Publication Date

2016-06-22

Availability

Open access

Embargo Period

2016-06-22

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Psychology (Arts and Sciences)

Date of Defense

2015-06-01

First Committee Member

Maria M. Llabre

Second Committee Member

Neil Schneiderman

Third Committee Member

Marc D. Gellman

Fourth Committee Member

Ronald B. Goldberg

Fifth Committee Member

Armando Mendez

Abstract

Increased sedentary behavior has detrimental associations with cardiometabolic risk factors and depression, and has been associated with greater risk for cardiovascular disease and type 2 diabetes (T2DM), independent of engagement in moderate-vigorous physical activity (MVPA). There are limited studies of sedentary behavior in patients who already have T2DM. The aims of the study were to determine (1) whether a latent factor including self-reported daily sedentary time and daily average number of pedometer steps was associated with cardiometabolic risk factors and depressive symptoms in overweight/obese T2DM patients, and (2) whether a multi-component lifestyle intervention was successful at reducing sedentary time compared with standard care in overweight T2DM patients with significant depressive symptoms. A sample of 298 T2DM patients was recruited from Miami-area community health centers and by word-of-mouth. Participants were eligible if they were overweight/obese, had confirmed T2DM, and no evidence of CVD or renal disease. A medical history, psychosocial/behavioral measures, blood test, and pedometer data were collected. Sedentary time was self-reported with the Global Physical Activity Questionnaire (GPAQ). A subset of 111 participants with Beck Depression Inventory-II (BDI-II) total scores >11 were randomized to receive either standard care or a 12-month, 17-session lifestyle intervention, and follow-up assessments were conducted 6 months and 12 months after baseline. At baseline, structural regressions indicated that a sedentary behavior factor was significantly, positively associated with waist circumference (b = 4.47, p = .046), adjusting for age and gender, but not when further adjusting for moderate-vigorous physical activity (MVPA). The sedentary behavior factor was significantly, positively associated with a composite cardiometabolic risk score (b = .34, p = .049), adjusting for age, gender, medication use and MVPA. It was not significantly associated with body mass index, hemoglobin A1c, or scores on the BDI-II. If correcting p-values for multiple comparisons, no associations were significant at p < .05. Structural regressions using latent growth modeling showed significant reductions in minutes/day of sedentary time on the GPAQ in the intervention group compared with standard care (b = -6.54, p = .012). Intervention participants decreased their sedentary time by an average of 5.15 minutes/month over 12 months (p = .011), whereas control participants increased their sedentary time by an average of 1.39 minutes/month (p = .492). This study found evidence of associations between sedentary time and measures of adiposity and composite cardiometabolic risk in overweight T2DM patients, but no associations with other selected cardiometabolic risk factors or depressive symptoms. It found that a lifestyle intervention successfully reduced self-reported sedentary time in overweight T2DM patients with depressive symptoms. Future studies should focus on the reliable measurement of sedentary time in T2DM patients and include longer follow-up periods in order to clarify if reductions in sedentary time can reduce cardiometabolic risk and depressive symptoms in T2DM patients.

Keywords

sedentary behavior; type 2 diabetes; cardiometabolic health; lifestyle intervention

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