Urinary Excretion of Ceruloplasmin Is Elevated in the Subjects with "Borderline Glucose Tolerance Test"

Abstract

To examine whether or not there are any renal alterations in subjects with borderline glucose tolerance and in patients with non-insulin dependent diabetes mellitus (NIDDM) classified by the criteria of Japan Diabetic Association, urinary excretions of plasma proteins including albumin, ceruloplasmin (Cerulo) and IgG were measured in timed overnight urine samples. Eighty middle-aged, non-obese, normotensive, untreated men with urinary albumin excretion rates below 20 μg/minutes, β₂-microglobulin excretion rates below 140 μg/minutes and creatinine clearance values exceeding 80 ml·min⁻¹·(1.73 m²)⁻¹ were included in this study. Three groups were defined according to the results of 75 g oral glucose tolerance test (OGTT) as follows: D group, 10 subjects with NIDDM; B group, 40 subjects with “borderline glucose tolerance test” and N group, 30 subjects with normal glucose tolerance. The fractional clearance (Θ) of Cerulo, but not albumin and IgG, was elevated in 37.5% of the B group compared with the upper limit of that of the N group. Furthermore, Θ-Cerulo and Θ-IgG increased in the D group compared with those of the N and the B groups. Recently, we found that Θ-Cerulo and Θ-IgG increased in healthy volunteers when GFR was elevated by acute protein loading and that increase in Θ-Cerulo is remarkable than increase in Θ-IgG. The present result, taken together with our recent finding mentioned above, suggests that increases in Θ-Cerulo and Θ-IgG may not be due to an impairment of charge selectivity in the glomerular basement membrane, but due to an increase of intraglomerular hydraulic pressure.