Renal function markers and metformin eligibility.

Area of Science:

• Endocrinology
• Nephrology
• Pharmacology

Background:

• Metformin is a primary treatment for type 2 diabetes mellitus (T2DM), improving insulin resistance and incretin secretion.
• Renal dysfunction is a key concern for metformin use due to lactic acidosis risk, historically assessed by serum creatinine.
• Modern renal function assessment uses formulas like CKD-EPI, incorporating age, gender, and race, and considers metformin safe down to eGFR of 30 mL/min/1.73 m2.

Purpose of the Study:

• To evaluate the impact of using serum creatinine alone versus estimated glomerular filtration rate (eGFR) on metformin prescription eligibility in T2DM patients.
• To analyze the characteristics of T2DM patients who would be excluded from metformin therapy based on creatinine levels alone.

Main Methods:

• Retrospective, observational, single-center study of T2DM patients on metformin with recent creatinine and eGFR measurements.
• Patients stratified into groups based on contraindication criteria: serum creatinine levels (women ≥1.4 mg/dL, men ≥1.5 mg/dL) and eGFR (<30 mL/min/1.73 m2).
• Comparison of demographic, comorbidity, and laboratory data between groups to assess the impact of each marker on metformin eligibility.

Main Results:

• Serum creatinine alone would contraindicate metformin in 12.4% of patients with eGFR > 30 mL/min/1.73 m2.
• Patients excluded by creatinine criteria had higher rates of male sex, longer diabetes duration, more target organ damage, and worse glycemic control.
• Using serum creatinine solely significantly reduced metformin eligibility (OR=0.88, 95% CI: 0.8-0.95, P=0.002).

Conclusions:

• Over-reliance on serum creatinine for renal function assessment leads to unnecessary metformin underprescription in T2DM.
• Employing more accurate eGFR assessments ensures patients receive optimal T2DM pharmacotherapy, including metformin.
• Revised criteria for metformin use based on eGFR are crucial for effective T2DM management.