Reproducibility of plasma glucose responses to moderate‐intensity exercise in individuals with type 1 diabetes

Aim To examine the within‐person variability in plasma glucose responses to moderate‐intensity morning exercise in young individuals with type 1 diabetes after overnight fasting and under basal insulin conditions. Methods In this pilot study, eight participants completed 40 min of moderate‐intensity exercise at 60% V̇O2 peak on three separate days. The within‐person standard deviation (SDw) in plasma glucose response was analysed both during and 1 h after exercise using the two visits per participant most closely matched by pre‐exercise plasma glucose level. Results When the two closest matched visits per individual were included for analysis, mean (±SD) change in plasma glucose level was −1.8 ± 1.1 mmoL/L during exercise and −0.6 ± 1.0 mmoL/L during recovery, with the SDw of these changes being 0.5 mmol (95% CI 0.2, 0.8) during exercise and 0.8 mmoL/L (95% CI 0.4, 1.3) during recovery. The median intra‐individual difference in plasma glucose level change was 0.3 mmoL/L [IQR 0.1, 0.7] during exercise and 0.8 mmoL/L [IQR 0.4, 1.0] during recovery. Conclusion Within‐person plasma glucose responses to moderate‐intensity exercise may be reproducible under fasting and basal insulin conditions and similar pre‐exercise plasma glucose levels. This finding may assist the design of future studies investigating both the reproducibility of glycaemic responses to exercise and blood glucose management for individuals with type 1 diabetes.