Effects of beta-receptor blockade on carbohydrate metabolism

The effects of beta-blockers on glucose tolerance, insulin secretion and peripheral insulin sensitivity were evaluated by oral glucose tolerance test and euglycaemic insulin technique in six normoglycaemic patients with primary arterial hypertension at the end of 3-week treatments with placebo (one tablet twice daily) and propranolol (80 mg twice daily). Body weight did not change during the study (83 kg at the end of placebo, 83 kg at the end of propranolol), while blood pressure (150 +/- 9/97 +/- 8 mmHg on placebo, 138 +/- 8/89 +/- 8 mmHg on propranolol, P < 0.01) and heart rate (66 +/- 9 beats/min on placebo, 60 +/- 5 beats/min on propranolol, P < 0.05) showed a significant fall on the beta-blocker. No change was observed in glucose tolerance (incremental area for glucose 3462 +/- 1149 mg/dl per min on placebo, 3209 +/- 1695 mg/dl per min on propranolol), insulin secretion (incremental area for serum insulin 7579 +/- 4380 microU/ml per min on placebo, 7934 +/- 4351 microU/ml per min on propranolol) and peripheral insulin sensitivity (metabolic clearance rate 11 +/- 4 ml/kg per min on placebo, 13 +/- 6 ml/kg per min on propranolol). These data support the hypothesis that chronic treatment with adrenergic blocking agents does not induce any significant change in insulin secretion or peripheral insulin sensitivity.