COURSE OF RENAL-DISEASE IN PIMA-INDIANS WITH NON-INSULIN-DEPENDENT DIABETES-MELLITUS

The course of renal disease attributable to non-insulin-dependent diab etes mellitus (NIDDM) has been characterized extensively in the Pima I ndians of Arizona. Studies in this population indicate that the glomer ular filtration rate often increases at the onset of NIDDM and remains elevated as long as normal urinary albumin excretion (< 30 mg albumin /g creatinine) or microalbuminuria (30-299 mg albumin/g creatinine) pe rsist. After the development of macroalbuminuria (greater than or equa l to 300 mg albumin/g creatinine), the glomerular filtration rate decl ines at least as rapidly as reported in subjects with insulin-dependen t diabetes. Morphologic examination of kidney tissue reveals extensive glomerular sclerosis, mesangial expansion, and widening of epithelial cell fool processes and the glomerular basement membrane in the subje cts with macroalbuminuria, but not in those with normo-or microalbumin uria. These findings suggest that substantial structural damage to the kidney occurs al or about the time that macroalbuminuria develops, an d the decline in glomerular function in those with macroalbuminuria is due to a loss of ultrafiltration surface area and a reduction in glom erular hydraulic permeability.