Systematic review and meta-analysis of randomised controlled trials of psychological interventions to improve glycaemic control in patients with type 2 diabetes.

BACKGROUND Adherence difficulties and psychological problems are associated with poor glycaemic control in diabetes. We undertook a systematic review and meta-analysis of psychological therapies to assess their effectiveness in improving glycaemic control in type 2 diabetes. METHODS We searched MEDLINE, PsychINFO, EMBASE, and the Cochrane Central Register of Controlled Trials up to January, 2003. Eligible studies were randomised controlled trials that involved people with type 2 diabetes and evaluated a psychological therapy (counselling, cognitive behaviour therapy, or psychodynamic therapy) to improve diabetes control. We extracted the number of participants, their age, duration of diabetes, glycaemic control, type of psychological therapy, its mode of delivery, and type of intervention in the control group. The main outcome was long-term glycaemic control measured by percentage of glycated haemoglobin. Blood glucose concentration, weight, and psychological distress were also measured. Pooled standardised effect sizes were calculated. FINDINGS 25 trials were eligible for the review. In 12 trials, the mean percentage glycated haemoglobin was lower in people assigned a psychological intervention than in the control group (usual care, education, waiting list, or attention control); the pooled mean difference was -0.32 (95% CI -0.57 to -0.07) equivalent to an absolute difference of -0.76%. There were non-significant differences in blood glucose concentration (eight trials; -0.11 [-0.65 to 0.42]) and weight gain (nine trials; 0.37 [-0.18 to 0.93]). Psychological distress was significantly lower in the intervention groups (five trials; -0.58 [-0.95 to -0.20]). INTERPRETATION In type 2 diabetes, there are improvements in long-term glycaemic control and psychological distress but not in weight control or blood glucose concentration in people who receive psychological therapies.