Psychological interventions in adults and elderly
Mental health problems, in particular depression and anxiety, which are common in people with diabetes can adversely affect quality of life, self-care and thereby glycaemic control. Psychological problems have found to be a risk factor for increased morbidity and mortality on the longer term . In addition, eating disorders are more frequently present in females with type 1 diabetes and in persons with type 2 diabetes. Besides these clinical disorders, patients may suffer from subclinical or subsyndromal problems, e.g. elevated depressive symptoms, diabetes distress or problematic eating behaviours that do not fulfil all diagnostic criteria, but are nonetheless burdensome and interfering with healthy coping. Although the aetiology of co-morbid mental disorders and problems is not fully understood, there is a clear need for interventions, tailored to the needs of people with diabetes. In the elderly patients, impaired cognitive function is prevalent and therefore needs consideration.
Psychological interventions to improve diabetes outcomes
The efficacy of psychological interventions with regard to diabetes outcomes has been demonstrated in people with type 1 or type 2 diabetes. A meta-analysis of 25 studies assessing the efficacy of psychological interventions in people with type 2 diabetes on glycaemic control, weight and psychological distress . In 12 of them HbA1c could be significantly reduced by 0.3 standard deviations. There were no significant effects demonstrated on weight. A large impact of psychological interventions, mostly derived from cognitive behavioural therapy (CBT), on psychological distress was reported with a standardised effect size of 0.58. The patient groups treated were heterogeneous in terms of clinical characteristics. In 8 studies participants with poor glycaemic control were included; in 6 studies obesity was a selection criterion. Interestingly, specific mental health problems like depression (3 studies), anxiety or stress (each only in 1 study) were rarely important inclusion criteria.
A meta-analysis of 13 trials offering psychological interventions in type 1 diabetes demonstrated that HbA1c could be improved by 0.17 standard deviations, which corresponds to a HbA1c reduction of 0.22 percentage points, indicating a small effect size. Medical rather than psychological reasons for participating in the psychological interventions reviewed were also dominant in type 1 diabetes: poor glycaemic control, new onset diabetes, obesity or occurrence of diabetes complications. In summary, psychological interventions are modestly effective in improving medical outcomes like glycaemic control or weight in participants referred primarily for medical reasons.
Psychological interventions in mental disorders
Most of the evidenced-based psychological interventions in people with diabetes relate to depression. A meta-analysis from van der Feltz-Cornelis et al.  included 5 studies evaluating psychological interventions (mostly cognitive behavioural treatment) in people with diabetes and depression. They observed a large effect on depressive symptoms or remission of depression (median standardized effect size = 0.69) and also a large effect on glycaemic control (median standardized effect size = 0.52). However the studies included in the meta-analysis were rather small with a short follow up (4 weeks to 26 weeks). The impact of psychological interventions in depressed people with diabetes on clinical endpoints other than depression remission, e.g. incidence of complications or mortality was not assessed.
A recent Cochrane database meta-analysis  based on 8 psychological intervention studies with 1122 participants gives a somewhat different picture. The short, medium and long-term effects on depression scores were significant, but lower than described in the meta-analysis of van der Feltz-Cornelis et al. . The short term effect (end of treatment) had a standardized mean differences of -0.28 (95% CI -0.42; -0.16). The medium term effects (one to six months after treatment) were larger with standardized mean differences of -0.42 (95% CI -0.70; -0.14). The long-term effect (more than six months after treatment) was based only on 1 study, however showing a standardised effect size of -0.31 (95% CI –0.58, -0.04). Short-term depression remission rates (OR 2.88; 95% CI 1.58 to 5.25) and medium-term depression remission rates (OR 2.49; 95% CI 1.44 to 4.32) were significantly increased in psychological interventions compared to usual care. Evidence regarding glycaemic control in psychological intervention trials was heterogeneous without a significant overall effect. Effects of psychological interventions on quality of life, health care costs and medication adherence were only evaluated in few studies. Effects on these parameters were also heterogeneous and not significantly in favour for psychological intervention. Long-term effects of psychological interventions on the incidence of complications or mortality could not be analysed in this study. Recent collaborative care approaches, integrating psychological and pharmacological treatment of depression and addressing diabetes related risk factors in primary care showed a rather large effect on depression as well as on risk factors in people with diabetes. Thus collaborative care approaches  may have the potential to address metabolic risk factors in diabetes and on the long-term outcomes like morbidity and mortality.
An innovative approach using guided web-based self-help CBT treatment of depression in people with diabetes , showed moderate efficacy on depressive symptoms in the intention to treat population (standardised effect size = 0.29) and large efficacy in the per protocol population (standardised effect size = 0.70). However a rather high dropout rate indicates that online CBT has its efficacy in a selected patients group. Besides depression there is not much evidence about the efficacy of psychological interventions in people with other clinical mental disorders and diabetes. However currently there is also no evidence from empirical studies that psychological therapies recommended for the treatment in other mental disorders (e.g. phobia or addictive disorders) lack efficacy or have negative side effects if applied in people with diabetes.
