Quantifying the Acute Changes in Glucose with Exercise in Type 1 Diabetes: A Systematic Review and Meta-Analysis

Background The acute impact of different types of physical activity on glycemic control in type 1 diabetes has not been well quantified. Objectives Our objective was to estimate the rate of change (RoC) in glucose concentration induced acutely during the performance of structured exercise and at recovery in subjects with type 1 diabetes. Methods We searched for original articles in the PubMed, MEDLINE, Scopus, and Cochrane databases. Search terms included type 1 diabetes, blood glucose, physical activity, and exercise. Eligible studies (randomized controlled trials and non-randomized experiments) encompassed controlled physical activity sessions (continuous moderate [CONT], intermittent high intensity [IHE], resistance [RESIST], and/or a resting reference [REST]) and reported excursions in glucose concentration during exercise and after its cessation. Data were extracted by graph digitization to compute two RoC measures from population profiles: RoC(E) during exercise and RoC(R) in recovery. Results Ten eligible studies were found from 540 publications. Meta-analyses of exercise modalities versus rest yielded the following: RoC(E) -4.43 mmol/L h(-1) (p < 0.00001, 95% confidence interval [CI] -6.06 to -2.79) and RoC(R) +0.70 mmol/L h(-1) (p = 0.46, 95% CI -1.14 to +2.54) for CONT vs. REST; RoC(E) -5.25 mmol/L.h(-1) (p < 0.00001, 95% CI -7.02 to -3.48) and RoC(R) +0.72 mmol/L h(-1) (p = 0.71, 95% CI -3.10 to +4.54) for IHE vs. REST; RoC(E) -2.61 mmol/L h(-1) (p = 0.30, 95% CI -7.55 to +2.34) and RoC(R) -0.02 mmol/L h(-1) (p = 1.00, 95% CI -7.58 to +7.53) for RESIST vs. REST. Conclusions Novel RoC magnitudes RoC(E), RoC(R) reflected rapid decays of glycemia during CONT exercise and gradual recoveries immediately afterwards. RESIST showed more constrained decays, whereas discrepancies were found for IHE.