Effect of beta-blocking drugs on beta-cell function and insulin sensitivity in hypertensive non-diabetic patients.
The effects of two beta-blocking drugs on endogenous insulin secretion and insulin sensitivity were investigated in a double-blind cross-over study in 13 hypertensive patients. The patients were randomly allocated to each of three 2-week treatment periods with propranolol 80 mg b.i.d., atenolol 50 mg b.i.d. and placebo b.i.d. Endogenous insulin secretion was assessed by measuring serum insulin and C-peptide before and 6 min after iv administration of glucagon; insulin sensitivity was determined by measuring insulin binding to erythrocytes, and as the glucose disappearance rate (KITT) after i.v. insulin. Fasting concentrations of serum free fatty acids (S-FFA) and plasma gastric inhibitory polypeptide (P-GIP) were also recorded during the three study periods. Both propranolol and atenolol reduced blood pressure, heart rate and S-FFA concentrations compared to placebo, and all patients showed measurable plasma concentrations of propranolol and atenolol. The results can be considered representative, therefore, of clinical beta-blockade. The two drugs did not significantly influence the fasting blood glucose level. There was an increase in fasting and glucagon-stimulated serum C-peptide concentration during propranolol therapy compared with placebo (p = 0.037 and p = 0.030, respectively), although this was not reflected by a significant change in serum insulin. Propranolol and atenolol did not significantly influence insulin binding to erythrocytes, but they clearly reduced the glucose disappearance rate KITT was compared to placebo (p = 0.0036 and p = 0.0003), respectively). The findings support the view that beta-blocking drugs can influence glucose metabolism by mechanisms other than inhibition of endogenous insulin secretion.
D000319:Adrenergic beta-Antagonists / Q000009:adverse effects*; D000328:Adult; D001262:Atenolol / Q000009:adverse effects; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D004311:Double-Blind Method; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D005749:Gastric Inhibitory Polypeptide / Q000097:blood; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D011433:Propranolol / Q000009:adverse effects; D011897:Random Allocation
D000319:Adrenergic beta-Antagonists; D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D001262:Atenolol; D005749:Gastric Inhibitory Polypeptide; D011433:Propranolol