Relationship Between Moderate-to-Vigorous Physical Activity and Glycemia Among Young Adults with Type 1 Diabetes and Overweight or Obesity: Results from the Advancing Care for Type 1 Diabetes and Obesity Network (ACT1ON) Study.

Aims: Using data from the ACT1ON study, we conducted secondary analyses to assess the relationship between minutes of moderate-to-vigorous physical activity (MVPA) and glycemia in adults with type 1 diabetes (T1D) and overweight or obesity. Materials and Methods: Participants (n = 66) with T1D provided measures of glycemia (hemoglobin A1c [HbA1c], percent of time below range <70 mg/dL, time-in-range [TIR 70-180 mg/dL], and time above range [TAR >180 mg/dL]) and self-reported physical activity (Global Physical Activity Questionnaire [GPAQ] and Previous Day Physical Activity Recalls [PDPAR]) at baseline, 3, 6, and 9 months postintervention. Wearable activity data were available for a subset of participants (n = 27). Associations were estimated using mixed effects regression models adjusted for design, demographic, clinical, and dietary covariates. Results: Among young adults 19-30 years of age with a baseline HbA1c of 7.9% ± 1.4% and body mass index of 30.3 (interquartile range 27.9, 33.8), greater habitual weekly MVPA minutes were associated with higher HbA1c through the GPAQ (P < 0.01) and wearable activity data (P = 0.01). We did not observe a significant association between habitual MVPA and any continuous glucose monitoring metrics. Using PDPAR data, however, we observed that greater daily MVPA minutes were associated with more TAR (P < 0.01) and reduced TIR (P < 0.01) on the day following reported physical activity. Conclusions: Among young adults with T1D and overweight or obesity, increased MVPA was associated with worsened glycemia. As physical activity is vital to cardiovascular health and weight management, additional research is needed to determine how to best support young adults with T1D and overweight or obesity in their efforts to increase physical activity. Clinical Trial Registration number: NCT03651622.