New Score: Earlier Diagnosis of Type 2 Diabetes in Blacks?

Barbara Boughton

June 19, 2013

SAN FRANCISCO — Researchers have developed a new scoring system to better identify patients at risk for metabolic syndrome, particularly among African Americans, according to work presented here at ENDO 2013: the Endocrine Society 95th Annual Meeting.

Lead author Mark DeBoer, MD, associate professor at the University of Virginia, Charlottesville, and colleagues used National Health and Nutrition Examination Survey (NHANES) data to look for factors that are more likely to contribute to increased risk for metabolic syndrome by ethnic group and gender.

"Our hypothesis in developing our scoring system was that the clinical characteristics of metabolic syndrome and how they varied by race and gender could have meaning for risk prediction," Dr. DeBoer said.

They found that high triglycerides were less likely to contribute to a diagnosis of metabolic syndrome among African Americans than other racial groups, and increased waist circumference was more important among blacks than other ethnicities.

This is important because "a diagnosis of the metabolic syndrome can trigger preventive treatment sooner, before type 2 diabetes develops or a heart attack or stroke occurs," Dr. DeBoer observed.

"As we learn more about cardiovascular disease risk and risk for diabetes, it's apparent that there's a lot of individual variation, and some of that variation is due to ethnicity and gender," commented Robert Vigersky, MD, from Walter Reed National Military Medical Center, Bethesda, Maryland, and a former president of the Endocrine Society, who was not involved in the research.

This new study provides much more specific data about metabolic syndrome and race than previously considered, he noted, adding that it was strengthened by the fact that it was NHANES, "which is well-known for the validity of its observations."

Metabolic Syndrome Components Cluster in Different Ways

One in 5 Americans has metabolic syndrome, a collection of risk factors for diabetes and cardiovascular disease, a diagnosis of which depends on having at least 3 of 5 components: large waist circumference, high blood pressure, high blood glucose levels, high triglycerides, and low levels of high-density-lipoprotein (HDL) cholesterol.

Dr. DeBoer and colleagues used data on 6881 subjects collected from 1999 to 2010 in the NHANES survey to assess how strongly different clinical characteristics contributed to the risk for metabolic syndrome among different racial groups: Hispanics, non-Hispanic whites, and non-Hispanic blacks.

While African Americans, particularly males, are less likely than other ethnic groups to be diagnosed with metabolic syndrome, they are more likely to have insulin resistance and have a higher incidence of type 2 diabetes — both of which contribute to cardiovascular risk, according to Dr. DeBoer.

However, African American men are less likely than other ethnic groups to have high triglycerides, one of the important components of the metabolic syndrome.

"By looking at individual factors that contribute to risk for metabolic syndrome, we were able to calculate how important each factor was for different race and ethnic groups, as well as how they differed by gender," Dr. DeBoer said. They found that individual components of metabolic syndrome clustered together in different ways between different sex and racial-ethnic groups, he noted.

In blacks, increased waist circumference was the strongest predictor for metabolic syndrome, he noted. "Especially among African American males, elevated waist circumference was a particularly strong and ominous sign for being diagnosed with metabolic syndrome."

The least important factor for African American males was high triglycerides.

Having an excessive waist circumference was also a more important risk factor for metabolic syndrome among African American women, according to Dr. DeBoer. By contrast, high triglycerides were the least likely to contribute to a diagnosis of metabolic syndrome among black females, he explained.

Using this information, they created a racial- and sex-specific scoring system for the severity of metabolic syndrome. They assigned numeric values to each of the 5 metabolic syndrome components, with each component having a different weight for each sex and racial-ethnic group. In African American men, for example, the HDL-cholesterol level received a higher weighting than blood pressure, indicating it may be a more ominous sign of worsening metabolic syndrome. In women, waist circumference had a higher weighting in blacks than in whites.

The researchers now plan to apply their risk prediction score to the Jackson Heart Study, a study of subjects in Jackson, Mississippi, to see how well they correlate with other predictors for cardiovascular disease risk, such as insulin resistance.

They hope to eventually use their scoring system in online calculators that could be used by physicians to calculate an individual's risk for metabolic syndrome and identify changes in that risk over time.

Such an online calculator could become a source of useful information for both clinicians and patients, Dr. Vigersky noted.

The study was funded by the National Institutes of Health. Drs. DeBoer and Vigersky reported no relevant financial disclosures.

ENDO 2013: the Endocrine Society's 95th Annual Meeting. Abstract OR48-3, presented June 18, 2013.

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