Diabetes: Metformin Effectiveness in African Americans May Be Greater Than In Whites

L. Keoki Williams, MD, MPH Center for Health Policy and Health Services Research Department of Internal Medicine Henry Ford Health System Detroit, Michigan 48104MedicalResearch.com Interview with
L. Keoki Williams, MD, MPH
Center for Health Policy and Health Services Research
Department of Internal Medicine
Henry Ford Health System
Detroit, Michigan 48104

MedicalResearch: What are the main findings of the study?

Dr. Williams: Metformin is recommended as first line treatment for type 2 diabetes, and these recommendations are based on the results of clinical trials performed almost exclusively in white individuals.  This is the first study to specifically assess whether metformin is effective at reducing blood glucose levels in African American individuals.  In our large study of over 19,000 individuals, we showed that metformin was consistently more effective at reducing glycated hemoglobin (HbA1c) levels (a measure of long-term blood glucose control) in African Americans when compared with white individuals.


MedicalResearch: Were any of the findings unexpected?

Dr. Williams: We were surprised by the consistency of our findings.  Regardless of how well controlled (or uncontrolled) diabetes was at baseline, African American patients appeared to respond consistently better to metformin than did white patients.  In addition, the magnitude of the difference was also surprising (on the order of 0.5%), which is quite large when one considers that the average baseline HbA1c level was 7.5% in our study population and that being “controlled” on treatment is defined as a HbA1c level less than 7.0%.  Therefore, the difference in treatment response was well within the range of influencing whether patients achieved diabetes “control.

MedicalResearch: What should clinicians and patients take away from your report?

Dr. Williams: Although our study was based on observational data, the consistency of our findings support the current guidelines regarding metformin’s use.  Namely, as metformin appears to be effective (if not more effective) in African American individuals, it should also be considered the first line treatment for type 2 diabetes in this group, as well.  However, further studies are needed to assess whether the greater reduction in HbA1c levels in African Americans also translates to greater improvement in hard clinical outcomes, such as microvascular (e.g., retinopathy and nephropathy) and macrovascular (e.g., myocardial infarction and peripheral vascular disease) events.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Dr. Williams: This work highlights the importance of assessing medication response in all race-ethnic groups, as groups may have different rates of treatment-related benefits and harms.  Therefore, important next steps would be to assess metformin response in other population groups, as well as to replicate our findings in other African American individuals with type 2 diabetes.  Additional areas for future research include identifying the genetic factors that influence metformin response.  If these genetic determinants are present in multiple race-ethnic groups, they may occur at different frequencies, thereby manifesting as treatment response differences.

Citation:

Differing Effects of Metformin on Glycemic Control by Race-ethnicity

L. Keoki Williams, Badri Padhukasahasram, Brian K. Ahmedani, Edward L. Peterson, Karen E. Wells, Esteban González Burchard, and David E. Lanfear

DOI: http://dx.doi.org/10.1210/jc.2014-1539
Accepted: May 08, 2014

Published Online: June 12, 2014