Review of review-level evidence to inform the development of NICE public health guidance for the prevention of pre-diabetes among adults in high-risk groups

This report presents the findings of a systematic review of review-level evidence concerning the prevention of pre-diabetes (raised and impaired glucose levels) in populations/groups at higher risk (black and minority ethnic [BME] or low socioeconomic status [SES]) using community- and population-level interventions. The primary research question for the review was: What is known from review-level evidence about the effectiveness and costeffectiveness of population- and community-level interventions to improve modifiable risk factors associated with pre-diabetes and type 2 diabetes among BME and low-income / low-SES groups? The secondary research questions were: What is known about promising ways to tailor interventions for diabetes risk factors to BME or low-income groups, for outcomes including improved BMI, physical activity levels, and blood pressure? What are the barriers/facilitators to the effectiveness of interventions?

Overall, we found insufficient evidence to draw strong conclusions to the three review questions: From the evidence base identified, we can determine little from review-level evidence about the effectiveness and cost-effectiveness of population- and community-level interventions to improve modifiable risk factors associated with pre-diabetes among BME and low-income / low-SES groups. This is partly due to the generally low-quality evidence reviews in this field and to the lack of evidence on BME/low SES groups other than African American populations. However, some promising directions for practice are highlighted below. There is some evidence that tailoring interventions for diabetes risk factors to BME or low-SES groups can improve outcomes including BMI, physical activity levels, and blood pressure. However, this is inconsistent both within and across reviews, and predominantly focused on cultural adaptations for African American samples. There are likely to be numerous barriers and facilitators to the effectiveness of interventions. Unfortunately, there is insufficient review-level evidence on the effects of intervention administrators, barriers to retention of participants in primary studies in the reviews, and the effects of evaluation design, to draw any definitive conclusions. Some promising messages emerged from the evidence for practice. These are: Multi-component interventions (e.g., those that target both physical activity and dietary habits) are likely to generate better outcomes than single-component interventions. Interventions often attempt to be culturally sensitive, such as using members of the target community to deliver the intervention. For some individuals, this will be a respected member of the community (e.g., a religious leader), but this is not necessarily the case. However, the reviews rarely reported whether such techniques were effective at recruiting and retaining participants, and so it is unclear whether tailoring is effective. Nonetheless, in the absence of evidence to the contrary, it would seem sensible to consider cultural adaptations as a way to recruit and retain participants. A range of methods needs to be used to increase accessibility to the intervention, which might include innovative approaches such as television and workplace programmes. Strategies to promote individual motivation to change and family/ friend support for the programme are likely to be important factors promoting success for many people.