Effects of aerobic and resistance training on hemoglobin A1c levels in patients with type 2 diabetes: A randomized controlled trial

Abstract

Context: Exercise guidelines for individuals with diabetes include both aerobic and resistance training although few studies have directly examined this exercise combination. Objective: To examine the benefits of aerobic training alone, resistance training alone, and a combination of both on hemoglobin A 1c (HbA1c) in individuals with type 2 diabetes. Design, Setting, and Participants: A randomized controlled trial in which 262 sedentary men and women in Louisiana with type 2 diabetes and HbA1c levels of 6.5% or higher were enrolled in the 9-month exercise program between April 2007 and August 2009. Intervention: Forty-one participants were assigned to the nonexercise control group, 73 to resistance training 3 days a week, 72 to aerobic exercise in which they expended 12 kcal/kg per week; and 76 to combined aerobic and resistance training in which they expended 10 kcal/kg per week and engaged in resistance training twice a week. Main Outcome: Change in HbA 1c level. Secondary outcomes included measures of anthropometry and fitness. Results: The study included 63.0% women and 47.3% nonwhite participants who were a mean (SD) age of 55.8 years (8.7 years) with a baseline HbA 1c level of 7.7% (1.0%). Compared with the control group, the absolute mean change in HbA1c in the combination training exercise group was -0.34% (95% confidence interval [CI], -0.64% to -0.03%; P=.03). The mean changes in HbA1c were not statistically significant in either the resistance training (-0.16%; 95% CI, -0.46% to 0.15%; P=.32) or the aerobic (-0.24%; 95% CI, -0.55% to 0.07%; P=.14) groups compared with the control group. Only the combination exercise group improved maximum oxygen consumption (mean, 1.0 mL/kg per min; 95% CI, 0.5-1.5, P