GLOMERULAR HYPERFILTRATION IN YOUNG POLYNESIANS WITH TYPE-2 DIABETES

An increase in glomerular filtration rate (hyperfiltration) may be an important early event in the initiation of diabetic nephropathy but th e prevalence of hyperfiltration appears to vary between different popu lations with type 2 diabetes. We have measured glomerular filtration r ate using Cr-51 EDTA clearance in 15 young Polynesians (mean age 32 ye ars), 1-30 months after the initial diagnosis of type 2 diabetes and 1 5 control Polynesian subjects of comparable age and sex distribution. The mean glomerular filtration rate in the diabetic subjects (216 ml/m in) was 57% greater than that of the controls (137.5 ml/min, P < 0.000 1). About one-third of their excess in glomerular filtration rate coul d be accounted for by the marked obesity of the diabetic subjects, but even after correcting for body size the diabetic subjects still had a significantly higher mean glomerular filtration rate than controls (1 65.6 vs. 119.6 ml/min per 1.73 m(2), P < 0.001); 73% of the diabetic s ubjects had hyperfiltration (> 140 ml/min per 1.73 m(2)). The diabetic subjects were normotensive but nonetheless had increased rates of alb umin excretion (median 61 versus 9 mg/day, P < 0.001). We conclude tha t hyperfiltration is common in young Polynesians with recently diagnos ed type 2 diabetes. Prospective studies are needed to determine whethe r this early abnormality of renal function heralds the later developme nt of overt nephropathy.