THIN GLOMERULAR-BASEMENT-MEMBRANE IN DIABETIC-PATIENTS WITH URINARY ABNORMALITIES

To clarify the clinical and pathological significance of thin glomerul ar basement membranes (Thin-GBM) appearing in evident diabetics, we ex amined the renal biopsies from 179 diabetes mellitus (DM) patients wit h urinary abnormalities in which the number of non insulin dependent d iabetes mellitus cases was 140 cases while the remaining 39 cases had insulin dependent diabetes mellitus. In addition, 17 of these cases we re found to have either segmental or diffuse Thin-GBM by electron micr oscopy. The clinical and morphological parameters between the diabetic s with Thin-GBM (DM-Thin-GBM) and the diabetics without Thin-GBM (the controls) were significantly different regarding DM duration (DM-Thin- GBM vs control: 5.3 +/- 5.5 vs 9.8 +/- 6.5 years, p <0.01), Ccr (67.0 +/- 25.5 ml/min vs 45.6 +/- 24.4 ml/min, p <0.01), the incidence of he maturia (52.9% vs 24.5%, p <0.05) and hypertension (13.3% vs 51.3%, p <0.05). The severity of glomerular damage was mild in the DM-Thin-GBM group as compared to the control. The renal survival rate from the ons et of urinary abnormalities was higher in the DM-Thin-GBM group than i n the control (p <0.01). In the case of DM-Thin-GBM, the grade of prot einuria correlated with the mean width of the thickened GBM (p <0.01) and the spread of the thickened GBM which was more than 500 nm in widt h (p <0.001). The severity of microscopic hematuria correlated with th e spread of the Thin-GBM (p <0.05). The mean GBM thickness, the fracti onal volume of the mesangial matrix/glomerulus and the spread of the t hickened GBM weakly correlated with the DM duration, however the sprea d of the Thin-GBM was considered to be independent of either DM durati on or proteinuria. The above findings thus suggest that the Thin-GBM a ppearing in diabetics is a congenital GBM. malformation and that such Thin-GBM changes very little during the course of the disease, however , it may sometimes cause unexpected urinary abnormalities including he maturia.