GLOMERULAR VOLUME AND THE GLOMERULAR VASCULAR POLE AREA IN PATIENTS WITH INSULIN-DEPENDENT DIABETES-MELLITUS

The vascular pole area (VPA) and glomerular volume were measured in re nal biopsies from 9 insulin-dependent diabetes mellitus (IDDM) patient s with normal albumin excretion rate (IDDM group 1), 38 IDDM patients with albumin excretion rate >15 mu g/min (IDDM group 2) and 10 living kidney donors (ND). The volume of individual glomeruli was estimated a s the sum of profile areas factored by the measured distance between l evels, t similar to 10 mu m, and VPA as the sum of chords multiplied b y t. Mean glomerular volume was increased in IDDM patients but reached statistical significance only in IDDM group 2 (P = 0.002 vs ND). VPA was significant ly different among the groups, mean (CV%) was 2036 (29 ) mu m(2) in ND, 3555 (34) mu m(2) in IDDM group 1, and 3528 (48) mu m (2) in IDDM group 2, p = 0.004 and 0.001, IDDM versus ND. VPA calculat ed as a percentage of the surface area of the corresponding glomerulus was 2.4 (23)% in ND, 3.4 (27)% in IDDM group 1, and 3.3 (32)% in IDDM group 2; P = 0.007 and 0.01, IDDM versus ND. The intra-biopsy coeffic ient of variation was high (20-35%) and of the same order in all group s for all three measurements. Glomerular volume and absolute as well a s relative size of VPA showed a positive correlation with estimates of mesangial expansion in IDDM group 2 and the VPA showed a negative cor relation with GFR. Thus, part of the enlargement may represent a compe nsatory phenomenon triggered by the development of structural and func tional abnormalities in the diabetic kidney.