Glucagon in solution with a surfactant (deoxycholic acid 1% w/v) was administered by intranasal spray to 6 healthy fasting subjects and 6 insulin-dependent diabetics with insulin-induced hypoglycaemia. In the normal subjects, intranasal glucagon increased plasma glucose levels, with a dose-response effect. In the diabetic patients, plasma glucose levels showed a mean increase of 100% above nadir values in approximately 26 min in response to 7.5 mg intranasal glucagon; hypoglycaemic symptoms were relieved within about 7 min. These results suggest that intranasal glucagon is effective and may represent an alternative to parenteral glucagon or glucose or to oral sugar as the first-line treatment of hypoglycaemic episodes in insulin-dependent diabetics.