**Core Concept**
Diabetic nephropathy is a common complication of diabetes mellitus, characterized by progressive renal damage and loss of kidney function. Early diabetic nephropathy manifests with microalbuminuria, which is the presence of small amounts of albumin in the urine. The recommended treatment aims to slow the progression of renal damage and delay the onset of clinical proteinuria.

**Why the Correct Answer is Right**
The recommended treatment for early diabetic nephropathy involves tight control of blood glucose levels, blood pressure management, and the use of renin-angiotensin-aldosterone system (RAAS) inhibitors. Tight glucose control helps to reduce the metabolic stress on the kidneys, while blood pressure management helps to reduce proteinuria and slow the progression of renal damage. RAAS inhibitors, such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), help to reduce intraglomerular pressure and slow the progression of renal damage.

**Why Each Wrong Option is Incorrect**
**Option A:** Insulin therapy alone may not be sufficient to control blood glucose levels and slow the progression of renal damage.
**Option B:** Beta-blockers may not have a significant impact on reducing proteinuria and slowing the progression of renal damage.
**Option C:** Corticosteroids are not typically used in the treatment of diabetic nephropathy, as they may worsen proteinuria and renal function.

**Clinical Pearl / High-Yield Fact**
RAAS inhibitors are the cornerstone of treatment for early diabetic nephropathy, as they have been shown to slow the progression of renal damage and delay the onset of clinical proteinuria.

**Correct Answer: C. Corticosteroids are not typically used in the treatment of diabetic nephropathy, as they may worsen proteinuria and renal function.**