This well-conducted review assessed the effectiveness of educational interventions for adults with diabetes. The authors highlighted the poor quality of the evidence and concluded that education, as part of an intensification of treatment, produces improvement in diabetic control in type 1 diabetics. It remains unclear which features of education may be beneficial for patients with type 2 diabetes.

To assess the clinical- and cost-effectiveness of patient education models for adults with type 1 and type 2 diabetes.

MEDLINE, EMBASE, PubMed (over the previous 6 months), CINAHL, PsycLIT, ERIC, the Cochrane Library, the Science Citation Index, the Social Sciences Citation Index, National Research Register, MRC Clinical Trials Directory, an Early Warning System database, Current Controlled Trials, DARE, HTA, NHS EED and EconLit were searched; the search terms were listed. The reference lists of retrieved studies were also checked. Experts were consulted for additional published, unpublished, and ongoing studies. Studies that were not published in English were excluded, as were studies only available as an abstract.

Study designs of evaluations included in the review

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) with a concurrent control were eligible.

Specific interventions included in the review

Educational programmes that were compared with each other or with usual care were eligible. The interventions had to be described in sufficient detail such that they could be reproduced, e.g. content of programme, method of delivering the information, number of sessions, and target population. Studies that evaluated specialised psychological interventions aimed at changing an individual's behaviour were excluded. Studies that included these approaches as part of a multifaceted educational intervention were included. Investigations that focused on a particular complication of diabetes (e.g. foot care) were excluded. Both group and individual targeted interventions were eligible.

All the included studies in type 1 diabetes were of interventions that attempted to educate on a wide range of topics related to diabetes self-management; most were intensive treatment programmes with some educational component. The interventions in studies of type 2 diabetes were varied; some were aimed at multiple facets of self-management, while others focused on specific aspects such as diet and exercise.

Participants included in the review

Adults with newly diagnosed or established type 1 or type 2 diabetes mellitus were included in the review. Of the included studies, 4 were of type 1 diabetes, 16 were of type 2 diabetes, and 4 included adults with either type 1 or type 2 diabetes. Demographic details were listed in the review.

Outcomes assessed in the review

The eligible outcomes were assessed under three categories: diabetic control, diabetic end points, and quality of life and cognitive measures. Diabetic control included glycated haemoglobin, blood-pressure, and body mass index or weight. Diabetic end points referred to hypoglycaemic episodes, retinopathy and nephropathy, and rate of hospital admissions. Quality of life and cognitive measures included validated disease-specific and generic measures of quality of life, and assessment of knowledge and attitudes. A minimum of 12 months follow-up for the assessment of outcomes was necessary.

How were decisions on the relevance of primary studies made?

One reviewer screened study titles, which were checked by a second reviewer. Two reviewers independently screened the study abstracts. One reviewer selected full publications and a second reviewer checked them. Any discrepancies were resolved through discussion.

The authors used the criteria listed in the Centre for Reviews and Dissemination Report 4 to critically appraise their studies. One reviewer applied the validity criteria and a second reviewer checked them. Any discrepancies were resolved through discussion.

One reviewer extracted the data using a data extraction form, and a second reviewer checked the extraction. Any discrepancies were resolved through discussion.

How were the studies combined?

The studies were combined in a narrative discussion according to the type of diabetes (i.e. type 1, type 2, or combination). Within these sections the effectiveness data were discussed according to the outcome measure.

How were differences between studies investigated?

Between-study differences are apparent from the tables of study details and were discussed in the text.

Twenty-four studies, consisting of 18 RCTs and 6 CCTs, were included (n=2,888).

The quality of methodology and reporting was poor.

Type 1 diabetes (2 RCTs and 2 CCTs).

Four studies evaluated interventions for patients with type 1 diabetes. These showed significant and long-lasting improvements in metabolic control and reductions in complications. However, these effects may not be attributable to education alone. One RCT, which compared self-management education with usual care, reported significant reductions in glycated haemoglobin, nephropathy, and retinopathy in the treatment group, in addition to more frequent hypoglycaemic episodes.

Type 2 diabetes (13 RCTs and 3 CCTs).

Sixteen trials investigated the effectiveness of educational interventions in type 2 diabetes: 6 RCTs and 2 CCTs assessed complete self-management education, while 7 RCTs and 1 CCT investigated interventions that were more specific in their approach to self-management education (either diet or exercise, or a combination of the two). The studies did not find consistent results. Some found improvements in metabolic control, quality of life, or other psychosocial outcomes; others did not report any significant effects of the educational interventions. It is unclear what, if any, characteristics of educational interventions may be beneficial.

Type 1 and type 2 mixed (3 RCTs and 1 CCT).

Studies of both type 1 and type 2 diabetes reported mixed results and only the poor-quality studies demonstrated significant effects.

The cost-effectiveness of patient education models for diabetes was assessed. The findings from the literature review did not provide any information about the cost-effectiveness of educational models. As the costs of education programmes are low, only modest effectiveness is required to make them cost-effective.

Education as part of an intensification of treatment produces improvement in diabetic control in type 1 diabetes. It remains unclear which features of education may be beneficial for patients with type 2 diabetes. The quality of reporting and methodology was generally found to be poor.

The review question was clear in terms of the study design, participants, intervention and outcomes of interest. A number of electronic databases were searched, but only a limited attempt to identify unpublished literature was made. Studies available in languages other than English were excluded. It is possible that bias due to publication and language may influence the findings of this review. The identification, extraction and validity assessment of the studies was performed by one reviewer and checked by another, thus reducing the potential for reviewer bias or error. The criteria for assessing the validity of RCTs and CCTs were appropriate. The data extraction was well presented in the report, and the narrative synthesis of the studies was appropriate given the variety of different interventions.

This was a well-conducted systematic review and the authors' conclusions are supported by their findings.

Practice: The authors stated that the provision of increased education may be restricted by a shortage of trained specialist nurses.

Research: The authors stated that there is a need for RCTs with clear designs and explicit hypotheses, with a range of outcomes that are followed up over long time periods. Trials should also focus on the effects of education alone.

NHS R&D Health Technology Assessment (HTA) Programme, project number 01/55/01.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.