Predictors of Microalbuminuria in Individuals with IDDM: Pittsburgh Epidemiology of Diabetes Complications Study

Abstract

OBJECTIVE To examine the relationships between microalbuminuria and the development of overt diabetic nephrology, elevated blood pressure, and a more atherogenic lipid profile; and to identify risk factors for the development of microalbuminuria in individuals with IDDM. Microalbuminuria has been associated with the subsequent development of overt diabetic nephropathy in individuals with IDDM. It is associated with elevated blood pressure and a more atherogenic lipid profile, but the temporal relationship between the development of microalbuminuria and the changes in these factors is unclear. RESEARCH DESIGN AND METHODS Baseline characteristics were examined in 256 individuals with IDDM who had normal albumin excretion (urinary AER ≤20 μg/min in ≥2 timed urine collections) and were re-examined 2 yr later. RESULTS At follow-up, 24 had developed microalbuminuria (AER 20–200 (Ag/min in ≥2 timed urine collections) and 1 had developed overt nephropathy (AER ≥200 μg/min). Overall, the significant independent predictors of microalbuminuria were HbA₁ (P < 0.001), low-density lipoprotein (P < 0.01), duration of IDDM (P < 0.05), and systolic blood pressure (P = 0.05). Sex-specific analyses showed HbA₁ age, and baseline AER were particularly important for men; whereas, for women, the main predictors were duration of IDDM and triglycerides. Duration-specific analyses showed that HbA₁ was an important predictor both for individuals with < and >20-yr duration. Low-density lipoprotein cholesterol was more important for subjects with shorter durations; whereas triglycerides were important for those with longer durations. CONCLUSIONS These results suggest that glycemic control, age or duration of IDDM, disturbed lipids, and possibly elevated blood pressure all may contribute to the development of microalbuminuria; and, further, that the adverse cardiovascular risk profile seen in individuals with overt nephropathy may begin to develop even before the detection of microalbuminuria.