Use BMI of 23 to Screen for Diabetes in Asian Americans

Marlene Busko

February 17, 2015

Data from a new study that helped inform the recent American Diabetes Association recommendation to screen Asian Americans for type 2 diabetes starting at a body mass index (BMI) of 23 kg/m2 instead of 25 kg/m2 have been published.

Led by Dr Maria Rosario G Araneta (University of California, San Diego, La Jolla) the paper was published online February 9 in Diabetes Care.

Dr Araneta had presented some of these findings at the 2014 American Diabetes Association meeting; now the full consolidated data set from more than 1600 Asian Americans without a prior diagnosis of diabetes reveals that "using a BMI cut point of > 25 kg/m2 would fail to identify one out of three Asians with type 2 diabetes," Dr Araneta told Medscape Medical News. "But by lowering the cut point to 23, you would capture at least 85% of Asians with diabetes."

Indeed, this is just what ADA advised in a position paper by Dr William C Hsu (Harvard Medical School, Boston, Massachusetts) — who is also a coauthor on Dr Araneta's study — and colleagues published last month (Diabetes Care 2015;38:150-158), which was part of  the ADA's 2015 update of the Standards of Medical Care in Diabetes.

Dr Araneta says clinicians and Asian Americans need to be aware of this new lower BMI cut point for screening for type 2 diabetes so that "with earlier diagnosis we have the opportunity for early management for the prevention of diabetes complications."

Identifying Diabetes in Asians, the Fastest-Growing Ethnic Group in US

Dr Araneta explained that the ADA invited her, Dr Hsu, and colleagues to develop the position statement, since it was known that at a similar BMI, Asians have a higher prevalence of diabetes than whites.

Moreover, Asian Americans are the fastest-growing ethnic group in America and include people from the Far East (China, Japan, Korea, and Mongolia), Southeast Asia (Cambodia, Malaysia, the Philippines, Thailand, Vietnam, Indonesia, Singapore, and Laos), and South Asia (India, Pakistan, Bangladesh, Bhutan, Sri Lanka, and Nepal).

The largest numbers of American Asian populations are, in order, Chinese, Filipinos, and Asian Indians (roughly 3 to 4 million in each group), then Vietnamese, Koreans, and Japanese (roughly 1.5 million in each group), the position statement notes.

In their newly published paper, Dr Araneta and colleagues identified and consolidated data from four longitudinal studies of Asian Americans who were age 45 and older and had had a 2-hour oral glucose-tolerance test.

These were the University of California, San Diego Filipino Health Study (421 Filipinos); the North Kohala Study (115 Filipinos and 129 Japanese); the Seattle Japanese-American Community Diabetes Study (371 Japanese); and the Mediators of Atherosclerosis in South Asians Living in America (MASALA) study (609 South Asians in San Francisco and Chicago).

Type 2 diabetes was diagnosed according to 2010 ADA criteria as HbA1c > 6.5%, fasting plasma glucose > 126 mg/dL, or 2-hour post–75-g glucose challenge > 200 mg/dL.

With these criteria, 22.8% of the Filipinos, 12.9% of the Japanese, and 13.0% of the South Asians were diagnosed with type 2 diabetes.

When the screening cut point of a BMI > 25 kg/m2 was used, the sensitivity (true positives) of this screening test was only 62.7% among Filipinos, 65.7% in Japanese people, and 67.1% among South Asians.

However, a screening cut point of BMI > 23 kg/m2 would detect 89.8% of Filipinos, 84.2% of the South Asians, and 79.1% of the Japanese patients who had diabetes.

The researchers acknowledge the limitation that there were no Chinese, Vietnamese, or Korean American cohorts with 2-hour oral glucose-tolerance measurements, but they suggest that a BMI of 23 is a practical cutoff for screening for type 2 diabetes in all Asians.

"For simplicity, we recommended a cut point of 23 for all Asian Americans, although there were slight differences between these groups," Dr Araneta said.

The specificity (true negatives) of the screening test dropped from 52.85% to 28.8% when the BMI cut point was lowered from 25 to 23. However, with the BMI cut point of 23, the sensitivity was higher, "and for screening purposes, higher sensitivity is desirable to avoid missing cases, especially if the test is relatively simple and inexpensive," according to Dr Araneta and colleagues.

"A BMI cut point that has higher sensitivity despite lower specificity would be economically and clinically practical to identify Asian Americans who should undergo further glucose testing for type 2 diabetes," they write.

More Research Needed to Better Understand Risk in Asian Subgroups

However, more research is needed to better understand type 2 diabetes in different Asian subgroups, the researchers say.

"Prospective studies among aggregate Asian American subgroups must be established to better understand the unique pathophysiology of diabetes among Asian Americans and establish appropriate screening, prevention, and treatment interventions," they conclude.

This study was supported by the National Institutes of Health and the Department of Veterans Affairs. The authors report having no relevant financial relationships.

Diabetes Care. Published online February 9, 2015. Abstract

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