The clinical course of diabetic nephropathy may be described in stages
; the normo-, micro- and macroalbuminuric stage. The basis for its dev
elopment is the diabetic glomerulopathy in which accumulation of basem
ent membrane (BM) material is pivotal. Normoalbuminuric patients have
normal or slightly increased BM thickness; microalbuminuric patients s
how further BM thickening and mesangial expansion, formation of new ca
pillaries, arteriolar and interstitial changes. The degree of diabetic
glomerulopathy may be predicted by long-term glycemic control, diabet
es duration and glomerular filtration rate (GFR). A slight decline in
GFR in microalbuminuric patients is associated with increases in BM th
ickness, capillary diameter and interstitial volume fraction. In turn,
the degree of early diabetic glomerulopathy may predict the level of
microalbuminuria several years later. Improved metabolic control, even
to not normal levels, retards the increase of BM thickness and matrix
volume in microalbuminuric adolescents. If matrix accumulation may be
prevented diabetic nephropathy will not develop. Morphometric analyse
s may thus be useful in evaluating the effect of intervention, also du
ring shorter periods and at early stages.