Table 4.

Classification of glomerular lesions in diabetic kidney disease

Class	Description	Inclusion criteria
I	Mild or non-specific light microscopy changes and GBM thickening proved by electron microscopy	Biopsy does not meet any of the criteria for class II, III or IV GBM >395 nm in female and >430 nm in male subjects 9 years of age or older
IIa	Mild mesangial expansion	Mild mesangial expansion in 25% of the observed mesangium. Biopsy does not meet criteria for class III or IV
IIb	Severe mesangial expansion	Severe mesangial expansion in 25% of the observed mesangia. Biopsy does not meet criteria for class III or IV
III	Nodular sclerosis (Kimmelstiel–Wilson lesion)	At least one convincing Kimmesteil–Wilson lesion. Biopsy does not meet criteria for class IV
IV	Advanced diabetic glomerulosclerosis	Global glomerular sclerosis in >50% of glomeruli. Lesions from class I–III

GBM, glomerular basement membrane. Adapted from Tervaert et al. (2010).