According to 2010 United States Census data, the number of Asians and Pacific Islanders (APIs) in the country has risen 43% since 2000. The three largest API subgroups included people of Chinese, South Asian, or Filipino ancestry. A recent report from the U.S. National Health Interview Survey aggregated API subgroups and found substantive differences in diabetes prevalence. “Unfortunately, there is still a paucity of published data on diabetes in API subgroups in the U.S.,” says Maria Rosario Araneta, PhD. “APIs have been a population group that has largely been neglected in diabetes research.”
New Insights on Ethnic Differences in Diabetes
In 2013, researchers in the Diabetes Study of Northern California (DISTANCE) had an analysis published in Diabetes Care that estimated racial and ethnic differences in the prevalence and incidence of the disease. The DISTANCE study involved a large, multi-ethnic cohort of patients receiving care in an integrated health delivery system. It included more than 2 million adult members of Kaiser Permanente Northern California.
According to findings, there was considerable variation among the seven largest API subgroups. Pacific Islanders, South Asians, and Filipinos had the highest prevalence (18.3%, 15.9%, and 16.1%, respectively) of diabetes. These groups also had the highest incidence (19.9, 17.2, and 14.7 cases per 1,000 person-years, respectively) of diabetes among all racial and ethnic groups, including minorities who are traditionally considered high risk, such as African Americans, Latinos, and Native Americans (Figure). “Findings from this study are consistent with previous research, but there was substantial variation across the API subgroups,” adds Dr. Araneta.
The Role of BMI at Diabetes Diagnosis
Another key finding from the DISTANCE study was that Asian subgroups tended to have lower average BMIs at diabetes diagnosis than others. “The average BMI values of Asian subgroups appear to be below the threshold for obesity,” Dr. Araneta says. “This suggests that these subgroups have a higher diabetes prevalence and incidence regardless of their BMI. This information is important when it comes to recommending lifestyle interventions. For example, instructing patients to exercise more when their BMI is normal or below average may do little to reduce diabetes risk.”
Visceral Adipose Tissue Matters
In 2005, a study published in Obesity by Dr. Araneta and colleagues compared ethnic differences in visceral adipose tissue (VAT) and type 2 diabetes risk among older Filipino, African-American, and Caucasian women without known cardiovascular disease. VAT was highest among Filipinas despite having similar BMI and waist circumferences as Caucasian women; paradoxically, African-American women had the least VAT, despite having the highest BMIs and waist girth (Table). “This analysis suggests that BMI and waist circumference appear to be weaker estimates of VAT in Filipino and African-American women than in Caucasian women,” says Dr. Araneta. “Excess VAT has also been observed in Asian Indians and Japanese when compared with Caucasians at given BMI cut-off points. These findings further support the notion that clinicians should consider factors beyond BMI when screening APIs for diabetes.”
Increasing Awareness of Diabetes in Minorities
Guidelines from the American Diabetes Association note that clinicians should make special efforts to screen selected ethnic groups, including APIs, for diabetes, but Dr. Araneta says this recommendation may be overlooked by clinicians. “There needs to be greater vigilance for the appropriate screening of APIs and racial and ethnic minorities for diabetes,” she says. “We are gaining a better understanding of some of the pathophysiological differences that occur in APIs when compared with other patient groups. Clinicians need to move beyond the concept of screening APIs for diabetes only if they are obese. Many have normal or low BMIs but high levels of VAT. These high VAT levels correlate with more inflammation and insulin resistance, putting patients at risk for diabetes.”
“Clinicians need to move beyond the concept of screening APIs for diabetes only if they are obese.”
More work is still needed to understand how differences in behavioral factors, socioeconomic status, education, health literacy, language barriers, and biology influence diabetes prevalence and incidence in APIs when compared with other races and ethnicities. “We still have much to learn about A1C and whether there are different thresholds to consider when managing APIs,” says Dr. Araneta. “Dietary content may also influence the high rates of diabetes among APIs. Furthermore, research suggests that genetic factors, family history, and gestational diabetes play a role in the development of diabetes in APIs. We need to determine how strongly the risk factors influence diabetes prevalence and incidence, and then tailor treatments to address those issues.”
Dr. Araneta recommends that clinicians increase their awareness of diabetes prevalence and incidence in APIs and step up their efforts to prevent it. “The causes of differing diabetes rates by race and ethnicity are not well understood,” she says. “As we continue to gain more data on the topic, we must continue to monitor diabetes prevalence and incidence among all API subgroups to eliminate health disparities.”
Karter AJ, Schillinger D, Adams AS, et al. Elevated rates of diabetes in Pacific Islanders and Asian subgroups: The Diabetes Study of Northern California (DISTANCE). Diabetes Care. 2013;36:574-579. Available at: http://care.diabetesjournals.org/content/36/3/574.long.
Lee JW, Brancati FL, Yeh HC. Trends in the prevalence of type 2 diabetes in Asians versus whites: results from the United States National Health Interview Survey, 1997-2008. Diabetes Care. 2011;34:353-357.
Araneta MR, Barrett-Connor E. Ethnic differences in visceral adipose tissue and type 2 diabetes: Filipino, African-American, and white women. Obes Res. 2005;13:1458-1465.
Karter AJ. Race and ethnicity: vital constructs for diabetes research. Diabetes Care. 2003;26:2189-2193.
Herman WH, Ma Y, Uwaifo G, et al. Differences in A1C by race and ethnicity among patients with impaired glucose tolerance in the Diabetes Prevention Program. Diabetes Care. 2007;30:2453-2457.