In the years 1980-87, 19 cases of severe hypoglycaemia during treatment of Type 2 diabetes with glipizide were reported to the Swedish Adverse Drug Reactions Advisory Committee. Patient age was 75 +/- 9 years (mean +/- SD) (significantly higher than in all patients on glipizide in Sweden), and the duration of glipizide treatment ranged from 1 day to 4 years. Eleven patients presented with coma, three with reduced consciousness and five with other symptoms. An uneventful early recovery occurred in 14 patients. The remaining five patients had prolonged or recurrent hypoglycaemia for up to 60 h. Two of the patients, both with complicating disorders, died. In a case-control substudy, patients with glipizide-associated hypoglycaemia were found to have renal impairment more often than age- and sex-matched controls treated with glipizide (odds ratio 4.0). The median dose of glipizide (10 mg per day) was identical to that in controls. Other drugs, notably diuretics and benzodiazepines, were more commonly used by hypoglycaemic patients (median 5 vs 2 concomitant drugs, p less than 0.001). We conclude that the use of glipizide is associated with a risk of developing severe hypoglycaemia with a clinical course that is not always benign.