The most common cause of chronic kidney disease (CKD) in the United States is diabetes mellitus. Chronic hyperglycemia in diabetes leads to diabetic nephropathy, characterized by glomerular basement membrane thickening, mesangial expansion, and eventual glomerulosclerosis. This progressive damage reduces kidney function over time, making diabetes the leading contributor to CKD and end-stage renal disease. Early detection and glycemic control are crucial to slowing CKD progression in diabetic patients.

Reference: Harrison's Principles of Internal Medicine, J. Larry Jameson, 20th Edition.