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

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.

Adults with T2D (HbA1c: 7.2 ± 0.8 %; Age: 63 ± 12 y; BMI: 29 ± 5 kg/m²) 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.

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 %).

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.