Nodular thickening of peritubular basement membranes in diabetic kidneys.

A conspicious renal change associated with diabetes is the thickening of the basement membranes. This was generally considered diffuse and little attention was paid to its nodular character. In the present study of the nodules, their topo-optical reation, electron microscopic fine structure as well as their trypsin digestibility after periodic acid-sulphatation revealed their basement membrane character. The increased basophilia obtained by the aldehyde-bisulphite-toluidine blue reaction indicated an increased amount of sugar components, whereas the decreased double refraction and the red polarization colours a decrease of the micellary arrangement. The change is mostly observed in diabetics; the specific localization around the Henle loops may refer eventual hyperosmolar effects, whereas the nodular character points to the role of local factors.