β-Adrenergic blockade is more effective in suppressing adrenaline-induced glucose production in Type 1 (insulin-dependent) diabetes

To examine whether diabetes affects the ability of β-blockade to suppress adrenaline-stimulated hepatic glucose production, we infused adrenaline with and without propranolol into normal subjects and diabetic patients receiving a constant insulin infusion in basal amounts. In normal subjects, propranolol did not block the transient 50%-60% rise in glucose production during adrenaline infusion. In contrast, propranolol virtually abolished adrenaline-induced hyperglycaemia and glucose production was virtually abolished by propranolol in the diabetic patients, even though they demonstrated an exaggerated response to adrenaline alone (persistent increase in glucose production of 50%-90% above baseline). When insulin was infused together with adrenaline and propranolol in normal subjects in doses exceeding those given to the diabetics (plasma insulin rose threefold), the rise in glucose production was still threefold greater than in the diabetic patients (p<0.02). We conclude that β-blockade is more effective in suppressing the hepatic response to adrenaline in diabetics than in normal subjects. Our data may explain why diabetic subjects are more vulnerable to hypoglycaemia during treatment with propranolol.