In a woman in her 60s with long‑standing diabetes mellitus and hypertension, treated with insulin and valsartan (angiotensin II receptor blocker), presenting with lower‑limb edema and normal‑sized kidneys on imaging, what is the most likely diagnosis?

Diabetic Nephropathy

In a woman in her 60s with long-standing diabetes and hypertension presenting with lower-limb edema and normal-sized kidneys on imaging, the diagnosis is diabetic nephropathy (Option A). 1, 2

Clinical Reasoning

The combination of established diabetes, hypertension, and lower-limb edema (suggesting proteinuria and volume overload) creates the classic triad of diabetic nephropathy. 1 The American Diabetes Association confirms that established diabetes with proteinuria is the hallmark presentation of diabetic nephropathy, where hypertension both contributes to and results from the underlying kidney disease. 1

Normal kidney size on imaging does not exclude diabetic nephropathy. 1 This is a critical clinical pearl—diabetic nephropathy characteristically presents with normal or even enlarged kidneys in early-to-moderate stages, unlike chronic glomerulonephritis which typically shows small, shrunken kidneys. 1

Why Other Options Are Less Likely

Hypertensive Nephrosclerosis (Option D)

Hypertensive nephrosclerosis is unlikely because it typically presents with bland urinary sediment and minimal proteinuria, whereas diabetic nephropathy is characterized by significant proteinuria (often progressing from microalbuminuria ≥30 mg/g to macroalbuminuria ≥300 mg/g). 1 The patient's presentation with edema strongly suggests substantial proteinuria, making diabetic nephropathy far more probable. 2

Chronic Glomerulonephritis (Option C)

Chronic glomerulonephritis is less probable given the normal kidney size on imaging, which is not typical of chronic glomerulonephritis where kidneys are usually small and scarred. 1 Additionally, the clinical context of long-standing diabetes makes diabetic nephropathy the more parsimonious diagnosis. 2

Autosomal Dominant Polycystic Kidney Disease (Option B)

ADPKD would present with bilaterally enlarged kidneys with multiple cysts on imaging, not normal-sized kidneys, making this diagnosis incompatible with the imaging findings. 1

Clinical Implications and Management

The patient is already appropriately on valsartan (an ARB), which is specifically indicated for diabetic nephropathy with proteinuria in patients with type 2 diabetes and hypertension. 2 The American Diabetes Association recommends continuing ARB therapy for diabetic nephropathy with elevated serum creatinine and proteinuria. 2

Key management priorities include:

• Optimize blood pressure control to <130/80 mmHg to slow nephropathy progression. 1, 2

• Intensify glycemic control toward HbA1c <7%, as suboptimal control accelerates diabetic nephropathy progression. 2

• Quantify proteinuria with spot urine protein-to-creatinine ratio or 24-hour urine collection to establish baseline and monitor treatment response. 1

• Monitor for up to 20-30% increase in serum creatinine after optimizing RAS blockade, which reflects beneficial hemodynamic changes from reduced intraglomerular pressure rather than kidney damage. 1

• Consider nephrology referral if eGFR <60 mL/min/1.73 m² for specialized management. 2

Higher doses of valsartan (320-640 mg) have been shown to reduce albuminuria more effectively than the standard 160 mg dose in type 2 diabetes, apparently independent of blood pressure effects. 3