The Type 1 Diabetes and EXercise Initiative (T1DEXI): Examining the acute glycemic effects of different types of structured exercise sessions in type 1 diabetes in a real-world setting

Objective: Maintenance of glycemic control during and following exercise remains a major challenge for individuals with type 1 diabetes. Glycemic responses to exercise may differ by exercise type (aerobic, interval, resistance), and the effect of activity type on glycemic control following exercise remains unclear.

Research Design-Methods: The Type 1 Diabetes Exercise Initiative (T1Dexi) was a real-world study of at-home exercise. Adult participants were randomly assigned to complete six structured aerobic, interval, or resistance exercise sessions over 4-weeks. Participants self-reported study and non-study exercise, food intake, and insulin dosing (multiple-daily injection [MDI] users) using a custom smart phone application, and provided pump data (pump users), heart rate, and continuous glucose monitoring (CGM) data.

Results: 497 adults with type 1 diabetes, mean±SD age 37±14 years, HbA1c 6.6±0.8% (49±8.7 mmol/mol) assigned to structured aerobic (N=162), interval (N=165), or resistance (N=170) exercise were analyzed. Mean change in glucose during assigned exercise was -18±39, -14±32, and -9±36 mg/dL for aerobic, interval, and resistance, respectively (P<0.001), with similar results for closed loop, standard pump, and MDI users. Time-in-range 70-180 mg/dL [3.9-10.0 mmol/L] was higher during the 24-hours following study exercise when compared to days without exercise (76±20% vs. 70±23%; P<0.001).

Conclusion: Adults with type 1 diabetes experienced the largest drop in glucose level with aerobic followed by interval and resistance exercise, regardless of insulin delivery modality. Even in well controlled adults with type 1 diabetes, days with structured exercise sessions contributed to clinically meaningful improvement in glucose time-in-range but may have slightly increased time below range.