Effects of different exercise programs and minimal detectable changes in hemoglobin A1c in patients with type 2 diabetes

Background: The incidence of diabetes mellitus is increasing worldwide, resulting in a global epidemic. The most common type, the type 2 diabetes mellitus, constitutes of 90-95 % of the cases and is characterized by the action of and/or impaired insulin secretion. Regular exercise is a recommended strategy in several studies and guidelines for type 2 diabetes control and complications associated with it. Therefore, we evaluated and compared the effects of aerobic and strength exercise programs on the glycemic control in patients with type 2 diabetes. Methods: The selected patients were divided into groups which performed moderate strength training (ST) and aerobic training (AT). The study lasted 20 weeks and was divided into two 10 week phases with anthropometric (body mass index, waist, abdomen and hips circumferences, waist/hip ratio) and biochemical (glycemic and lipid profile) assessments at baseline, 10 weeks and 20 weeks. For intra and inter analyses a mixed ANOVA model was used. Individual changes were calculated using the minimum detectable change, based on a 90 % confidence interval. Results: Eleven patients (five men and six women) completed the 20 weeks of training; five from the ST group and six from the AT. No significant changes were observed in any anthropometric variable in either group. Statistically significant differences were found in mean hemoglobin A1c in both groups between baseline (AT: 8.6 +/- 2.5; ST: 9.2 +/- 1.9) and 10 weeks (AT: 7.2 +/- 1.7; ST: 7.9 +/- 1.2) (p = 0.03), and baseline (AT: 8.6 +/- 2.5; ST: 9.2 +/- 1.9) and 20 weeks (AT: 7.5 +/- 1.7; ST: 7.4 +/- 0.9) (p = 0.01). For the minimal detectable changes, 40 % of the ST and 33 % of AT achieved these changes for hemoglobin A1c. Conclusion: Both aerobic and strength exercises can help the metabolic control in patients with type 2 diabetes, even without significant changes in anthropometry over the 20 weeks of training. However, this period was sufficient to cause changes in hemoglobin A1c values and the estimated average glucose, which are important parameters in controlling diabetes, thus signaling an important consequence of adhering to an exercise routine for type 2 diabetic patients.