Relationship of renal size to nephropathy in type 1 (insulin-dependent) diabetes.

Thirty-five patients with Type 1 (insulin-dependent) diabetes mellitus and 90 normal subjects had renal size (renal area index) determined by X-ray and also had examination of renal biopsies by light and electron microscopy. Renal area index of 206 +/- 32 cm2/1.73 m2 (mean +/- SD) in the Type 1 diabetic patients exceeded that in the normal subjects (180 +/- 25 cm2/1.73 m2, p less than 0.001). In the diabetic patients, the renal area index correlated with creatinine clearance (r = +0.43, p less than 0.05), but did not correlate with urinary albumin excretion, or the electron microscopic measurements of percentage total mesangium and glomerular basement membrane width. In diabetic patients with clinical nephropathy or severe glomerulopathy on biopsy, the kidneys may remain large. Thus, renal size does not indicate the severity of diabetic renal lesions on biopsy.