Diabetic nephropathy

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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.

Histopathology of Diabetic Nephropathy

⭐ 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).

KDIGO 2012 CKD Prognosis by GFR and Albuminuria

⭐ 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.

Practice Questions: Diabetic nephropathy

Test your understanding with these related questions

A 52-year-old man comes to the physician for a routine health maintenance examination. He feels well. His blood pressure is 125/70 mm Hg. His glomerular filtration rate is calculated to be 105 mL/min/1.73 m2 and glucose clearance is calculated to be 103 mL/min. This patient is most likely being treated with which of the following agents?

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Flashcards: Diabetic nephropathy

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What is the most common nephropathy worldwide? _____

TAP TO REVEAL ANSWER

What is the most common nephropathy worldwide? _____

IgA nephropathy (Berger disease)

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