Potentiation of the hypoglycaemic response to glipizide in diabetic patients by histamine H2‐receptor antagonists

In a randomised placebo controlled study, two groups of six maturity onset diabetic patients stabilised on glipizide were given cimetidine (400 mg) or ranitidine (150 mg) 3 h before a standardised meal. In comparison with placebo, both cimetidine and ranitidine significantly reduced the post‐prandial rise in blood glucose by a mean of 40% and 25% respectively producing glucose levels of less than 3 mmol l‐1 (lowest 1.5 mmol l‐1) in four patients. Both drugs also significantly increased plasma glipizide AUC by approximately 20%. Caution should be exercised when initiating treatment with H2‐receptor antagonists in diabetics receiving sulphonylurea hypoglycaemic agents.