Group cognitive behavioural therapy and weight regain after diet in type 2 diabetes: results from the randomised controlled POWER trial

AIMS/HYPOTHESIS: Weight-loss programmes for adults with type 2 diabetes are less effective in the long term owing to regain of weight. Our aim was to determine the 2 year effectiveness of a cognitive behavioural group therapy (group-CBT) programme in weight maintenance after diet-induced weight loss in overweight and obese adults with type 2 diabetes, using a randomised, parallel, non-blinded, pragmatic study design. METHODS: We included 158 obese adults (median BMI 36.3 [IQR 32.5–40.0] kg/m(2)) with type 2 diabetes from the outpatient diabetes clinic of Erasmus MC, the Netherlands, who achieved ≥5% weight loss on an 8 week very low calorie diet. Participants were randomised (stratified by weight loss) to usual care or usual care plus group-CBT (17 group sessions). The primary outcomes were the between-group differences after 2 years in: (1) body weight; and (2) weight regain. Secondary outcomes were HbA(1c) levels, insulin dose, plasma lipid levels, depression, anxiety, self-esteem, quality of life, fatigue, physical activity, eating disorders and related cognitions. Data were analysed using linear mixed modelling. RESULTS: During the initial 8 week dieting phase, the control group (n = 75) lost a mean of 10.0 (95% CI 9.1, 10.9) kg and the intervention group (n = 83) lost 9.2 (95% CI 8.4, 10.0) kg (p = 0.206 for the between-group difference). During 2 years of follow-up, mean weight regain was 4.7 (95% CI 3.0, 6.3) kg for the control group and 4.0 (95% CI 2.3, 5.6) kg for the intervention group, with a between-group difference of −0.7 (95% CI −3.1, 1.6) kg (p = 0.6). The mean difference in body weight at 2 years was −1.2 (95% CI −7.7, 5.3) kg (p = 0.7). None of the secondary outcomes differed between the two groups. CONCLUSIONS/INTERPRETATION: Despite increased treatment contact, a group-CBT programme for long-term weight maintenance after an initial ≥5% weight loss from dieting in obese individuals with type 2 diabetes was not superior to usual care alone. TRIAL REGISTRATION: Trialregister.nl NTR2264 FUNDING: The study was funded by the Erasmus MC funding programme ‘Zorgonderzoek’ (grant 2008-8303). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00125-017-4531-9) contains peer-reviewed but unedited supplementary material, which is available to authorised users.