Impact of ß-blocker treatment and nutritional status on glycemic response during exercise in patients with type 2 diabetes

Most individuals with type 2 diabetes are affected by hypertension and thus have higher risk of cardiac complications. In addition to behavioural modifications, such as healthy food choices and regular physical activity, beta-blocker treatment may be considered to reduce morbidity and mortality, especially after a cardiovascular event. However, this medication is generally associated with a deleterious impact on glucose metabolism. The objective of the study was to assess the impact of beta-blocker treatment on glucose response during exercise in patients with type 2 diabetes, free of cardiovascular complications. Ten sedentary men, treated with diet and/or hypoglycemic agents have performed four exercise sessions at 60% of their V O2peak, in the fasted state or 2 hours following a standardized breakfast, with and without beta-blockers (atenolol 100 mg id for five consecutive days). Blood samples were drawn during the resting period, at 15-min intervals during the exercise session and during the recovery period. A reduction of blood glucose levels was observed following the exercise session in the postprandial state (48% and 44% reduction with and without beta-blockers respectively; P < 0.001). One hour of exercise performed in the fasted state had a minimal impact on glucose and insulin levels, whether with or without beta-blockers. beta-blocker treatment was not associated with increased baseline blood glucose or insulin levels in the fasted or the postprandial situation. Dietary status has a more important impact on plasma glucose and insulin modulation than short-term use of beta-blockers.