Baseline characteristics of the participants.

Background
Studies suggest that longer durations of T2DM increase the risk of T2DM complications and premature mortality. However, whether T2DM duration impacts the efficacy of an aerobic exercise intervention is unclear.
Objective
The purpose of this study was: 1) to compare changes in body composition, cardiorespiratory fitness, and glycemia between individuals with short- and long-duration T2DM after aerobic exercise and 2) to determine whether these changes were associated with changes in glycemia by T2DM duration.
Methods
A secondary analysis of the INTENSITY study (NCT03787836), including thirty-four adults (≥19 years) with T2DM who participated in 28 weeks of aerobic exercise training for 150 minutes per week at a moderate-to-vigorous intensity (4.5 to 6.0 metabolic equivalents (METs)). Using pre-established cut-points, participants were categorized into two groups 1) short-duration T2DM (<5 years) or 2) long-duration T2DM (≥5 years). Glycemia was measured by glycated hemoglobin (HbA1c), body composition by BodPod, and cardiorespiratory fitness by a measure of peak oxygen consumption (VO2peak). All measurements were performed at baseline, 16 weeks, and 28 weeks.
Results
Participants in the short-duration T2DM group experienced decreases in fat mass (kg) (p = 0.03), HbA1c (p = 0.05), and an increased relative VO2peak (p = 0.01). Those with long-duration T2DM experienced decreases in fat mass (kg) (p = 0.02) and HbA1c (p <0.001) and increased fat-free mass (p = 0.02). No significant differences were observed between groups in any outcomes. Changes in fat mass (r = 0.54, p = 0.02), and body fat percentage (r = 0.50, p = 0.02) were significantly associated with the change in HbA1c in those with a long-duration T2DM only.
Conclusion
Our results suggest T2DM duration did not differently impact the efficacy of a 28-week aerobic exercise intervention. However, changes in body composition were associated with better glycemia in individuals with longer T2DM duration only.