The clinical course of renal function in NIDDM patients with normo- and microalbuminuria

Abstract

Objectives. To assess the clinical course of renal function in relation to risk factors in NIDDM patients with normo- and microalbuminuria. Design. Prospective clinical study. Setting. Outpatient diabetic clinic. Subjects. Thirty-two NIDDM patients with normo- or microalbuminuria followed for (mean (range)) 5.5 (3.3-7.5) years. Main outcome measures. Glomerular filtration rate, urinary albumin excretion rate, blood pressure, lipids, glycaemic control. Results. The mean rate of decline of glomerular filtration rate was -1.2±2.3 (mean ± SD) (95% confidence intervals: -2.0 - -0.3) mL min-1 1.73 m-2 year-1 (p = 0.009). A considerable interindividual variation was observed (range -6.7 to +3.4 mL min-1 1.73 m-2 year-1). No difference was found between normo- and microalbuminuric patients (-1.2±0.5 vs. -1.0±0.7 mL min-1 1.73 m-2 year-1) or between patients with and without antihypertensive treatment (-1.7±0.7 vs. -0.7±0.4 mL min-1 1.73 m-2 year-1). By multiple linear regression analysis the fall rate of glomerular filtration was determined by the mean glomerular filtration rate level (p = 0.036). Analysis of patients without antihypertensive treatment revealed that urinary albumin excretion rate and HbA(1c) levels significantly determined the fall rate of glomerular filtration (P < 0.001 and = 0.014). Conclusions. The average decline in renal function of these normo- and microalbuminuric NIDDM patients was not increased as compared to the age related fall rate of healthy subjects but varied markedly. Low glomerular filtration rate is associated with a higher fall rate. In patients without antihypertensive treatment higher urinary albumin excretion rate, and poorer glycaemic control are factors associated with an increased fall rate of glomerular filtration.