Correlates of health-related quality of life in overweight and obese adults with type 2 diabetes.

Objective: This paper describes and examines conceptually relevant correlates of health-related quality of life (HRQL) in overweight or obese persons with type 2 diabetes. Research Design and Procedures: The investigation was a cross-sectional study of 5145 overweight or obese adults with type 2 diabetes between the ages of 45 and 74 years. Analyses examined the relationship that demographic characteristics, disease burden, and cardiovascular fitness had with HRQL: the Short Form 36 (SF-36) and the Beck Depression Inventory (BDI) II.

Results: Means for the SF-36 physical component summary (PCS) scores, the mental component summary scores, and the BDI-II were as follows: 47.0, 54.0, and 5.7. Less desirable PCS scores were related to several comorbidities, insulin use, physical complaints, a high BMI, low metabolic equivalent (MET) capacity, and lower education. Interactions between categories of obesity and MET capacity revealed that greater BMI was related to lower PCS scores when individuals had lower MET capacities yet was absent for those individuals who had higher MET capacities. In addition, although greater BMI was associated with more severe depressive symptomatology, this association was the most dramatic for those with class III obesity who had low MET capacity.

Discussion: Although participants in Look AHEAD had a favorable profile on the SF-36 and the BDI-II at baseline, lower PCS scores were related to disease severity and the presence of other comorbidities. More important, although the temporal ordering of associations cannot be determined in a cross-sectional design, the interactions between obesity class and MET capacity suggest that the adverse effect of BMI on PCS and BDI-II scores may be buffered by higher MET capacities.