Nutritional Risk Factors for Type 2 Diabetes in the Multiethnic Cohort

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DESCRIPTION (provided by applicant): The risk to develop type 2 diabetes is considerably higher among individuals with ethnic backgrounds other than Caucasian. Native Hawaiians experience an extremely high risk for diabetes and Japanese-Americans also suffer a disproportionate rate of the disease despite their relatively low body weight. The importance of body weight and nutritional composition appears to differ by ethnic background. The Multiethnic Cohort (MEC) was established in 1993-96 to investigate diet and cancer among different ethnic groups. The Hawaii component consists of 103,898 individuals 40 years and older, primarily of Caucasian, Japanese, and Native Hawaiian ancestry. Participants entered the study by completing a self-administered mailed survey that included a quantitative food frequency questionnaire. The data show substantial variations in dietary intakes and non-dietary risk factors both within and among ethnic groups. The specific aims of this project are to link the MEC with registries from the two major insurers in Hawaii that identify patients with a confirmed diagnosis of diabetes; to estimate the current prevalence and the annual incidence of diabetes among Caucasians, Japanese, and Native Hawaiians in the MEC; examine the association of overweight, obesity, adult weight change, waist circumference, physical activity, excess energy intake, dietary fiber, glycemic index, and dietary patterns with the occurrence of diabetes; and explore the differential role of these anthropometric, behavioral, and nutritional factors by ethnicity among Caucasian, Japanese, and Native Hawaiian study subjects. Two health plans in Hawaii cover an estimated 90% of MEC members and maintain diabetes registries. Through a probability based linkage procedure using name, sex, date of birth, and ZIP code of residence, these diagnoses will be added to the MEC data base. A linking protocol that agrees with current privacy rules and maintains the confidentiality of all health records will be developed. We expect a linked dataset with approximately 16,000 cohort members who were diagnosed with type 2 diabetes; of those, 7,000 are estimated to be new cases diagnosed since entry into the cohort. We will apply Cox's regression to determine the relative risk of developing diabetes since entry into the cohort associated with overweight, obesity, weight gain, physical activity, excess energy intake, dietary fiber, glycemic index, and dietary patterns while adjusting for confounding variables and stratifying by sex and ethnicity. The epidemic of diabetes leads to a large number of premature deaths. This project will make a contribution to the prevention of this disease that not only carries a huge burden of morbidity and mortality by itself, but also predisposes its carriers to cardiovascular disease and other serious conditions, in particular among Native Hawaiians and Asian-Americans. A better understanding of dietary and behavioral factors related to excess body weight and diabetes in Japanese and Native Hawaiians will help in developing preventive strategies to modify lifestyle factors.