Predictors of mortality and end-stage diabetic complications in patients with Type 1 diabetes mellitus on intensified insulin therapy

Aims To assess predictors of mortality and end-stage diabetic complications in patients with Type 1 diabetes mellitus on intensified insulin therapy. Methods A cohort of 3674 patients (insulin treatment before age 31) who had participated in a 5-day in-patient group treatment and teaching programme for intensification of insulin therapy between 9/1978 and 12/1994 were re-assessed after 10 +/- 3 (mean +/- SD) years. Results Vital status and data on blindness, amputations, and renal replacement therapy were documented for 97% patients; 7% patients had died, 1.3% had become blind, 2% had amputations and 4.6% started renal replacement therapy. Using the Cox proportional hazards model, the following risk factors of mortality as assessed at baseline were identified: nephropathy (at least macroproteinuria), hazard ratio 3.8 (95% confidence interval 2.6-5.6); smoking, 1.9 (1.4-2.6); diabetes duration, 1.5 (1.2-1.8) for a difference of 10 years; serum cholesterol, 1.1 (1.0-1.2) for a difference of 1 mmol/l; lower social status, 1.4 (1.1-1.8) for a difference of 1 out of 3 levels; age, 1.3 (1.1-1.6) for a difference of 10 years; male sex, 1.4 (1.1-1.9); systolic blood pressure, 1.1 (1-1.2) for a difference of 10 mmHg. For the combined endpoint - blindness or amputations or renal replacement therapy - predictors were: nephropathy, foot complications, HbA(1c), smoking, cholesterol, systolic blood pressure, retinopathy, hypertension, and social status. Conclusion In Type 1 diabetic patients who start intensified insulin therapy, nephropathy remains the strongest predictor of mortality and end-stage complications. Glycosylated haemoglobin is a risk factor of end-stage complications but not of mortality. Conventional risk factors comparable to the general population, particularly smoking become operative as predictors of both mortality and end-stage complications.