Rationale and Objectives:
Individuals with Type 2 diabetes mellitus (T2DM) have low fitness and typically present with elevated risk factors for cardiovascular disease. In several small controlled studies, endurance and resistance training have been shown to improve fitness and glycemic control. Cohort studies have furthermore suggested a strong relationship between fitness and cardiovascular complications and mortality. Exercise is therefore advocated as a core intervention for persons with T2DM - unfortunately physical activity is actually adopted only sporadically. In our community we felt that development of a formal exercise program in partnership with diabetes centers patterned after a cardiac rehab model could address this care gap. The present study examines the effect of a 6 month structured exercise program on measures of fitness and risk factors in T2DM.
Methods:
385 consecutive men and women (mean age 56, 56% women) previously diagnosed with T2DM (mean duration 6 years) enrolled in this program contributed data for this analysis. After an initial cardiopulmonary exercise assessment with direct VO2 measure, subjects were prescribed an exercise program consisting of walking 3-5 days/week at 50-85% heart rate reserve for 20-60 minutes per session. They also engaged in light resistance training towards the end of their 6 months. Fasting blood glucose (FBG), hemoglobin A1C, LDL and HDL cholesterol were measured along with VO2peak and body composition (BMI, % body fat (BF), waist circumference) pre- and post- six months training. Effects of training on VO2peak and body composition were examined with Student's paired t- tests using SPSS 13.0. Changes in glucose and lipids at baseline, 3 and 6 months were examined using an analysis of variance. Data are presented as means +/- standard deviation.
Results:
Average walking prescriptions increased from 1.1 miles in 22 mins at baseline to 2.2 miles in 39 mins at 6 mos. Following training, cardiovascular fitness improved significantly (pre: 18.1 +/- 0.4 ml [middle dot] kg-1 [middle dot] min-1; post: 20.5 +/- 0.6 ml [middle dot] kg-1 [middle dot] min-1; P < 0.001). BMI, %BF, and waist circumference demonstrated significant reductions (BMI: pre: 32.0 +/- 6 kg/m2; post: 31.6 +/- 6; P < 0.001; %BF: 35.6 +/- 9.7; post: 34.4 +/- 0.9; P < 0.001; Waist: pre: 103 +/- 1.3 cm; post: 101 +/- 1.3 cm; P < 0.001). LDL cholesterol fell significantly over 6 months without any modification in lipid medication (pre: 2.84 +/- 1.04; 3 mos: 2.57 +/- 0.79; 6 mos: 2.47 +/- 0.78; P = 0.03), whereas HDL was fairly high at baseline and was unchanged (pre: 1.20 +/- 0.35; post: 1.31 +/- 0.39; P = N.S.). Both FBG and A1C improved significantly (FBG: pre: 8.1 mmol/l +/- 3.0; 3 mos: 7.4 +/- 2.0; post: 7.0 +/- 1.8; P = 0.02; A1C: pre: 7.3 mmol/l +/- 1.5; 3 mos: 6.8 +/- 1.3, post: 6.6 +/- 0.8 mmol/l; P = 0.002). Doses of diabetes medications were reduced over this period.
Conclusions:
Type 2 diabetes represents a coronary equivalent in future risk and prognosis. Participation in a structured exercise program patterned after a cardiac model is an effective intervention in appreciably modifying this risk.
Section Description
For more information, contact Marilyn Thomas (204) 488-5854