Combined Effects Of Aerobic And Resistance Exercise On HbA_1c In Type 2 Diabetic Us Veterans

PURPOSE: According to the Centers for Disease Control (CDC), more than 37 million Americans have type 2 diabetes mellitus (T2D). Some studies suggest that the combination of aerobic exercise with resistance exercise may be more effective in regulating blood glucose regulation in T2D patients as compared to either mode independently. However, information on the combined effects of aerobic and resistance exercise training on hemoglobin A1C (HbA1C) levels is limited. Thus, the purpose of this study was to examine the effects of combined exercise on HbA1C changes in T2D US Veterans. In addition, we aimed to determine if baseline HbA1C level influenced the magnitude of effect of combined exercise. METHODS: Prospective waitlist-controlled intervention study in US Veterans with T2D (n = 458, EX = 344, CON = 114; age, 59 ± 8 years; HbA1C, 8.5 ± 1.6%; BMI, 35.2 ± 22.5 kg·m2). US Veterans were enrolled in an exercise program consisting aerobic and resistance exercise training. Aerobic exercise was performed for 20-40 minutes at 50-80% heart rate reserve. Resistance exercise was performed for all major muscle groups for 2-3 sets of 12-15 repetitions. Exercise duration was 12-16 weeks with a frequency of 3 times per week. Participants were grouped according to their baseline HbA1C levels using the cut point of 7.5%. Main outcome was change in HbA1C levels from baseline to post-exercise. Data were analyzed using a linear mixed model with an interaction between treatment (EX and CON) and baseline HbA1C levels (<7.5% and > 7.5%). Covariates included age and change in BMI. Significance was set at P < 0.05 (2-tailed). RESULTS: There was a significant interaction between treatment group and baseline HbA1C levels (F1, 452.0 = 4.86, p = 0.03). Mean changes in HbA1C following combined exercise were significantly greater in Veterans with HbA1C > 7.5% (-1.295) compared to those with HbA1C < 7.5% (-0.31; mean difference = 0.99) p < 0.001). There were no differences in HbA1C levels within the CON group (mean difference = 0.35; p = 0.17). CONCLUSION: The combination of aerobic and resistance exercise improved HbA1C levels in US Veterans with T2D. Greater improvements were observed in those with baseline HbA1C levels >7.5%.