Impact of a weight management program on health-related quality of life in overweight adults with type 2 diabetes

Abstract

Background: Inconsistent findings have been reported regarding improved health-related quality of life (HRQOL) after weight loss. We tested the efficacy of a weight management program for improving HRQOL in overweight or obese adults diagnosed as having type 2 diabetes mellitus.

Methods: We conducted a randomized multisite clinical trial at 16 outpatient research centers with 2 treatment arms and blinded measurements at baseline and the end of year 1. A total of 5145 participants (mean [SD] age, 58.7 [6.9] years; mean [SD] body mass index [calculated as weight in kilograms divided by height in meters squared], 36.0 [5.9]; 59.5% women; 63.1% white) were randomized to an intensive lifestyle intervention (ILI) or to diabetes support and education (DSE). Main outcome measures included the 36-Item Short-Form Health Survey physical component summary (PCS) and mental health component summary (MCS) scores and Beck Depression Inventory II (BDI-II) scores. Baseline mean (SD) scores were 47.9 (7.9) for PCS, 54.0 (8.1) for MCS, and 5.7 (5.0) for BDI-II.

Results: Improved HRQOL was demonstrated by the PCS and BDI-II scores (P < .001) in the ILI arm compared with the DSE arm. The largest effect was observed for the PCS score (difference, -2.91; 99% confidence interval, -3.44 to -2.37). The greatest HRQOL improvement occurred in participants with the lowest baseline HRQOL levels. Mean (SD) changes in weight (ILI, -8.77 [8.2] kg and DSE, -0.86 [5.0] kg), improved fitness, and improved physical symptoms mediated treatment effects associated with the BDI-II and PCS.

Conclusions: Overweight adults diagnosed as having type 2 diabetes experienced significant improvement in HRQOL by enrolling in a weight management program that yielded significant weight loss, improved physical fitness, and reduced physical symptoms.

Trial registration: clinicaltrials.gov Identifier: NCT00017953.

Figure 1

CONSORT flow chart showing enrollment of participants into the Look AHEAD study.

Figure 2

Changes in measures of HRQOL as a function of treatment arm. Figure a depicts changes for PCS; Figure b depicts changes in MCS: Figure c depicts changes in BDI-II. Error bars reflect 99% confidence intervals.

Figure 3

Moderating effects of baseline scores for PCS (Figure a), MCS (Figure b), and BDI-II (Figure c) upon treatment effects related to changes in HRQOL. The two line graphs in each figure represent the regression lines depicting the relationship between baseline values and changes in HRQOL variables as a function of treatment arm.

Figure 4

Moderating effects of baseline BMI on the treatment effects related to changes in PCS. The two line graphs in Figure 4 represent the regression lines depicting the relationship between BMI and changes in PCS as a function of treatment arm.

Figure 5

A model for analyzing mediator effects using the approach described by Baron and Kenny. Note that the lower case letters (a, b, and c) refer to the following effects: a = treatment to mediator, b = mediator to outcome, and c = treatment to outcome. A lower case c′ depicts the effect of the treatment on the dependent variables with the mediator included in the model which parallels step 3 of the Baron and Kenny model.