Urinary albumin excretion in patients with non-insulin-dependent diabetes mellitus in an early microalbuminuric stage.

We investigated the urinary albumin excretion and renal hemodynamics of normotensive nonobese patients with impaired glucose tolerance (IGT) and non-insulin-dependent diabetes mellitus (NIDDM) in an early microalbuminuric stage (defined by albuminuria less than 30 mg/day). In comparison with normal subjects, a significant increase in urinary albumin excretion was observed already in the IGT stage [U-albumin/U-creatinine: NL (20 subjects), 5.3 +/- 1.7 mg/g Cr; IGT (23 subjects), 11.9 +/- 6.7 mg/g Cr; DM (20 subjects), 12.8 +/- 5.7 mg/g Cr]. A 3-week diet therapy combined with physical exercise prescribed for 53 normotensive non-obese mild NIDDM patients resulted in improvement in glucose tolerance, concomitant with lowered systemic blood pressure and a decrease in urinary albumin excretion (SBP: 128.4 +/- 13.0 to 106.4 +/- 10.2 mm Hg, p less than 0.01; DBP: 78.2 +/- 10.8 to 66.0 +/- 8.0 mm Hg, p less than 0.01; U-albumin: 19.4 +/- 10.3 to 10.1 +/- 9.1 mg/day, p less than 0.01). However, glomerular filtration rate, renal plasma flow, filtration fraction and urinary beta 2-microglobulin excretion remained unchanged. From these results, we hypothesized that focal glomerular hyperperfusion increases urinary albumin excretion in patients with early NIDDM.