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BMI screening trigger for type 2 diabetes is unreliable for at-risk black, Hispanic adults



Just a single risk factor for type 2 diabetes warrants screening for the disease in black and Hispanic adults, regardless of their body mass index, according to findings presented at the annual scientific sessions of the American Diabetes Association.

Luis Rodriguez, a PhD candidate in epidemiology at the University of California, San Francisco M. Alexander Otto/MDedge News

Luis Rodriguez

The conclusions come from a review of 5,656 participants aged 45-84 years in the Multi-Ethnic Study of Atherosclerosis (MESA), an ongoing prospective cohort study. The participants had no signs of cardiovascular disease at enrollment.

The goal of the study reported at the meeting was to see if current ADA screening guidelines are appropriate across racial groups in an increasingly diverse United States. The guidelines recommend body mass index (BMI) as a trigger for screening for type 2 diabetes. The current advice is to screen any adult who has a BMI at or above 25 kg/m2 (23 kg/m2 for Asian Americans) and at least one risk factor for type 2 diabetes, such as hypertension, dyslipidemia, or physical inactivity.

Being black, Asian American, Hispanic, Pacific Islander, or American Indian is itself a risk factor, so “someone from a minority group just needs to meet the BMI criteria,” said lead investigator Luis Rodriguez, a PhD candidate in epidemiology at the University of California, San Francisco.

He and his colleagues focused on 2,383 white, 653 Chinese American, 1,459 black, and 1,161 Hispanic participants in MESA who did not have type 2 diabetes at baseline. Participants were in their early 60s at baseline, on average, and just more than half of them were women. They had five medical exams between 2000 and 2012. The investigators calculated the BMI at which each group hit a 10% risk of developing diabetes within the next 10 years.

In general, the lines crossed at a BMI of about 23 kg/m2 for Chinese Americans; 25 kg/m2 for black and Hispanic participants; and 27 kg/m2 for white participants, which is consistent with ADA advice. The guideline cut points are “appropriate for population-based screening where you may not know if the person in front of you has any diabetes risk factors,” Mr. Rodriguez said.

With known risk factors, however, BMI didn’t hold up. Black participants with one or more risk factor hit the 10% mark at a BMI of 24.7 kg/m2, Hispanics at 23.8 kg/m2, and Chinese Americans at 21.7 kg/m2, all of which are below the recommended cut-points.

“Almost 80%-90% of participants” in minority groups “who had one or more risk factors were above the 10% threshold, so if they have at least one factor, they should pretty much be screened for diabetes, regardless of BMI,” he said.

The 25-kg/m2 threshold worked for white participants; the investigators found that with one or more risk factors, white participants crossed the 10% line at a BMI of 26.2 kg/m2. In addition, white participants with no diabetes risk factors crossed the 10% mark at around a BMI of 30 kg/m2, which the investigators suggested as an appropriate screening trigger.

Participants were in their early 60s at baseline, on average, and just more than half of them were women. In all, 696 cases of type 2 diabetes were diagnosed over a median follow-up of about 9 years, which translated to an incidence rate of 11 cases per 1,000 person-years in white participants, 16 cases for Chinese Americans, 21 for black participants, and 22 for Hispanic participants. Well over half of the participants were overweight or obese at baseline, including about 80% of black and Hispanic participants.

The sample size reported in the abstract was smaller than that in the final presentation because the investigators did not adjust for diet in the final presentation, Mr. Rodriguez explained. Because some study participants did not report diet, by excluding diet from the model adjustment, the number of participants increased, as reflected in this text. Adjusting for diet did not alter the findings.

The National Heart, Lung, and Blood Institute sponsors MESA. Mr. Rodriguez was supported by a grant from the National Institutes of Health/National Institute of Diabetes and Kidney Disease. The other investigators reported having no disclosures.

SOURCE: Rodriguez L et al. ADA 2019, Abstract 115-OR.

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