Table 1 Overview of classes and biopsy findings seen in glomerular lesions associated with diabetic kidney disease (DKD)

I

Thickening of glomerular basement membrane >430 nm in males ages 9 years and older, >395 nm in females ages 9 years and older

II

Mild to severe expansion of mesangial extracellular material: width of interspace exceeds two mesangial cell nuclei in two or more glomerular lobules; also known as “diffuse diabetic glomerulosclerosis”

III

Nodular sclerosis, Kimmelstiel-Wilson lesions: focal, lobular, mesangial lesions with acellular, hyaline/matrix core. Generally, these lesions indicate transition from early to later stages diabetic kidney disease

IV

More than 50% global glomerulosclerosis attributed to diabetes: fibrotic lesions with a build-up of extracellular matrix proteins in the mesangial space. Presence indicates advanced diabetic kidney disease

Other changes, lesions

Interstitial fibrosis and tubular atrophy; hyalinosis of the efferent, and possibly the afferent, arterioles; insudative lesions known as “capsular drop lesions” when found in Bowman’s capsule, as “hyalinized afferent and efferent arterioles when found in the afferent and efferent arterioles, and as fibrin cap lesions or hyalinosis when found in glomerular capillaries; “tip lesion” refers to abnormality in the tubuloglomerular junction, with atrophic tubules and no visible glomerular opening, and related to advanced DKD and macroalbuminuria