[Hypoglycemia due to ophthalmic timolol in a diabetic]

In a 65-year-old man with insulin-dependent diabetes there was an increase in the severity and frequency of hypoglycemic attacks during treatment with ophthalmic timolol maleate for glaucoma. When timolol was stopped hypoglycemic attacks ceased. While recurrent exacerbation of hypoglycemia and its symptoms in insulin-dependent diabetics is a relatively common side-effect of systemic beta-blockers, there are scarcely any reports attributing this phenomenon to topical ophthalmic beta-blockers. Topical as well as systemic beta-blocking agents must be used with great caution in diabetics receiving insulin.