Effect of Exercise Training Intensity on Glycemic Control in Older Adults with Prediabetes

Abstract

INTRODUCTION: Older adults have the highest rates of prediabetes and diabetes in the US. Exercise is a well-established method to improve glycemic control, however, the optimal dose (duration and intensity) of exercise required to improve glycemic control among older adults is unclear. PURPOSE:To compare the effect of 12 weeks of moderate vs. high intensity exercise training on daily glycemic control in older adults with prediabetes. METHODS: 15 older adults (66.4 ±5.1 yrs) with prediabetes (HbA1c 5.7-6.4% or fasting glucose 100-125 mg/dl) participated in a 12-week supervised aerobic exercise training intervention. Participants were screened prior to being randomized to the moderate (MOD: 60-65% HRmax) or vigorous (VIG: 80-85% HRmax) intensity training group. During the intervention, participants exercised 4 days per week (45 minutes/session) in their target heart rate range. Continuous glucose monitors (CGM) were worn for 1 week at baseline and during the 12thweek of supervised exercise training. Daily glycemic control was quantified over 24 hour periods (00:00 to 23:29) for each day the CGMs were worn during the week at baseline and after exercise training. We calculated mean, total area under the curve (trapezoidal method), and duration of hyperglycemia (percent time glucose ≥140mg/dL). Using linear mixed models with repeated measures, we determined the effect of exercise training and whether the effect of training varied by exercise intensity group. Significance was set at p < 0.05. Data are reported as mean±SD. SUMMARY OF RESULTS: There were no significant differences in any baseline participant characteristics (e.g. sex, age, BMI) between exercise training groups. At baseline, VIG had significantly lowermean (MOD: 136.0 ±18.4; VIG: 122.6 ±7.4 mg/dL), total area under the curve (AUC) (MOD: 3243.0 ±505.1; VIG: 2873.4 ±226.2 mg*hr/dL), and duration of hyperglycemia (MOD: 38.5 ±28.6%; VIG: 19.9 ±9.6%). After the intervention, there were no significant changes in mean glucose, AUC, or duration of hyperglycemia in either group. CONCLUSION: Regardless of exercise intensity,12 weeks of aerobic exercise training did not significantly change daily glycemic control in older adults with prediabetes, suggesting that changing other lifestyle factors may be needed to improve glycemic control in this population.