OAKLAND, Calif., Oct. 15, 2012 – Rates of diagnosed diabetes are much higher among some Asian subgroups than is apparent when aggregating all Asians as a whole, according to a new study by the Kaiser Permanente Northern California Division of Research and the University of California, San Francisco which appears in the current online issue of Diabetes Care.
In this first study to look at Asian subgroup differences in a population with uniform access to health care, there was considerable variation among the seven largest Asian and Pacific Islander subgroups. Pacific Islanders, South Asians and Filipinos had the highest diabetes prevalence (18.3 percent, 15.9 percent and 16.1 percent respectively) and incidence (19.9, 17.2, 14.7 cases per 1,000-person years, respectively) among all racial/ethnic groups, including minorities traditionally considered high risk, such as African Americans, Latinos and Native Americans.
“Our findings are consistent with national surveillance which reports that Asians generally have a higher prevalence of diabetes relative to non-Hispanic whites, but lower than that of African Americans and Latinos,” explained Andrew Karter, PhD, a senior research scientist with the Kaiser Permanente Northern California Division of Research and the lead author of the study.
“However, when looking at the Asian subgroups separately, we find that Pacific Islanders, South Asians and Filipinos stand out as having greater risk. Studying diabetes in Asians ‘as a whole’ obscured these subgroup differences because the high diabetes risk among Pacific Islanders, South Asians and Filipinos was counterbalanced by much lower rates among the large population of Chinese and several smaller Asian subgroups. ”
As part of the Diabetes Study of Northern California (DISTANCE), researchers analyzed 1,704,363 adult members of Kaiser Permanente in Northern California, and estimated racial/ethnic differences in diabetes prevalence and incidence in a large multi-ethnic population of patients receiving care in an integrated health care delivery system.
The number of Americans of Asian and Pacific Islander ethnicity increased by 43 percent between the 2000 and 2010 censuses, and they now comprise 5 percent of the U.S. population. National health statistics typically have lumped all Asians into a single group when evaluating racial differences in health outcomes, precluding evaluation of subgroup differences. Most national health surveys before 2000 classified Asians as “other race” or, if recognized, combined them with Pacific Islanders.
"That would be like combining blacks, Latinos and whites together into one ethnic group," said Alka Kanaya, MD, an associate professor of medicine at the University of California, San Francisco and a co-author on the study. “As a result, the variation among Asian and Pacific Islanders subgroups has been neglected. In fact, the aggregated statistics may be completely misleading given the variation in the representation of each subgroup across the U.S.”
The researchers point out that the findings suggest an opportunity for improving diabetes prevention efforts. “Targeting patients based on body mass index (BMI) or obesity alone may miss individuals in Asian subgroups who are often at high risk for diabetes even when they are not obese,” said Karter.
This study is part of Kaiser Permanente’s larger ongoing work to better understand and address health disparities. In another study, published in the journal Diabetologia in 2011, researchers found that African American women who develop gestational diabetes mellitus during pregnancy face a 52 percent increased risk of developing diabetes in the future compared to white women who develop GDM during pregnancy. In 2009 in the Ethnicities and Disease journal, Kaiser Permanente researchers reported that more than 10 percent of women of Chinese and Korean heritage may be at risk for developing diabetes during pregnancy.
Additional authors on the study include Dean Schillinger, MD, with the University of California, San Francisco Division of General Internal Medicine; Alyce S. Adams, PhD, and Howard H. Moffet, MPH, with the Kaiser Permanente Northern California Division of Research; and Nancy Adler, PhD, with the University of California, San Francisco Center for Health and Community.
Funding for the research was provided by the National Institute of Diabetes and Digestive and Kidney Diseases.