Type 2 Diabetes Subtypes and Risks Related to Race, Ethnicity

Anne L. Peters, MD


March 03, 2021

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This transcript has been edited for clarity.

A topic that has always interested me is the notion that there is more than one type of type 2 diabetes. Throughout my career, I've seen patients from all walks of life and places all around the world — and I think there must be a thousand different subtypes of diabetes.

I know that I can't always pinpoint why a person has one kind of diabetes or another, but I've certainly been aware that there seem to be different clusterings of types of diabetes. If I were smarter, I could figure out what that all means and how to determine what subtype of diabetes a patient has or does not have.

There was a recent article published in the Journal of Clinical Endocrinology & Metabolism, written by Michael Bancks from Wake Forest School of Medicine and his colleagues, titled "Association of Diabetes Subgroups With Race/Ethnicity, Risk Factor Burden, and Complications: The MASALA and MESA Studies." They start out from the premise that I just discussed — that we know that there are differences in rates of diabetes complications and outcomes as well as disparities, and that many factors can lead to this. However, the specific role of race and ethnicity is not well characterized. Although we have some ideas about it, it's certainly an area that we need to understand better.

The authors took data from two trials: MASALA and MESA. MASALA stands for "Mediators of Atherosclerosis in South Asians Living in America." This was done at two sites in San Francisco and Chicago and included 906 individuals. The MESA study is the Multi-Ethnic Study of Atherosclerosis in people who have diabetes. Their sample size was bigger (6814 people), included four ethnic groups (non-Hispanic White persons, African American persons, Hispanic persons, and Chinese American persons) and was done in six different communities. No one in either group had baseline diagnosable cardiovascular disease.

This analysis included 1293 participants from both cohorts. In addition to having subgroups based on ethnicity and race, they also had five different diabetes subgroups: older age at diagnosis of diabetes (43% of the individuals), patients who had severe hypoglycemia (26%), those with severe obesity (20%), younger age at diagnosis (1%), and those using insulin (9%).

Looking at demographic and other clustering characteristics based on these subgroups, the authors found ethnic and racial differences in these diabetes subgroups. It's kind of complicated in terms of the analysis and I'm not a biostatistician, but basically, they found that subgroup membership was associated with differences in cardiovascular risk factors and in prospective diabetes complications independent of race and ethnicity. There was a risk for having risk factors if you were in each of those subgroups. They also saw a relationship to being in a subgroup based on race and ethnicity.

They found the highest risk for complications in individuals whose onset of diabetes was in middle age and who required insulin. They also confirmed that a higher prevalence of diabetes and glucose abnormalities was seen in South Asian and Chinese individuals at similar or lower rates of adiposity compared with other racial and ethnic subgroups. That's something that we've known for a while and was reaffirmed by this study.

The South Asian subgroup, which did not include Chinese individuals but was truly South Asian, had the highest membership in the severe hyperglycemia group and the lowest beta-cell function of any of the groups. This fits with what I have seen in my own practice. Some of these patients come in very hyperglycemic with low beta-cell function, disproportionate to what I would expect in somebody with type 2 diabetes.

In summary, these authors found racial and ethnic differences across diabetes subgroups, and that there was a different risk for complications within the subgroups. I think this is really the beginning of the research that we'll do as we become more able to do genomic analyses to figure out genetically what these subgroups look like, and then how to assess individuals for risk and work with people to both diagnose diabetes earlier and treat them specifically on the basis of what they need.

Thank you very much. This has been Dr Anne Peters for Medscape.

Anne L. Peters, MD, is a professor of medicine at the University of Southern California (USC) Keck School of Medicine and director of the USC clinical diabetes programs. She has published more than 200 articles, reviews, and abstracts, and three books, on diabetes and has been an investigator for more than 40 research studies. She has spoken internationally at over 400 programs and serves on many committees of several professional organizations.

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