ABSTRACT
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, HbA1c 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.
Subject(s)
Blood Glucose/metabolism , Diabetes Mellitus, Type 1/blood , Hypoglycemia/blood , Adult , Cross-Over Studies , Exercise/physiology , Female , Humans , Male , Middle Aged , Postprandial Period , Single-Blind MethodABSTRACT
OBJECTIVES: To compare the effect of low-volume HIIT to moderate-intensity aerobic training (MICT) on fat mass, cardiometabolic profile and physical capacity and confirm its feasibility in older women. METHODS: Inactive older women (60-75 years) were randomly assigned to 8 weeks of either HIIT (75 min/week; n=9) or MICT (150 min/week; n=9). Body composition, fasting metabolic profile, cardiovascular risk (Framingham score), and physical capacity (senior fitness test, VO2peak) were assessed before and after the intervention. Feasibility was evaluated with completion rate (training compliance; dropout rate) and affective response (Feeling scale; pre- and post-exercise). RESULTS: Total cholesterol, non-HDL-C levels and the Framingham risk score decreased in both groups (all p≤0.03). Although VO2peak remained unchanged, the 6MWT distance increased (p<0.0001), irrespective of the group. Completion rate and affective responses were not different between groups (all p≥0.38). CONCLUSION: A short-term HIIT program is feasible and provides as much benefits as MICT in older women.
