Effects Of Exercise Training With And Without Weight Loss On Oral Disposition Index In STRRIDE-PD

Abstract

PURPOSE To determine the effects of aerobic exercise training with and without weight loss on oral disposition index (DIo) - a composite measure of β-cell function associated with future diabetes risk - in previously sedentary adults with prediabetes. METHODS Participants (n = 157) were enrolled in the Studies of a Targeted Risk Reduction Intervention through Defined Exercise-Prediabetes (STRRIDE-PD) randomized trial. Participants completed one of four 6-month interventions: 1) Low Amount/Moderate Intensity (LM): 10 kcal exercise expenditure/kg body weight/week (KKW) at 50% VO2reserve; 2) High Amount/Moderate Intensity (HM): 16 KKW at 50% VO2reserve; 3) High Amount/Vigorous Intensity (HV): 16 KKW at 75% VO2reserve; 4) Clinical Lifestyle (CL): same as LM plus diet and 7% weight loss. Following an overnight fast, 75-g oral glucose tolerance tests with blood samples taken at 0, 30, 60, 90, and 120 min were administered at baseline and 16-24 hours post-training. DIo was calculated as Δinsulin0-30 min/Δglucose0-30 min × 1/fasting insulin. Wilcoxon signed-rank tests were used to determine whether the post- minus pre-intervention change score within each group was significant (p < 0.05). A Kruskal-Wallis test was used to determine difference among groups. Baseline values reported as median (interquartile range); within-group change scores reported as mean difference (95% confidence interval). RESULTS At baseline, there were no significant differences among groups for DIo [median values ranged from 1.97 (3.00) mM-1 for LM to 2.48 (3.14) mM-1 for HV]. After 6 months of exercise training, only the CL group significantly improved DIo [0.71 (0.28-1.15) mM-1;p = 0.002]. Within-group changes for the exercise-only groups were 0.10 (-0.68-0.87) mM-1 for LM; -0.19 (-0.73-0.34) mM-1 for HM; and -0.41 (-0.83-0.02) mM-1 for HV. The Kruskal-Wallis test revealed changes in DIo were significantly better for the CL group compared to both high amount groups. CONCLUSIONS For adults with prediabetes, combining a dietary intervention and weight loss with aerobic exercise improves DIo. Compared to findings from previous STRRIDE studies, improving β-cell function appears to be more challenging with aerobic exercise alone for those with a glycemic status closer to type 2 diabetes. Supported by NIH R01DK081559