Beta-adrenoceptor-blocking drugs and blood sugar control in diabetes mellitus.

Abstract

Summary and conclusionsThe effects on diabetic control of the relative cardioselective beta-blocker metoprolol and the non-selective drug propranolol were compared in 20 hypertensive diabetic patients receiving diet alone or diet and oral hypoglycaemic agents. Each drug was given for one month in a double-blind, cross-over study. Fasting, noon, and mid-afternoon blood sugar concentrations rose by 1-0-1-5 mmol/l (18-27 mg/100 ml). The rise with propranolol was not significantly greater than with metoprolol. In a few patients the rise was clinically important.The small overall change observed in diabetic control should not deter the use of beta-blockers in non-insulindependent diabetics, provided control is carefully monitored at the onset of treatment. IntroductionCatecholamines play a part in the release of insulin' and in the clinical reaction to hypoglycaemia2 and metabolic recovery from it.3 Adrenoceptor-blocking drugs might therefore be expected to influence the way in which patients, particularly diabetics, respond to fluctuations in blood sugar concentrations. Studies on volunteers4-6 show that beta-blockers modify the recovery from hypoglycaemia and suggest that selective, beta1-blocking drugs interfere less than non-selective drugs. The possible metabolic effects of beta-blockers in the presence of a high blood sugar concentration, however, have received relatively little attention, though one study7 showed that glucose tolerance is impaired to a greater extent with non-selective than cardioselective betablockers. One explanation for these results is that insulin secretion may be influenced through a beta 2-receptor in man as it is in dogs.8 The relevance of these observations to the routine management of diabetes is unknown.We decided to see whether long-term treatment with a betablocker materially affects blood sugar control in maturity-onset diabetes and if any advantage is gained from choosing a cardioselective agent. With these aims we compared the relatively cardioselective beta-blocker metoprolol9 with the non-selective agent propranolol in patients with maturity-onset diabetes.

Pharmacological Agents That Directly Modulate Insulin Secretion

“…Twenty type 2 diabetic subjects treated with ␤-blockade for 4 weeks were reported to have increased blood glucose levels of 25 mg/dl compared with placebo-controls (Wright et al, 1979). Importantly, insulin levels were apparently unaltered with treatment, suggesting that the observed effect on blood glucose was not due to decreased insulin secretion.…”

Antihypertensive Therapy and Incidence of Type 2 Diabetes

“…␤-Blockade has been shown to inhibit both pancreatic insulin secretion (via ␤ 2 -receptors) and peripheral glucose utilization (43)(44)(45)(46). Weight gain, diminished peripheral blood flow, and unopposed stimulation of ␣ 2 -receptor-mediated glycogenolysis have been proposed as additional potential diabetogenic mechanisms (43,47,48). ␤-Blockers with intrinsic sympathomimetic effects and ␤ 1 -selective blockers with ␤ 2 -agonist properties appear to have minimal detrimental (and possibly beneficial) effects on glycemic control (9,47).…”

Treating hypertension while protecting the vulnerable islet in the cardiometabolic syndrome

“…They induce weight gain, decrease skeletal muscle blood flow, and may exert a detrimental effect on glycemic control by enhancing α 2 -receptor-mediated hepatic glucose output [82,92,93,97,103,104,106,107]. Older β-blockers also worsen lipid levels [106].…”

“…First-and second-generation β-blockers decrease insulin sensitivity, inhibit first-phase pancreatic insulin secretion (via β 2 -receptors), decrease peripheral glucose utilization, and decrease insulin clearance [92,93,97,103,104,106,107]. They induce weight gain, decrease skeletal muscle blood flow, and may exert a detrimental effect on glycemic control by enhancing α 2 -receptor-mediated hepatic glucose output [82,92,93,97,103,104,106,107].…”