Tubular basement membrane thickening in diabetes mellitus.

Authors measured the thickness of the basement membranes of the proximal and distal tubuli in the renal cortex in 20 patients with verified diabetes mellitus. The test group consisted of 20 patients with small abnormalities of glomeruli (or in the range of variable norm), of the same sex and comparable age. Measurements were performed in locations without tubulo-interstitial changes. The average thickness of TBM in patients with diabetes mellitus was 1540 +/- 616 nm, and in the test group 360 +/- 86 nm, which is a statistically significant difference (p < 0.000000). In spite of the small number of cases and possible error in the manual measurement of electron microscopic pictures, a significant thickening of TBM in diabetes mellitus has been found. We consider this to be of diagnostic value.