Diabetic nephropathy

Pathophysiology - The Sugar Siege

• Chronic hyperglycemia drives glomerular damage via two main pathways:
  • Non-enzymatic Glycation: Glucose binds to proteins, forming Advanced Glycation End-products (AGEs).
  • PKC Activation: Hyperglycemia activates the Protein Kinase C (PKC) pathway.
• These pathways trigger a cascade leading to structural and functional kidney changes.

⭐ The earliest detectable change in diabetic nephropathy is glomerular hyperfiltration, where the GFR is paradoxically increased.

Diagnosis & Staging - Finding the Leaks

• Annual Screening:
  • Type 2 DM: Start at diagnosis.
  • Type 1 DM: Start 5 years post-diagnosis.
• Primary Test: Urine Albumin-to-Creatinine Ratio (UACR) from a spot sample.
  • Confirm with 2 positive tests over 3-6 months.
• Staging Albuminuria (UACR):
  • A1 (Normal): < 30 mg/g
  • A2 (Microalbuminuria): 30-300 mg/g
  • A3 (Macroalbuminuria): > 300 mg/g
• Monitor eGFR: Track decline to stage CKD (G1-G5).

⭐ Diabetic retinopathy is strongly associated with nephropathy; its presence supports the diagnosis, while its absence in a proteinuric T1DM patient may suggest another cause.

Management - The Damage Control Plan

• Primary Goals:

  • Glycemic Control: Target HbA1c ~7%.
  • BP Control: Target <130/80 mmHg.
  • RAAS Blockade: For albuminuria (UACR >30 mg/g).
    • • Start ACE Inhibitor (-pril) or ARB (-sartan).
    • • ⚠️ Monitor for hyperkalemia.

• Cardio-Renal Protection:

  • SGLT-2 Inhibitors (-gliflozin): Standard of care for CKD with albuminuria. Reduces intraglomerular pressure.
  • Finerenone: Non-steroidal MRA; reduces fibrosis and inflammation.

⭐ SGLT-2 inhibitors slow eGFR decline and reduce risk of cardiovascular events, benefits that are independent of their glucose-lowering effects.

High‑Yield Points - ⚡ Biggest Takeaways

• Diabetic nephropathy is the leading cause of end-stage renal disease (ESRD) in the United States.
• The earliest clinical sign is microalbuminuria; screen annually with a urine albumin-to-creatinine ratio (UACR).
• ACE inhibitors or ARBs are the first-line treatment to slow disease progression, even in normotensive patients.
• Kimmelstiel-Wilson lesions (nodular glomerulosclerosis) are pathognomonic histological findings.
• Strict glycemic control (target HbA1c < 7%) and aggressive blood pressure control (< 130/80 mmHg) are paramount.