The earliest structural abnormality of the glomerulus detectable in diabetes mellitus, preceding the onset of measurable albuminuria, is:

• A Tubulointerstitial fibrosis and tubular atrophy
• B Formation of Kimmelstiel-Wilson nodules
• C Hyaline arteriolosclerosis of the afferent and efferent arterioles
• D Thickening of the glomerular basement membrane ✓

Explanation

Diffuse thickening of the GBM, visible only by electron microscopy, appears within a few years of diabetes onset and precedes microalbuminuria. Nonenzymatic glycosylation of matrix proteins drives this change. Nodular glomerulosclerosis, hyaline arteriolosclerosis, and interstitial scarring all represent later stages that accompany established proteinuria and declining filtration. The sequence tested here is GBM thickening first, then diffuse mesangial expansion, then nodular lesions with overt nephrotic-range proteinuria.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.