adults with Type 1 Diabetes Using Automated and Nonautomated Insulin Delivery Pumps: A Switch Pilot Trial.

In an in-patient switch study, 10 adults with type 1 diabetes (T1D) performed 45 min of moderate-intensity exercise on 2 occasions: (1) when using their usual insulin pump (UP) and (2) after transitioning to automated insulin delivery (AID) treatment (MiniMed™ 780G). Consensus glucose management guidelines for performing exercise were applied. Plasma glucose concentrations measured over a 3-h monitoring period were stratified into time below range (TBR, <3.9 mmol/L), time in range (TIR, 3.9-10.0 mmol/L), and time above range (TAR, >10.0 mmol/L). Overall, TBR (UP: 11 ± 21 vs. AID: 3% ± 10%, P = 0.413), TIR (UP: 53 ± 27 vs. AID: 66% ± 39%, P = 0.320), and TAR (UP: 37 ± 34 vs. AID: 31% ± 41%, P = 0.604) were similar between arms. A proportionately low number of people experienced exercise-induced hypoglycemia (UP: n = 2 vs. AID: n = 1, P = 1.00). In conclusion, switching to AID therapy did not alter patterns of glycemia around sustained moderate-intensity exercise in adults with T1D. Clinical Trial Registration number: NCT05133765.

Metabolic and physiological responses to graded exercise testing in individuals with type 1 diabetes using insulin pump therapy.

AIMS: To profile acute glycaemic dynamics during graded exercise testing (GXT) and explore the influence of glycaemic indicators on the physiological responses to GXT in adults with type 1 diabetes using insulin pump therapy. METHODS: This was a retrospective analysis of pooled data from four clinical trials with identical GXT protocols. Data were obtained from 45 adults with type 1 diabetes using insulin pumps [(30 females); haemoglobin A1c 59.5 ± 0.5 mmol/mol (7.6 ± 1.0%); age 49.7 ± 13.0 years; diabetes duration 31.2 ± 13.5 years; V̇O2peak 29.5 ± 8.0 ml/min/kg]. Integrated cardiopulmonary variables were collected continuously via spiroergometry. Plasma glucose was obtained every 3 min during GXT as well as the point of volitional exhaustion. Data were assessed via general linear modelling techniques with age and gender adjustment. Significance was accepted at p ≤ .05. RESULTS: Despite increasing duration and intensity, plasma glucose concentrations remained similar to rest values (8.8 ± 2.3 mmol/L) throughout exercise (p = .419) with an overall change of +0.3 ± 1.1 mmol/L. Starting glycaemia bore no influence on subsequent GXT responses. Per 1% increment in haemoglobin A1c there was an associated decrease in V̇O2peak of 3.8 ml/min/kg (p < .001) and powerpeak of 0.33 W/kg (p < .001) concomitant with attenuations in indices of peripheral oxygen extraction [(O2 pulse) -1.2 ml/beat, p = .023]. CONCLUSION: In adults with long-standing type 1 diabetes using insulin pump therapy, circulating glucose remains stable during a graded incremental cycle test to volitional exhaustion. Glycaemic indicators are inversely associated with aerobic rate, oxygen economy and mechanical output across the exercise intensity spectrum. An appreciation of these nexuses may help guide appropriate decision making for optimal exercise management strategies.

Influence of exercise amount and intensity on long-term weight loss maintenance and skeletal muscle mitochondrial ROS production in humans.

Sustaining a weight loss after a lifestyle intervention is challenging. The objective of the present study was to investigate if mitochondrial function is associated with the ability to maintain a weight loss. Sixty-eight former participants in an 11-12-week lifestyle intervention were recruited into 2 groups; weight loss maintenance (WLM; body mass index (BMI): 32 ± 1 kg/m2) and weight regain (WR; BMI: 43 ± 2 kg/m2) based on weight loss measured at a follow-up visit (WLM: 4.8 ± 0.4; WR: 7.6 ± 0.8 years after lifestyle intervention). Maximal oxygen consumption rate, physical activity level, and blood and muscle samples were obtained at the follow-up experiment. Mitochondrial respiratory capacity and reactive oxygen species (ROS) production were measured. Fasting blood samples were used to calculate glucose homeostasis index. WR had impaired glucose homeostasis and decreased maximal oxygen uptake and physical activity level compared with WLM. The decreased physical activity in WR was due to a lower activity level at vigorous and moderate intensities. Mitochondrial respiratory capacity and citrate synthase (CS) activity was higher in WLM, but intrinsic mitochondrial respiratory capacity (mitochondrial respiratory capacity corrected for mitochondrial content (CS activity)) was similar. ROS production was higher in WR compared with WLM, which was accompanied by a decreased content of antioxidant proteins in WR. Intrinsic mitochondrial respiratory capacity in skeletal muscle is not associated with the ability to maintain a long-term weight loss. WLM had a higher maximal oxygen uptake, physical activity level, mitochondrial respiratory capacity and CS activity compared with WR. The reduced glucose tolerance was concurrent with increased ROS production per mitochondria in WR, and could also be associated with the lower physical activity level in this group.