(HealthDay News) — Use of estimated glomerular filtration rate (eGFR) rather than serum creatinine can expand metformin eligibility, according to a study published in Diabetes Care.

Delphine S. Tuot, MD, from the University of California in San Francisco, and colleagues examined the potential impact of recommendations to use eGFR rather than serum creatinine to determine metformin eligibility. 

Metformin eligibility was examined among 3902 adults with diabetes from the 1999 to 2010 National Health and Nutrition Examination Surveys using conventional serum creatinine thresholds and eGFR categories. Different eGFR equations were used to estimate creatinine clearance, including 4-variable Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine (CKD-EPIcr), and CKD-EPI cystatin C, as well as Cockcroft-Gault (CG).

The researchers found that MDRD eGFR of at least 45 mL/min/1.73 m² was most common for men and non-Hispanic blacks among adults with serum creatinine above conventional cut-offs (adjusted odds ratios, 33.3 vs women and 14.8 vs whites, respectively). An MDRD eGFR less 30 mL/min/1.73 m² was not seen among individuals with serum creatinine below conventional cut-offs. 

The population of individuals for whom metformin is likely safe was expanded with all estimating equations, ranging from 86 900 (CKD-EPIcr) to 834 800 (CG).

“The use of eGFR or [creatinine clearance] to determine metformin eligibility instead of [serum creatinine] can expand the adult population with diabetes for whom metformin is likely safe, particularly among non-Hispanic blacks and men,” the researchers wrote.


  1. Tuot DS, Lin F, Shlipak MG, et al; for the CDC CKD Surveillance Team. Potential Impact of Prescribing Metformin According to eGFR Rather Than Serum Creatinine. Diabetes Care. 2015;38(11):2059-2067.