Effects of Tai Chi on glucose homeostasis and insulin sensitivity in older adults with type 2 diabetes: a randomised double-blind sham-exercise-controlled trial

Background: a large proportion of adults with type 2 diabetes remain sedentary despite evidence of benefits from exercise for type 2 diabetes. Simplified Yang Tai Chi has been shown in one study to have no effect on insulin sensitivity in older adults. However, a modified Tai Chi form, Tai Chi for Diabetes (TCD) has recently been composed, claiming to improve diabetes control. Methods: subjects were randomised to Tai Chi or sham exercise, twice a week for 16 weeks. Primary outcomes were insulin resistance 72 h post-exercise (HOMA2-IR), and long-term glucose control (HbA(1c)). Results thirty-eight subjects (65 +/- 7.8 years, 79% women) were enrolled. Baseline BMI was 32.2 +/- 6.3 kg/ m(2), 84% had osteoarthritis, 76% hypertension, and 34% cardiac disease. There was one dropout, no adverse events, and median compliance was 100 (0 - 100)%. There were no effects of time or group assignment on insulin resistance or HbA(1c) (- 0.07 +/- 0.4% Tai Chi versus 0.12 +/- 0.3% Sham; P = 0.13) at 16 weeks. Improvement in HbA1c was related to decreased body fat (r = 0.484, P = 0.004) and improvement in insulin resistance was related to decreased body fat (r = 0.37, P = 0.03) and central adiposity (r = 0.38, P = 0.02), as well as increased fat-free mass (r = -0.46, P = 0.005). Conclusions: TCD did not improve glucose homeostasis or insulin sensitivity measured 72 h after the last bout of exercise. More intense forms of Tai Chi may be required to produce the body composition changes associated with metabolic benefits in type 2 diabetes.