Exercise and 24-h Glycemic Control: Equal Effects for All Type 2 Diabetes Patients?

VAN DIJK, J.-W., R.J.F. MANDERS, E. E. CANFORA, W. VAN MECHELEN, F. HARTGENS, C. D. A. STEHOUWER, and L. J. C. VAN LOON. Exercise and 24-hGlycemic Control: Equal Effects for All Type 2 Diabetes Patients? Med. Sci. Sports Exerc., Vol. 45, No. 4, pp. 628-635, 2013. Purpose: We assessed the effect of a single bout of moderate-intensity exercise on subsequent 24-h glycemic control in 60 type 2 diabetes patients. Moreover, we examined whether individual responses to exercise were related to subjects' baseline characteristics, including age, body mass index, diabetes duration, exercise performance, medication, and HbA(1c) content. Methods: Sixty type 2 diabetes patients (insulin-treated, n = 23) participated in a randomized crossover experiment. Patients were studied on two occasions for 3 d under strict dietary standardization but otherwise free-living conditions. Parameters of glycemic control (means [95% confidence interval]) were assessed by continuous glucose monitoring over the 24-h period after a single bout of moderate-intensity endurance-type exercise or no exercise at all (control). Results: Type 2 diabetes patients experienced hyperglycemia (blood glucose >10 mmol.L-1) for as much as 8:16 h:min (6:44 to 9:48 h:min) per day. The prevalence of hyperglycemia was reduced by 31% to 5: 38 h: min (3: 17 to 7: 00 h: min) over the 24-h period after the exercise bout (P <0.001). Moreover, exercise lowered average blood glucose concentrations by 0.9 mmol.L-1 (0.7 to 1.2) and reduced glycemic variability (P <0.05). The response to exercise showed considerable variation between subjects and correlated positively with HbA(1c) levels (r = 0.38, P <0.01). Nevertheless, even well-controlled patients with an HbA(1c) level below 7.0% (n = 28) achieved a 28% reduction in the daily prevalence hyperglycemia after exercise (P <0.01). Conclusions: A single bout of moderate-intensity exercise substantially improves glycemic control throughout the subsequent day in insulin- and non-insulin-treated type 2 diabetes patients. Of all baseline characteristics, only subject' HbA(1c) level is related to the magnitude of response to exercise. Nevertheless, the present study demonstrates that even well-controlled patients benefit considerably from the blood glucose-lowering properties of daily exercise.