A 64-year-old woman with type 2 diabetes for 10 years now develops increasing fatigue, dyspnea, and pedal edema. On examination, her blood pressure is 165/90 mmHg, pulse 90/min, JVP is 4 cm, heart sounds are normal, lungs are clear, and there is 3+ pedal edema.Her urinalysis is positive for 3 gm/L of protein and no casts or red blood cells. An abdominal ultrasound reveals normal size kidneys and no hydronephrosis. Which of the following renal diseases is the most likely diagnosis in this patient?

**Core Concept**
Diabetic nephropathy is a leading cause of chronic kidney disease and end-stage renal disease worldwide, often presenting with proteinuria, hypertension, and renal insufficiency. The pathophysiology involves hyperglycemia-induced damage to the glomerular basement membrane and mesangial expansion.

**Why the Correct Answer is Right**
The patient's long-standing type 2 diabetes, proteinuria, and hypertension are classic findings for diabetic nephropathy. The absence of hematuria and normal-sized kidneys on ultrasound further support this diagnosis. Diabetic nephropathy typically progresses to renal insufficiency over years, which is consistent with the patient's symptoms of fatigue and pedal edema.

**Why Each Wrong Option is Incorrect**
**Option A:** Focal segmental glomerulosclerosis (FSGS) is a cause of nephrotic syndrome, but it is less likely in this patient with long-standing diabetes. FSGS often presents with more severe proteinuria and a more rapid decline in kidney function.
**Option B:** Membranous nephropathy is a cause of nephrotic syndrome, but it is more common in adults without a history of diabetes. This patient's long-standing diabetes makes diabetic nephropathy a more likely diagnosis.
**Option C:** Rapidly progressive glomerulonephritis (RPGN) is a cause of acute kidney injury, but it typically presents with hematuria, proteinuria, and a rapid decline in kidney function. This patient's presentation is more consistent with chronic kidney disease.
**Option D:** Minimal change disease is a cause of nephrotic syndrome, but it is more common in children and often presents with more severe proteinuria and a more rapid response to corticosteroid therapy.

**Clinical Pearl / High-Yield Fact**
Diabetic nephropathy is the leading cause of end-stage renal disease worldwide, and early detection and management are crucial to prevent progression. Regular monitoring of urine protein-to-creatinine ratio and serum creatinine levels is essential in patients with diabetes.

**Correct Answer:** C. Diabetic nephropathy.

✓ Correct Answer: C. glomerulosclerosis with mesangial thickening