Self-management education can also improve psychological outcomes
Modern structured diabetes self-management education includes psychological methods, like goal setting, problem solving, stress management, management of treatment barriers and techniques to enhance social support. Thus it is worthwhile to evaluate the impact on such programmes not only with regard to glycaemic control or self-care activities but also with regard to mental health. A meta-analysis from Cochran & Conn  on the effects of self-management education showed a significant positive impact on quality of life measures (between effect size .28 and within effect size .31). Problem specific self-management education programmes like the Blood Glucose Awareness training or the Hypos programme designed for patients with hypoglycaemia problems were able to reduce specific diabetes-related distress like fear of hypoglycaemia . A self-management education programme for people with type 2 diabetes on insulin treatment, in which mental health problems are frequently found  was able to reduce diabetes-related distress and improve the Physical composite score of the SF 12 . However, mechanisms how such ‘broad band’ programmes positively affect mental health remain to be identified. Clearly more research is needed to assess the potential of diabetes self-management education to improve sub-threshold mental disorders by increasing competence and skills and by addressing emotional problems in living with diabetes.
Psychological interventions primarily aiming at improvement of glycaemic control in people with diabetes show a moderate effect on HbA1c outcomes as well as on psychological outcomes. In people with diabetes and comorbid depression it was demonstrated that psychological interventions aiming at a well-defined mental disorder show a medium to large effect on depression status and heterogeneous effects on glycaemic control. Long-term effects of psychological treatments on clinical endpoints like incidence of complications or mortality are missing. Besides this, there is clearly a lack of evidence regarding the efficacy of psychological interventions in people with diabetes and mental disorders other than depression. However currently there is no evidence that existing psychotherapies for these disorders can not be successfully applied in people with diabetes, but further research in this area is warranted.
Sub-threshold mental disorders like elevated diabetes related distress, depressive or anxiety symptoms are clinically relevant as they have the potential to impair quality of life and result in negative clinical outcomes. Low intensity interventions like online programmes or self-management diabetes education may have the potential to reach a large group of patients and ameliorate sub-threshold mental problems and contribute to the maintenance of mental health. But in this specific area clearly more research is needed.
^ Ismail K, Winkley K, Rabe-Hesketh S (2004) Systematic review and meta-analysis of randomised controlled trials of psychological interventions to improve glycaemic control in patients with type 2 diabetes. Lancet 363: 1589-1597
^ Winkley K, Ismail K, Landau S, Eisler I (2006) Psychological interventions to improve glycaemic control in patients with type 1 diabetes: systematic review and meta-analysis of randomised controlled trials. BMJ 333: 65
^ van der Feltz-Cornelis CM, Nuyen J, Stoop C, et al (2010) Effect of interventions for major depressive disorder and significant depressive symptoms in patients with diabetes mellitus: a systematic review and meta-analysis. Gen.Hosp.Psychiatry 32: 380-395
^ Baumeister H, Hutter N, Bengel J (2012) Psychological and pharmacological interventions for depression in patients with diabetes mellitus and depression. Cochrane.Database.Syst.Rev. 12: CD008381
^ Katon WJ, Lin EH, Von Korff M, et al (2010) Collaborative care for patients with depression and chronic illnesses. N.Engl.J Med. 363: 2611-2620
^ van Bastelaar KM, Pouwer F, Cuijpers P, Riper H, Snoek FJ (2011) Web-based depression treatment for type 1 and type 2 diabetic patients: a randomized, controlled trial. Diabetes Care 34: 320-325
^ Cochran J, Conn VS (2008) Meta-analysis of Quality of Life Outcomes Following Diabetes Self-management Training. Diabetes Educ 34: 815-823
^ Cox DJ, Gonder-Frederick L, Ritterband L, et al (2006) Blood Glucose Awareness Training: What Is It, Where Is It, and Where Is It Going? Diabetes Spectr 19: 43-49
^ Schächinger H, Hegar K, Hermanns N, et al (2005) Randomized controlled clinical trial of Blood Glucose Awareness Training (BGAT III) in Switzerland and Germany. J.Behav.Med 28: 587-594
^ Polonsky WH, Fisher L, Earles J, et al (2005) Assessing Psychosocial Distress in Diabetes: Development of the Diabetes Distress Scale. Diabetes Care 28: 626-631
^ Hermanns N, Kulzer B, Maier B, Mahr M, Haak T (2012) The effect of an education programme (MEDIAS 2 ICT) involving intensive insulin treatment for people with type 2 diabetes. Patient.Educ.Couns. 86: 226-232