In a population-based study, the social situation of 91 young adult patients with Type 1 diabetes mellitus (IDDM) since childhood was compared to that of an age- and sex-matched group of 189 healthy persons. Their mean age was 37.2 years, duration of diabetes 28.7 years and severe complications were present in 13 of the 91 patients. A nearly 10-fold increased mortality rate was found in diabetic patients, mainly due to diabetic nephropathy and trauma, including suicide. The employment rate was lower in diabetic patients (71% vs 85%, p < 0.05); the need for welfare benefits was greater (15% vs 3%, p < 0.01). These differences were mainly the consequence of diabetic late complications. Education, housing conditions, life style, civil state, alcohol and smoking habits were similar in both groups. Confidence in the future was slightly less in diabetic patients (p < 0.05). In conclusion, besides an increased mortality rate, the present study has shown no serious social consequences in adult Type 1 diabetic patients without severe late complications, as compared to matched controls. Our results indicate that IDDM affects social life only to a limited extent, in the absence of severe vascular complications.