Which glomerular changes are characteristic of diabetic nephropathy?

• A. Interstitial fibrosis and arteriolosclerosis
• B. Crescent formation
• C. Mesangial expansion with GBM thickening and nodular glomerulosclerosis
• D. Glomerular basement membrane split

Answer: (C)

The main concept here is the specific glomerular pattern produced by long-standing diabetes. Diabetic nephropathy classically causes mesangial expansion with thickening of the glomerular basement membrane, and it often progresses to nodular glomerulosclerosis (the Kimmelstiel-Wilson lesions). The thick GBM and expanded mesangium reduce filtration efficiency and set the stage for progressive proteinuria and renal dysfunction.

Why this answer fits best: the combination of mesangial expansion, GBM thickening, and nodular glomerulosclerosis is the hallmark glomerular lesion of diabetic nephropathy, reflecting chronic hyperglycemia and its effect on the glomerulus.

Interpreting the other options briefly: interstitial fibrosis and arteriolosclerosis can accompany chronic kidney disease but are not the defining glomerular changes of diabetic nephropathy; crescent formation points to a rapidly progressive glomerulonephritis rather than the diabetic pattern; glomerular basement membrane splitting is not typical of diabetes and is associated with other diseases like Alport syndrome or certain MPGN variants.