A large observational cohort analysis published in the Diabetologia assessed the glycemic impact of three exercise modalities, walking (WALK), aerobic excluding walking (AER), and anaerobic (ANAER), in 3248 users of mySugr Logbook and Apple Health with type 1 diabetes. Participants had a mean±SD age of 41.23±12.25 years, glucose management index (GMI) of 7.05±1.09%, and 41.5% were female. Data were derived from 428,058 recorded exercise sessions.

Independent of exercise type, glucose decreased by −1.06±0.89 mmol/l (p<0.001). Individually, WALK reduced glucose by −1.24±0.81 mmol/l, AER by −1.43±1.02 mmol/l, and ANAER by −0.52±0.81 mmol/l (all p<0.001). Compared with sedentary days, time in range (3.9–10 mmol/l) increased by +2.08±6.06% for WALK, +2.94±6.46% for AER, and +3.93±7.16% for ANAER (all p<0.001). Time below range (<3.9 mmol/l) increased by 0.37±1.57% (WALK), 0.74±1.70% (AER), and 0.68±1.79% (ANAER) (all p<0.001).

ANAER was associated with a smaller chance of acute hypoglycemia, while WALK was associated with a smaller chance of nocturnal hypoglycemia (p<0.001). Exercise performed after 15:30 hours did not increase nocturnal hypoglycemia risk compared with earlier sessions (+0.9±0.34%; p<0.01).

As an observational real-world data analysis, causality cannot be inferred. The findings describe population-level associations between exercise modality and glycemic patterns.