[Sonographic changes in the size of the kidneys in type I diabetes as a method of early detection of diabetic nephropathy].

We carried out sonographic examination of 160 type I diabetics measuring the renal volume, the parenchyma/renal pelvis index and the brightness of the parenchyma. Creatinine and beta-2-microglobulin in the serum, creatinine clearance and albumin excretion by urine were determined as functional parameters. In contrast to existing results, we were unable to find significant changes in kidney size or function in newly diagnosed diabetics (duration of diabetes up to 6 months). Both the parenchyma/renal pelvis index and the kidney parenchyma were unchanged compared to control persons of the same age. It was only if diabetes lasted from 6 months to 5 years, that the renal volume was 19% larger (192 +/- 37 cm3/1.73 m2) than that of recently diagnosed patients (p less than 0.01). The index had increased by 15%, whereas the creatinine clearance had increased by 18% to 121 +/- 27 ml/min as a result of increased perfusion. The renal volume decreased continuously over a five-year period of duration of diabetes. Initially, microalbuminuria became manifest, followed some time later by a decrease in creatinine clearance and a corresponding increase in creatinine and beta-2-microglobulin in serum. No change in parenchyma brightness was noted. Diabetics with moderate renal insufficiency (creatinine 1.2 to 2 mg/dl) compared to diabetics without insufficiency developed larger kidneys (207 cm3/1.73 m2; p less than 0.01). Only in case of severe insufficiency (creatinine greater than 2 mg/dl) did the kidneys did shrink significantly (121 cm3/1,73 m2, n = 8, p less than 0.01). The temporary enlargement of the kidneys could be a prognostically unfavourable sign pointing towards a developing diabetic nephropathy.