Elevated rates of diabetes in Pacific Islanders and Asian subgroups: The Diabetes Study of Northern California (DISTANCE)

Abstract

Objective: We estimated the prevalence and incidence of diabetes among specific subgroups of Asians and Pacific Islanders (APIs) in a multiethnic U.S. population with uniform access to care.

Research design and methods: This prospective cohort analysis included 2,123,548 adult members of Kaiser Permanente Northern California, including 1,704,363 with known race/ethnicity (white, 56.9%; Latino, 14.9%; African American, 8.0%; Filipino, 4.9%; Chinese, 4.0%; multiracial, 2.8%; Japanese, 0.9%; Native American, 0.6%; Pacific Islander, 0.5%; South Asian, 0.4%; and Southeast Asian, Korean, and Vietnamese, 0.1% each). We calculated age-standardized (to the 2010 U.S. population) and sex-adjusted diabetes prevalence at baseline and incidence (during the 2010 calendar year). Poisson models were used to estimate relative risks.

Results: There were 210,632 subjects with prevalent diabetes as of 1 January 2010 and 15,357 incident cases of diabetes identified during 2010. The crude diabetes prevalence was 9.9% and the incidence was 8.0 cases per 1,000 person-years and, after standardizing by age and sex to the 2010 U.S. Census, 8.9% and 7.7 cases per 1,000 person-years. 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) and the highest incidence (19.9, 17.2, and 14.7 cases per 1,000 person-years, respectively) of diabetes among all racial/ethnic groups, including minorities traditionally considered high risk (e.g., African Americans, Latinos, and Native Americans).

Conclusions: High rates of diabetes among Pacific Islanders, South Asians, and Filipinos are obscured by much lower rates among the large population of Chinese and several smaller Asian subgroups.

Figure 1

Standardized diabetes incidence rate (per 1,000 person-years) for each race/ethnic group (2010, KPNC). Identified 15,357 new cases of medically diagnosed diabetes in 2010 among the adults (≥18 years of age) without pre-existing diabetes in KPNC on 1 January 2010. The incidence density was directly standardized to the 2010 U.S. Census. All Asian included Filipino, Chinese, Japanese, South Asian, Southeast Asian, Korean, Vietnamese, unspecified Asian, and multiracial Asian; API included the identical groups as all Asian with the addition of Pacific Islanders.

Figure 2

BMI among adult (≥18 years of age) members of KPNC by race for those with prevalent diabetes (n = 194,614), newly identified diabetes (n = 13,392), and subjects remaining normoglycemic (n = 1,496,357) during calendar year 2010. BMI measured during calendar year 2009 among the 1,704,363 adult members of KPNC with known ethnicity.