Abstract
Background: Poor lifestyle choices, coupled with the obesity
epidemic, have dramatically increased the number of adults living
with prediabetes. Compared with type 2 diabetes, much less is known
about the effects of prediabetes on biological, physical, and
psychological risk factors that heighten adverse cardiovascular
disease (CVD) outcomes among overweight/obese adults. The primary
aim of the study was to compare baseline biological, physical, and
psychological risk factors for CVD among overweight/obese adults
with and without prediabetes. Methods: A secondary data analysis
was performed using a large database of healthy adults employed at
an academic health sciences center located in the southeastern
United States. Baseline biological, physical and psychological risk
factors were included in the analysis. Linear or logistic
regression models were used to evaluate the association between
prediabetes and biological, physical, and psychological risk
factors, controlling for age, gender and education. Results: Three
hundred forty one overweight/obese participants were included in
the analysis: 44 had prediabetes (fasting blood
glucose≥100 but <126 mg/dl) 297 were without
prediabetes. Participant median age with and without prediabetes
was 55 and 48 (p<0.0001), respectively. The majority of
participants were Caucasian (69.5%), high income (median income
$100,000-$150,000), and well-educated (median education level 18
years). There were significant differences for several baseline
biological risk factors among prediabetics versus nonprediabetics
and included higher fasting blood glucose (104.8 vs 86.3 mg/dl,
p<0.0001), body mass index (31.2 vs 28.8 kg/m2, p<0.017),
waist-hip ratio (0.9 vs 0.8, p=0.014), triglycerides (111 vs 91
mg/dl, p=0.0002). Prediabetics were also more likely to be insulin
resistant (47.7% vs 14.1%, p<0.0001) than nonprediabetics. Among
the baseline physical risk factors examined, participants with
prediabetes had much lower cardiorespiratory fitness than those
without prediabetes (28.5 vs 32 ml/kg/min, p=0.029). Participants
with prediabetes were also more likely to have lower self-reported
physical functioning (53.8 vs 49.9, p=0.003). No differences in
baseline psychological risk factors were observed between groups.
Conclusions: Findings from this study suggest that healthy
overweight/obese adults with prediabetes were likely at higher
biological and physical risk for CVD at baseline compared to those
without prediabetes. Early intervention to improve CVD risk
progression among persons with prediabetes is essential.
Table of Contents
Table of Contents Chapter 1. Statement of the Problem 1
Introduction 1 Background 1 Purpose of the Study 8 Significance of
the Study 10 Summary 11 Chapter 2. Review of the Literature 12
Introduction 12 Epidemiology of Type 2 Diabetes Mellitus and
Prediabetes 12 Lifestyle Interventions and Type 2 Diabetes Mellitus
Prevention 16 Prediabetes and Cardiovascular Disease 20 Prediabetes
as an Independent Risk Factor for Cardiovascular Disease 20
Mechanisms of Vascular Damage of Prediabetes 23 Conceptual
Framework 23 Overview 23 Theoretical Assumptions 26 Age 28 Gender
28 Educational Level 29 Overweight/Obesity 30 Biological Risk
Factors 35 Physical Risk Factors 48 Psychological Risk Factors 54
Health Outcomes 57 Summary 77 Chapter 3. Methodology 79
Introduction 79 Research Design 79 Design 79 Setting and Sample 83
Sample Size and Power Calculation 85 Variables, Definitions, and
Measures 86 Overview 87 Conceptual and Operational Definitions
(Instruments) 87 Statistical Analysis 93 Summary 96 Chapter 4.
Results 98 Baseline Sample Characteristics 98 Baseline Sample
Characteristics by Prediabetic State 98 Baseline Characteristics of
Biological, Physical, and Psychological Risk Factors 99 Baseline
Characteristics of Biological Risk Factors 99 Differences in
Biological Risk Factors Between Participants With and Without
Prediabetes at Baseline 101 Baseline Characteristics of Physical
Risk Factors 102 Baseline Characteristics of Psychological Risk
Factors 103 Differences in Physical and Psychological Risk Factors
Between Participants With and Without Prediabetes at Baseline 104
Changes in Biological, Physical, and Psychological Risk Factors At
One-Year Follow-up Visit 105 Changes in Biological Risk Factors at
One-Year Follow-up Visit 105 Compare Changes in Biological Risk
Factors at One-Year Follow-up Visit Between Those With and Without
Prediabetes 111 Changes in Physical Risk Factors at One-Year
Follow-up Visit 112 Compare Changes in Physical Risk Factors at
One-Year Follow-up Visit Between Those With and Without Prediabetes
114 Changes in Psychological Risk Factors at One-Year Follow-up
Visit 115 Compare Changes in Psychological Risk Factors at One-Year
Follow-up Visit Between Those With and Without Prediabetes 117
Checking for Multicollinearity Assumptions 118 Chapter 5.
Discussion 119 Introduction 119 Summary of Major Findings 119
Comparison to Findings of Previous Literature/Research 120
Strengths of the Study 140 Limitations of the Study 141
Recommendations for Future Research 144 Implications for Clinical
Practice 147 Conclusions 148 Appendices 151 Appendix A. Mechanisms
of Vascular Damage in Prediabetes 151 Appendix B. Literature Review
Table 162 Appendix C. Underlying Pathophysiological Mechanisms
Associated With Dyslipidemia 184 Appendix D. Study Approval from
the Institutional Review Board 186 Appendix E. Checking for
Multicollinearity Assumptions 187 Appendix F. Copies of the Study
Instruments 193 Beck Depression Inventory-II 193 CAPS Typical Week
Physical Activity Questionnaire 197 References 202
About this Dissertation
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