Author ORCID Identifier

https://orcid.org/0000-0002-2511-8545

Year of Publication

2019

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Nursing

Department

Nursing

First Advisor

Dr. Debra K. Moser

Abstract

Individuals with type 2 diabetes mellitus (T2DM) are at risk for developing life-threatening comorbidities such as cardiovascular disease (CVD). As a consequence, T2DM is associated with increased morbidity and mortality and decreased quality of life, thus highlighting the importance of prevention of T2DM. Further, the prevalence of T2DM is substantially greater in rural populations compared to urban populations, making rural individuals particularly appropriate targets for T2DM prevention.

T2DM is a largely preventable disease that is associated with modifiable risk factors such as poor diet, sedentary lifestyle, and obesity. Lifestyle interventions to improve these modifiable risk factors have been used to decrease the risk of developing T2DM. There is little evidence that supports lifestyle interventions as a means to decrease T2DM risk in rural populations with prediabetes, the precursor of T2DM.

The purpose of this dissertation was to determine whether rural-living individuals with prediabetes would improve modifiable risk factors, specifically diet quality by following a lifestyle intervention; thereby, decreasing their risk of developing T2DM. Specific aims for this dissertation were to, 1) examine and synthesize data from dietary interventions used to reduce risk of T2DM in rural populations on order to identify gaps and guide future research, 2) critically evaluate validity and reliability of indices used to determine diet quality in research, and 3) determine the effect of a risk reduction program on improving diet quality and glucose control (as a measure of T2DM risk) in rural adults with prediabetes and CVD risk factors.

Specific aim one was achieved by a review and synthesis of literature focused on lifestyle and dietary interventions used in rural populations to decrease the risk of developing T2DM. Common goals in these studies were a decrease in weight, decrease in dietary fat and calories, and an increase in physical activity. Decreased weight and increased physical activity were demonstrated in all eight studies, and a decrease in T2DM incidence was also demonstrated in one of the studies. However, diet quality was not adequately assessed in the majority of the studies. Furthermore, none of the studies were randomized controlled trials and only half used a control group. It was concluded that research using a more robust design is needed to determine the effect of lifestyle changes, specifically diet, on T2DM risk in rural populations. Specific aim two was addressed by a critical analysis of six common indices of dietary quality. Validity and reliability of the Healthy Eating Index, the Alternative Healthy Eating Index, the DASH diet score, the Diet Quality Index-Revised, the Healthy Diet Indicator, and the Diet Quality Score were examined. Five of the six indices are valid and reliable tools for measure diet quality but all five rely on an extensive food frequency questionnaire that may be burdensome for participants. The Diet Quality Score does not provide adequate evidence to support its use in research. It was concluded that a short, reliable, and validated diet screener may be useful in research. Specific aim three was addressed by a secondary data analysis of a longitudinal, randomized controlled study of rural residents with CVD risk factors and prediabetes. Diet quality, measured by the Mediterranean Diet Adherence Screener (MEDAS), and glucose control, measured by hemoglobin A1c, were analyzed in a subpopulation of 62 participants with prediabetes. Neither diet quality nor glucose control improved between baseline, four month, and 12 month post intervention. The reliability and validity of the MEDAS in this population is not known and may have been a factor in the lack of intervention effect related to diet quality. Participants were also not informed of their prediabetes status, thus it is not known if this knowledge would have made an impact on the outcomes of the study. In addition, the small sample size limits the statistical power to determine changes between the intervention and control groups. It was concluded that further research is needed to determine if a high quality diet will reduce T2DM risk in this rural population

Considering the disproportionate prevalence of T2DM in rural populations compared to their urban counterparts, the results of this dissertation demonstrate a continued need for interventions that decrease modifiable risk factors associated with this disease. Interventions that target obesity, poor diet quality, and sedentary lifestyles in at-risk rural populations that are culturally tailored are needed to decrease risk of developing T2DM and the comorbidities associated with this preventable disease.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2019.265

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