Metformin controls blood sugar more effectively in African Americans: Study

Dr Williams

African Americans taking metformin saw greater improvements in their blood sugar control than white patients who were prescribed the same medication, according to a study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism (JCEM).

“Metformin is recommended as the first line treatment for type 2 diabetes,” said one of the study’s authors, L. Keoki Williams, MD, MPH, of Henry Ford Health System in Detroit. “However, this is the first study to specifically assess whether metformin is effective at reducing blood glucose levels in African American individuals.”

In an observational study, Dr Williams and colleagues used pharmacy claims data and electronic medical records (EMR) data from Henry Ford Health System to examine blood sugar control in more than 19,000 individuals with diabetes who were prescribed metformin between January 1, 1997 and June 2, 2013. Among the participants, 7,429 were African American and 8,783 were white. Using pharmacy records, the researchers estimated each individual’s exposure to metformin and other diabetes medications. Each study participant had at least 2 hemoglobin A_1C (HbA_1C) blood sugar measurements taken at least 4 months apart while they were on metformin.

“Because our exposure measures included the frequency of patient refills they at least in part accounted for patient adherence,” Dr Williams said.  “We also used data from the EMR to accounted for patient age, sex, size [body mass index], level of diabetes control at baseline, and use of other medications.” 

Because the HbA_1C test measures a person’s average blood sugar level from the past 3 months, researchers ran an analysis to measure the change in participants’ blood sugar levels in relation to the amount of metformin taken. The study found the maximum dose of metformin was associated with an absolute decrease in HbA_1C values of 0.9% among African Americans, according to a press release. In contrast, the same analysis found a 0.42% reduction in HbA_1C numbers among whites.

“We showed that metformin was consistently more effective at reducing glycated hemoglobin [HbA_1C] levels-a measure of long-term blood glucose control-in African Americans when compared with white individuals,” Dr Williams said.

“This study provides evidence that supports current diabetes management guidelines,” he said. “Namely, from our findings, it appears that metformin should be used as the first line treatment for type 2 diabetes in African Americans, as well as in white individuals. However, further studies are needed to assess whether the greater reduction in HbA_1C levels in African Americans also translates to greater improvement in hard clinical outcomes, such as kidney disease, eye disease, heart attacks, and circulatory problems, which would provide additional evidence to support using metformin as the initial treatment of choice for African American individuals with type 2 diabetes.”

Approximately 29 million Americans have diabetes. African Americans are twice as likely to be diagnosed with diabetes as whites and have a higher rate of complications such as kidney failure, according to the US Department of Health and Human Services’ Office of Minority Health.