Objective: The drugs most commonly used to treat diabetes mellitus are sulfonylureas, biguanides and insulin. The most serious effects seen in overdose with these agents are hypoglycemia or lactic acidosis which may be fatal or cause cerebral defects. The present investigation analyzes inquiries made to a regional poisons unit involving overdoses with sulfonylureas, biguanides and insulin.
Patients and methods: A total of 218,070 made inquiries between 1995 and 2004 were evaluated. The inquiries were received by telephone and a standardized questionnaire was sent subsequently to the physicians calling for follow-up information. The cases were analyzed with regard to gender, age, etiology, symptoms and clinical outcome.
Results: 263 inquiries concerning sulfonylureas (48.3% female, 49.4% male, 2.3% sex unknown, average age 39.1 +/- 26.8 years), 172 concerning biguanides (60.5% female, 37.2% male, 2.3% sex unknown, average age 41.5 +/- 24.1 years), and 191 concerning insulin (53.9% female, 41.9% male, 4.2% sex unknown, average age 44.6 +/- 16.7) were made. In cases involving sulfonylureas, the etiology was deliberate self-poisoning in 62.7% and accidental in 31.9% (biguanides 60.5% and 29.1%, insulin 85.3% and 9.4%). Using the Poisoning Severity Score, no symptoms were observed in 41.4% of the patients with sulfonylurea overdose (biguanides 40.1%, insulin 22.5%), minor symptoms in 37.6% (biguanides 32.6%, insulin 33.5%), major symptoms in 14.4% (biguanides 13.4%, insulin 26.2%) and serious symptoms in 4.6% (biguanides 12.2%, insulin 14.7%). Returned questionnaires reporting clinical outcomes showed that a full recovery occurred in most patients (sulfonylureas 97.4%, biguanides 93.0%, insulin 94.4%), cerebral defects persisted in 1.8% of the cases involving sulfonylureas (biguanides 1.5%, insulin 2.4%), and that 0.9% of the patients with sulfonylurea overdose died (biguanides 6.1%, insulin 3.6%).
Conclusions: Sulfonylureas were the most frequently observed medication in cases of overdose with antidiabetic agents. Insulin overdose caused the highest number of major and serious symptoms. Overdose with biguanides led to the most deaths.