Renal functional reserve in patients with Type 1 diabetes mellitus.

ABSTRACT

AIM: Decreased renal functional reserve might precede incipient diabetic nephropathy in patients with Type 1 diabetes. The aim of this study was to assess the relationship between renal functional reserve and easily assessable estimates of systemic endothelial dysfunction in normoalbuminuric patients with Type 1 diabetes and diabetic retinopathy. METHODS: Renal functional reserve was calculated as the relative change in glomerular filtration rate after protein ingestion. Glomerular filtration rate was measured using pharmacokinetic compartmental analysis of single-shot plasma sinistrin clearance. We measured the activity of von Willebrand factor and concentrations of C-reactive protein and apolipoprotein B, as easily assessable estimates of systemic endothelial dysfunction. RESULTS: Twenty-two patients were studied. Renal functional reserve was inversely associated with activity of von Willebrand factor (R=-0.431, p=0.045) and, in a multivariate model, with concentration of C-reactive protein (R=0.652, p=0.031). CONCLUSION: Renal functional reserve is inversely associated with concentration of C-reactive protein in normoalbuminuric patients with Type 1 diabetes and diabetic retinopathy. This finding provides evidence that decreased renal functional reserve might reflect endothelial dysfunction. We speculate that decreased renal functional reserve might possibly show as an early marker of diabetic nephropathy.