Date of Award

5-14-2019

Degree Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

Public Health

First Advisor

Dora Il'yasova

Second Advisor

Ruiyan Luo

Abstract

Type 2 diabetes (T2DM) is a chronic condition affecting 1 in every 10 adults in the United States. There is evidence that individuals with greater levels of F2-isoprostanes at similar levels of adiposity have reduced risk of T2DM. F2-isprostanes have been validated as markers of oxidative status in animal and human studies. Many cross-sectional studies found correlations between F2-isprostanes and adiposity measured as body mass index (BMI). The connection of F2-isprostanes to the lower risk of diabetes and BMI suggests that these markers can be interpreted as a part of some compensatory mechanisms involved in metabolic adaptation to body fat accumulation. The purpose of this study was to compare the additive relationship between BMI, as a measure of adiposity, and 2,3-dinor-iPF2α-III (F2-isoP), as a measure of adaptation to increased BMI, to a model that proposes multiplicative relationships between F2-isoP to BMI expressed by the ratio of F2-isoP to BMI. The present analysis utilizes data from the Insulin Resistance Atherosclerosis Study (IRAS), a multicenter prospective cohort designed to study the relationships between insulin resistance, type 2 diabetes, cardiovascular disease risk factors and behaviors in a diverse population including non-Hispanic whites, African Americans, and Hispanics. Between October 1992 and April 1994 approximately 1625 participants, between 40-69 years of age at baseline, were recruited from four U.S. clinical centers located in San Antonio, TX; San Luis Valley, CO; Oakland, CA; Los Angeles, CA. Wilcoxon-rank sum/ Kruskal-Wallis tests and Wald-chi-square test were used to describe the study population. Logistic regression models were used assess the relationships between the exposures of interest as well as age, gender, race/ethnicity, glucose tolerance status. The additive model estimated the association between F2-isoP and the risk of T2DM with BMI being a covariate. The multiplicative model estimated the association between F2-isoP/BMI ratio, F2-isoP and the risk of T2DM. Percent differences of odds ratios were calculated between the two models, with >10% difference indicating meaningful change. The results from the analysis show that the new variable F2-isoP/BMI ratio does not clearly indicate whether the multiplicative model represents a better way to evaluate the relationships between F2-isoP, BMI and risk for T2DM. Evaluation of the additive and multiplicative models for outcomes—such as weight change, decrease in insulin resistance, blood pressure and others—might clarify whether the additive or multiplicative relationships, between F2-isoP and BMI, better predict these outcomes.

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