Effect of a Behavioral Weight Loss Intervention in People With Serious Mental Illness and Diabetes

OBJECTIVE Given the high prevalence of obesity and diabetes in patients with serious mental illness (SMI) and the lack of evidence on the effects of weight loss programs in SMI patients with diabetes, we evaluated the effectiveness of a behavioral weight loss intervention among SMI participants with and without diabetes. RESEARCH DESIGN AND METHODS Using data from ACHIEVE, a randomized controlled trial to evaluate the effects of a behavioral weight loss intervention among overweight/obese people with SMI, we assessed and compared weight change from baseline to 18 months in participants with and without diabetes using a longitudinal mixed-effects model. RESULTS Of the 291 trial participants, 82 (28.2%) participants had diabetes (34 and 48 in intervention and control groups, respectively) at baseline. Participants with diabetes were more likely to be taking antipsychotics (31.7% vs. 18.7%, P = 0.02). At 18 months, participants in the control group with diabetes lost 1.2 lb (0.6%) of body weight compared with 0.8 lb (0.7%) among those without diabetes. In the intervention group, participants with diabetes lost 13.7 lb (6.6%) of their initial body weight compared with 5.4 lb (2.9%) for those without diabetes. Corresponding net effects (intervention minus control) were 4.6 lb (2.2%) and 12.5 lb (6.0%) net weight reduction over 18 months in the no diabetes and the diabetes subgroups, respectively. However, the between-group difference in intervention effects was statistically nonsignificant (absolute weight change: P-interaction = 0.08; % weight change: P-interaction = 0.10). CONCLUSIONS A behavioral weight loss intervention is effective among overweight and obese individuals with SMI regardless of their diabetes status.