Risk factors for development of incipient and overt diabetic nephropathy in type 1 diabetic patients - A 10-year prospective observational study

OBJECTIVE - To evaluate prospectively putative risk factors for development of microalbuminuria and macroalbuminuria in type 1 diabetes. RESEARCH DESIGN AND METHODS - prospective observational study of a cohort of type 1 diabetic patients followed in the Outpatient clinic at Steno Diabetes Center for greater than or equal to10 years (median 9 years). We followed 537 patients aged greater than or equal to18 years With type 1 diabetes, With duration of diabetes greater than or equal to5 years, with normoalbuminuria (urinary albumin excretion rate : 30 mg/24 h). and who were not taking antihypertensive medication. Risk factors for development of microalbuminuria and macroatbuminuria were evaluated. RESULTS - The mean progression of urinary albumin excretion rate was 7.6% (SE 0.8) per year. During follow-up, 134 patients (25%) progressed to persistent microalbuminuria or macroalbuminuria (>30 mg/24 h in two of three consecutive urine samples). Cox multiple regression analysis using baseline values of putative predictors of progression showed the following significant predictors of progression from normoalbuminuria to microalbummuria or macroalbuminuria: baseline log urinary albumin excretion rate 2.63 (relative risks 95% Cl 1.65-4.19), HbA(1C) 1.13% (1.04-1.23), presence of any retinopathy 1.90 (1.26-2.88), and smoking 1.61 (1.11-2.33). Sex, duration of diabetes, arterial blood pressure, serum creatinine, height, and social class were not risk factors. CONCLUSIONS - Our study suggests that several Potentially modifiable risk factors predict the development of microalbuminuria and macroalbuminuria in type 1 diabetic patients.