Predicting Diabetic Nephropathy in Insulin-Dependent Patients

TLDR

The study examined whether microalbuminuria and baseline glomerular filtration rate, renal blood flow, and blood pressure predict later development of overt proteinuria in type I diabetic patients. Forty‑four type I diabetic patients with albumin excretion below 150 µg/min were followed from 1969–1976 and 43 were reassessed in 1983. Microalbuminuria at baseline predicted overt proteinuria, and higher initial GFR and blood pressure were associated with progression, whereas renal blood flow was not elevated; none of the patients with initial microalbuminuria below 15 µg/min developed clinically detectable proteinuria.

Abstract

We studied whether microalbuminuria (urinary albumin excretion rates of 15 to 150 micrograms per minute) would predict the development of increased proteinuria in Type I diabetes. We also studied the influence of glomerular filtration rate, renal blood flow, and blood pressure on the later development of proteinuria. Forty-four patients who had had Type I diabetes for at least seven years and who had albumin excretion rates below 150 micrograms per minute were studied from 1969 to 1976, and 43 were restudied in 1983. Of the 14 who initially had albumin excretion rates at or above 15 micrograms per minute, 12 had clinically detectable proteinuria (over 500 mg of protein per 24 hours) or an albumin excretion rate above 150 micrograms per minute at the later examination. Of the 29 who initially had albumin excretion rates below 15 micrograms per minute, none had clinically detectable proteinuria at the later examination, although four had microalbuminuria. Those whose condition progressed to clinically overt proteinuria had elevated glomerular filtration rates and higher blood pressures at the initial examination than did those in whom proteinuria did not develop. Renal blood flow was not elevated in these patients. We conclude that microalbuminuria predicts the development of diabetic nephropathy and that elevated glomerular filtration rates and increased blood pressure may also contribute to this progression.