Glucose-lowering effects of physical activity in type 1 diabetes: A causal modelling and matched-pair analysis...

To evaluate the acute glucose-lowering effect of bouts of physical activity (PA) for hyperglycaemia in individuals with type 1 diabetes, using a within-subject matched-pairs causal design to approximate the control condition of no activity.

Data comprised 1546 PA bouts of 10-30 min from 482 participants in the T1DEXI and T1DEXIP cohorts where glucose was >10 mmol/L. Each PA bout was matched [starting glucose, glucose rate of change, insulin on board (IOB) and glucose variability (CV)] to a matched non-PA period within the same individual using a weighted k-nearest neighbours algorithm (SMD <0.01).

Change in glucose from PA onset to 20 min post-activity.

Predictors of glucose response and rate of hypoglycaemia incidence.

PA [median 23 min: IQR (20, 30)] led to a mean glucose change of -2.2 mmol/L (p < 0.001), compared with 0.3 mmol/L (p < 0.001) during matched non-PA periods (mean difference: -1.9 mmol/L (p < 0.0001)). No significant differences by age, activity type or intensity were observed. The strongest predictors of PA-induced glucose change were (in order) glucose rate of change, starting glucose, CV, duration and IOB. A heatmap using starting glucose and glucose rate of change was developed to guide real-time decision-making. PA-induced hypoglycaemia risk was very low (<2%).

Using PA to lower high glucose levels is an effective and safe strategy, and when guided by CGM, it can become a personalised tool for type 1 diabetes education.