A Cochrane review included 11 studies with a total of 1603 subjects. Ten trials provided suitable data for entry into meta-analysis. Glycaemic control (HbA1c), showed an improvement following culturally appropriate health education at three months (WMD - 0.3%, 95% CI -0.6 to -0.01), and at six months (WMD -0.6%, 95% CI -0.9 to -0.4), compared with control groups who received 'usual care'. This effect was not significant at 12 months post intervention (WMD -0.1%, 95% CI -0.4 to 0.2). Knowledge scores also improved in the intervention groups at three months (SMD 0.6, 95% CI 0.4 to 0.7), six months (SMD 0.5, 95% CI 0.3 to 0.7) and twelve months (SMD 0.4, 95% CI 0.1 to 0.6) post intervention. Other outcome measures both clinical (such as lipid levels, and blood pressure) and patient centred (quality of life measures, attitude scores and measures of patient empowerment and self-efficacy) showed no significant improvement compared with control groups.
Comment: The quality of evidence is downgraded by study quality (inadequate or unclear allocation concealment) and by inconsistency (heterogeneity in interventions and outcomes).