Effectiveness of a Community-Based Structured Physical Activity Program for Adults With Type 2 Diabetes: A Randomized Clinical Trial

IMPORTANCE The efficacy of physical activity interventions among individuals with type 2 diabetes has been established; however, practical approaches to translate and extend these findings into community settings have not been well explored. OBJECTIVE To test the effectiveness of providing varying frequencies of weekly structured exercise sessions to improve diabetes control. DESIGN, SETTING, AND PARTICIPANTS The IMPACT (Initiate and Maintain Physical Activity in Communities Trial) study was a controlled randomized clinical trial (randomization occurred from October 2016 to April 2019) that included a 6-month, structured exercise intervention either once or thrice weekly vs usual care (UC; advice only). The exercise intervention was conducted at community-based fitness centers. Follow-up visits were conducted in a university research clinic. Participants included adults with type 2 diabetes (hemoglobin A1c [HbA1c] 6.5%-13.0%, not taking insulin, and no precluding health issues). Data analysis was performed from January to April 2022. INTERVENTIONS A once-weekly structured exercise group, a thrice-weekly structured exercise group, or UC. MAIN OUTCOMES AND MEASURES The primary outcome was HbA1c at 6 months. RESULTS A total of 357 participants (143 women [40.1%]) with a mean (SD) age of 57.4 (11.1) years were randomized (119 each to the UC, once-weekly exercise, and thrice-weekly exercise groups). There was no significant difference in HbA1c change by study group in the intention-to-treat analysis at 6 months. Specifically, HbA1c changed by -0.23%(95% CI, -0.48% to 0.01%) in the thriceweekly exercise group and by -0.16%(95% CI, -0.41% to 0.09%) in the once-weekly exercise group. A total of 62 participants (52.1%) in the once-weekly exercise group and 56 participants (47.1%) in the thrice-weekly exercise group were at least 50% adherent to the assigned structured exercise regimen and were included in the per-protocol analysis. Per-protocol analysis showed that HbA1c changed by -0.35%(95% CI, -0.60% to -0.10%; P =.005) at 3 months and by -0.38%(95% CI, -0.65% to -0.12%; P =.005) at 6 months in the thrice-weekly exercise group compared with UC. There was no significant decrease in HbA1c in the once-weekly exercise group. The exercise interventionwas effective in improving self-reported minutes ofmetabolic equivalent tasks perweek for participants in the thrice-weekly exercise group (both overall and per protocol). CONCLUSIONS AND RELEVANCE Although the intervention was not effective in the intention-to-treat analysis, participants in the thrice-weekly exercise group who attended at least 50% of the sessions during the 6-month exercise intervention program improved HbA1c levels at 6 months. Future efforts should focus on improving adherence to thrice-weekly structured exercise programs to meet exercise guidelines.

Automated summary

This study tested the effectiveness of different frequencies of weekly structured exercise in improving diabetes control. The results showed that the thrice-weekly exercise group demonstrated improvements in HbA1c levels at 6 months in the per-protocol analysis. However, there was no significant difference in HbA1c change in the intention-to-treat analysis. Future efforts should focus on improving adherence to thrice-weekly structured exercise programs.