Using continuous glucose monitoring to prescribe an exercise time: a randomised controlled trial in adults with type 2 diabetes

PURPOSE: Growing evidence suggests the exercise timing, time-of-day it is performed, is important for maximizing glycemic benefits in type 2 diabetes (T2D). This randomized controlled trial investigated the impact of utilizing continuous glucose monitoring to personalise exercise timing on peak hyperglycaemia and cardiometabolic health in people with T2D. METHODS: ) were randomized to eight weeks: i) waitlist control (CTL, eight week CTL then re-randomized to interventions), ii) 22-min daily exercise beginning ∼ 30 min before peak hyperglycemia (ExPeak) or iii) 22-min daily exercise ∼ 90 min after peak hyperglycemia (NonPeak). Time of peak hyperglycemia was pre-determined for each participant using the median of a 14-d habitual continuous glucose monitoring (CGM) period. Glycemic control (HbA1c [primary outcome], CGM), vascular function (flow-mediated dilation [FMD]), arterial stiffness, blood pressure) and body composition were assessed. Linear mixed models compared changes across time between groups. RESULTS: There was no intervention effect for HbA1c, however there was a significant interaction for changes in 24-h peak glucose and %FMD between groups. Compared to CTL, both intervention groups significantly lowered peak glucose (ExPeak: 95 %CI: -2.0 to -0.3 mmol/L, NonPeak: CI: -2.3 to -0.6 mmol/L) and %FMD increased (ExPeak: 95 %CI: 0.6 to 1.5 %, NonPeak: 95 %CI: 0.0 to 1.1 %). Adherence to interventions was high for both intervention groups (>90 %). CONCLUSION: Prescribing exercise to target peak hyperglycemia did not improve HbA1c; however cardiometabolic health outcomes improved in both groups prescribed an exercise time compared to control. Personalizing exercise prescription by prescribing a time to exercise may be a novel approach to improve health outcomes and physical activity participation.