Date of Award

Fall 1-8-2016

Degree Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

Public Health

First Advisor

Dora Il'yasova, PhD

Second Advisor

Ruiyan Luo, PhD

Abstract

ABSTRACT

Insulin Dynamic Measures and Weight Change

By

Noreen Kloc

B.S. Computer Information Technology, Purdue University

December 7, 2015

INTRODUCTION: Weight gain and obesity are risk factors for insulin resistance that can lead to type 2 diabetes and cardiovascular disease; however, there is a complicated interplay between insulin sensitivity (SI), fasting insulin, acute insulin response (AIR), and disposition index (DI) and the relationship of these dynamic measures with weight change is not well understood.

AIM: The aim of this study was to investigate the relationships between insulin dynamic measures, SI, fasting insulin, AIR, and DI, with weight change during a 5-years follow-up period in the multi-ethnic cohort of the Insulin Resistance Atherosclerosis Study (IRAS).

METHODS: Data on 879 men and women of Hispanic, non-Hispanic White, and African-American race/ethnicity aged 40-69 years were obtained at baseline (1992-1994) and at 5 year follow-up. Crude associations between the insulin dynamic measures and weight change were evaluated using Kruskal-Wallis test and the relationships between log-transformed insulin-related variables were examined using Spearman rank-order analysis. Multivariate regression models evaluated associations of interest adjusted for age, sex, ethnicity, and diabetes status in a time-dependent manner using mixed models.

RESULTS: Insulin sensitivity SI inversely coevolves with weight, i.e. greater weight is predicted by lower SI at any time point. To answer the question whether SI is the cause or a consequence of weight change, we examined the associations with the baseline values and a change in SI. In this model, both the baseline SI and change in SI were inversely correlated with weight gain. A similar approach showed that baseline values and change in fasting insulin were directly associated with weight gain. Weight change over time was associated with AIR, i.e. increases in AIR and greater AIR at baseline predicted weight gain. We did not find strong relationships between DI and weight change.

DISCUSSION: These results suggest that insulin sensitivity and insulin secretion can modulate weight in a non-diabetic population.

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