Table 2.

International pathologic classification of glomerular changes in diabetic kidney disease

Class	Description	Inclusion Criteria
1	Mild or nonspecific light microscopy changes and electron microscopy–proven GBM thickening	GBM>395 nm in women and >430 nm in men 9 yr of age and older; biopsy does not meet any of the criteria mentioned below for classes 2–4
2a	Mesangial expansion, mild	Mild mesangial expansion in >25% of the observed mesangium; biopsy does not meet criteria for class 3 or 4
2b	Mesangial expansion, severe	Severe mesangial expansion in >25% of the observed mesangium; biopsy does not meet criteria for class 3 or 4
3	Nodular sclerosis (Kimmelstiel–Wilson lesion)	At least one convincing Kimmelstiel–Wilson lesion; biopsy does not meet criteria for class 4
4	Advanced diabetic glomerulosclerosis	Global glomerular sclerosis in >50% of glomeruli; lesions from classes 1–3

Degree of mesangial expansion: mild mesangial expansion occupies an area smaller than the area of the capillary lumen. Severe mesangial expansion occupies an area greater than the area of the capillary lumen (33). GBM, glomerular basement membrane.