Ethnic admixture affects diabetes risk in native Hawaiians: the Multiethnic Cohort.

BACKGROUND/OBJECTIVES: Obesity and diabetes rates are high in Native Hawaiians (NHs) who commonly have mixed ancestries. People of Asian ancestry experience a high risk of type 2 diabetes despite the relatively low body weight. We evaluated the impact of ethnic admixture on diabetes risk among NHs in the Multiethnic Cohort (MEC). SUBJECTS/METHODS: On the basis of self-reports, 11 521 eligible men and women were categorized into NH/white, NH/other, NH alone, NH/Asian and the most common three ancestry admixture, NH/Chinese/white. Cox proportional hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated with the NH/white category as the reference group; covariates included known confounders-that is, body mass index (BMI), dietary and other lifestyle factors. RESULTS: The NH alone category had the highest proportion of overweight and obese individuals and the NH/Asian category the lowest proportion. During 12 years of follow-up after cohort entry at 56 years, 2072 incident cases were ascertained through questionnaires and health plan linkages. All NH categories had higher HRs than the NH/white category before and after adjustment for BMI. In the fully adjusted models, the NH/Asian category showed the highest risk (HR=1.45; 95% CI: 1.27-1.65), followed by NH/other (HR=1.20; 95% CI: 1.03-1.39), NH/Chinese/white (HR=1.19; 95% CI: 1.04-1.37) and NH alone (HR=1.19; 95% CI: 1.03-1.37). The elevated risk by Asian admixture was more pronounced in normal weight than overweight/obese individuals. CONCLUSIONS: These findings indicate that Asian admixture in NHs is associated with a higher risk for type 2 diabetes independent of known risk factors and suggest a role for ethnicity-related genetic factors in the development of this disease.

Translating the Diabetes Prevention Program in Native Hawaiian and Pacific Islander communities: the PILI 'Ohana Project.

Native Hawaiians/Pacific Islanders experience a high prevalence of overweight/obesity. The Diabetes Prevention Program Lifestyle Intervention (DPP-LI) was translated into a 3-month community-based intervention to benefit these populations. The weight loss and other clinical and behavioral outcomes of the translated DPP-LI and the socio-demographic, behavioral, and biological factors associated with the weight loss were examined. A total of 239 Native Hawaiian/Pacific Islander adults completed the translated DPP-LI through four community-based organizations (CBOs). Changes from pre- to post-intervention assessments in weight, blood pressure, physical functioning, exercise frequency, and fat in diet were measured. Significant improvements on all variables were found, with differences observed across the four CBOs. CBOs with predominately Native Hawaiian and ethnically homogenous intervention groups had greater weight loss. General linear modeling indicated that larger baseline weight and CBO predicted weight loss. The translated DPP-LI can be effective for Native Hawaiians/Pacific Islanders, especially when socio-cultural, socio-economic, and CBO-related contextual factors are taken into account.

Mediators of lifestyle behavior change in Native Hawaiians: initial findings from the Native Hawaiian Diabetes Intervention Program.

OBJECTIVE: To examine the association of stage of change with diet and exercise behaviors in response to a lifestyle intervention for Native Hawaiians (NHs). RESEARCH DESIGN AND METHODS: A family ('ohana) support lifestyle intervention was compared with a standard intervention in NHs with or at risk for diabetes in two rural communities in Hawaii (n = 147). Stage of change, as a hypothesized mediator of behavior change, and dietary and exercise behaviors were measured at baseline and at 1 year postintervention. RESULTS: Stage of change was significantly associated with positive dietary and exercise behaviors. NHs receiving the 'ohana support (OS) intervention were more likely to advance from pre-action to action/maintenance for fat intake and physical activity than the group who received the standard intervention. Participants in the OS group who advanced from pre-action to action/maintenance showed more improvement in fat intake and physical activity than those in the standard group. CONCLUSIONS: These initial findings suggest that stage of change is an important factor in mediating lifestyle behavior changes in persons with or at risk for diabetes and merits further study among minority populations at high risk for diabetes.

Prevalence of glucose intolerance among Native Hawaiians in two rural communities. Native Hawaiian Health Research (NHHR) Project.

OBJECTIVE: To estimate prevalence of type 2 diabetes and impaired glucose tolerance (IGT) among a population of native Hawaiians in two rural communities. RESEARCH DESIGN AND METHODS: Prevalence of glucose intolerance was assessed in two rural communities by history (confirmed by record review) or with a 75-g oral glucose tolerance test according to World Health Organization criteria. Anthropometric and demographic data were also obtained. A short survey was used to estimate the prevalence of known diabetes among nonparticipants. Prevalence rates were adjusted using the standard world population of Segi. RESULTS: A total of 574 native Hawaiians age > or = 30 years participated. The crude prevalence of IGT and type 2 diabetes were 15.5 and 20.4%, respectively. Only IGT prevalence was significantly higher (P = 0.03) among women (18.7%) than among men (10.9%). Prevalence of glucose intolerance was significantly associated with BMI, waist circumference, and waist-to-hip ratio (WHR). After adjusting for age and BMI, waist circumference and WHR were significantly and independently associated with type 2 diabetes prevalence only among women. Prevalence of type 2 diabetes was not significantly associated with the percentage of Hawaiian ancestry after adjusting for age. CONCLUSIONS: This study observed a high prevalence of glucose intolerance associated with being overweight among native Hawaiians. Age-adjusted type 2 diabetes prevalence was four times higher than among the U.S. National Health and Nutrition Examination Survey (NHANES) II population. Prevalence was high despite high rates of admixture with other ethnic groups of Hawaii, suggesting that these other Asian and Pacific Island populations share similar susceptibility to type 2 diabetes risk.

The insulin resistance syndrome in native Hawaiians. Native Hawaiian Health Research (NHHR) Project.

OBJECTIVE: To investigate whether fasting hyperinsulinemia is associated with a clustering of cardiovascular disease (CVD) risk factors, manifesting as the insulin resistance syndrome (IRS), in a population of native Hawaiians. RESEARCH DESIGN AND METHODS: A total of 574 native Hawaiians > or = 30 years of age were examined for blood pressure, waist-to-hip ratio (WHR), BMI, oral glucose tolerance, and fasting lipid, insulin, and C-peptide concentrations. All statistical analyses (n = 384) excluded 190 individuals who had NIDDM or who were taking hypertension medication. Using logistic regression analysis, fasting insulin and C-peptide levels were compared with CVD risk factors (glucose intolerance, hypertension, central adiposity, elevated triglyceride levels, and low HDL cholesterol levels) after adjusting for age and obesity. RESULTS: Sixty-six percent of native Hawaiians were overweight or obese, and 70% were found to have central adiposity. Fasting insulin concentrations were correlated with BMI, WHR, blood pressure, and triglyceride, HDL cholesterol, and glucose concentrations. Fasting insulin was also significantly associated with an increasing number of CVD risk factors in each participant (P < 0.001). Fasting insulin and C-peptide concentrations were independently associated with glucose intolerance, high triglyceride levels, and low HDL cholesterol levels. However, only fasting C-peptide concentrations were independently associated with hypertension and central adiposity. Apparent differences in the correlates of fasting insulin and C-peptide may be related to multiple factors and warrant further evaluation. CONCLUSIONS: This study provides cross-sectional data confirming the existence of the IRS in native Hawaiians. However, further longitudinal studies are needed to examine the relationship of insulin resistance and/or surrogate markers to increased rates of NIDDM and CVD mortality in native Hawaiians.