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-h Glycemic 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 HbA1c 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 910 mmolILj1 ) 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 G 0.001). Moreover, exercise lowered average blood glucose concentrations by 0.9 mmolILj1 (0.7 to 1.2) and reduced glycemic variability (P G 0.05). The response to exercise showed considerable variation between subjects and correlated positively with HbA1c levels (r = 0.38, P G 0.01). Nevertheless, even well-controlled patients with an HbA1c level below 7.0% (n = 28) achieved a 28% reduction in the daily prevalence hyperglycemia after exercise (P G 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 subjects_ HbA1c 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.