[The renal tubulointerstitium in diabetes mellitus]

Recently, the tubulo-interstitial lesions in diabetes mellitus (DM) have become of greater interest, as well as, glomerulosclerosis. From the view points of tubular function, a variety of changes, including tubular proteinuria and transport of sodium, glucose, and divalent ions have been known until the present time, although the details remain to be elucidated. Morphologically the interstitial fibrosis and the thickening of tubular basement membrane were pointed out to be important features in incipient or overt diabetic nephropathy of insulin-dependent DM patients. We found the expansion of interstitium even in the area without hyalinized glomeruli and atrophic tubules in normo- and microalbuminuric non-insulin dependent DM patients by semiquantitative evaluation of biopsy specimens. Further studies of the mechanisms will be necessary to clarify the mechanism of the development of diabetic nephropathy.