Microalbuminuria and pulse pressure are powerful predictors of 25-year mortality in type 1 diabetes

The very long-term prognostic significance of microalbuminuria and blood pressure variables for mortality in type 1 diabetes is not clarified. In 1977, 272 patients were identified through outpatients’ clinics and GP’s. The cohort constituted a representative sample of adult type 1 diabetic patients in Aarhus County. Inclusion criteria were age ≥15 years (mean 34±12.8) and duration of diabetes ≥ 5 years (mean 18±10.5). Urinary albumin concentration, blood pressure, macrovascular disease, retinopathy, glycemic control, s-creatinine, s-cholesterol, and smoking habits were determined. Three patients were lost to follow-up. All-cause mortality was 37% (99/269) over 25 years for the whole group. As indicated in the table, baseline BP and pulse pressure increased significantly with increasing albuminuria levels as did mortality over 25 y. Cox multiple regression analysis (age-stratified) identified the following significant independent predictors of all cause mortality: microalbuminuria (RR 2.8; 95% CI [1.5-5.2]), duration of diabetes (1.6 pr 10 y [1.1-2.3]), macrovascular disease at baseline (1.9; [1.1-3.79]), smoking (1.9; [1.1-3.3]), glycemic control (2.3; [1.1-4.7]), and pulse pressure (2.8; [1.3-6.3]). Systolic, diastolic and mean BP was excluded from the model as was gender, s-cholesterol, s-creatinine and retinopathy. Mortality in patients with UAC 20-200 mg/l was significantly increased compared with patients with UAC <20 mg/l (p<0.001) and similar in patients with short (<16 y) and long (>16 y) duration (p=0.9, age-corrected). For comparison, age, sex, and calendar year specific mortality rates were obtained from the Danish Institute of Epidemiology. The relative risk (RR) for total mortality was significantly increased in the diabetic patients vs the background population (table).