In a study published in the journal BMJ Open, we reviewed the clinical outcomes of combined diet and physical activity interventions for people at high risk of type 2 diabetes. We looked at combined diet and physical activity interventions including ≥2 interactions with a healthcare professional, and ≥12 months follow-up. Our primary outcome measures included glycaemia, diabetes incidence. Secondary outcomes included behaviour change, measures of adiposity, vascular disease and mortality.
We identified 19 recent reviews for inclusion in our study. Most reviews reported that interventions were associated with net reductions in diabetes incidence, measures of glycaemia and adiposity. Small effect sizes and potentially transient effect were reported in some studies, and some reviewers noted that durability of intervention impact was potentially sensitive to duration of intervention and adherence to behaviour change. Behaviour change, vascular disease and mortality outcome data were infrequently reported, and evidence of the impact of intervention on these outcomes was minimal. Evidence for age effect was mixed, and sex and ethnicity effect were little considered.
We concluded that relatively long-duration lifestyle interventions can limit or delay progression to diabetes under trial conditions. However, outcomes from more time-limited interventions, and those applied in routine clinical settings, are more variable, in keeping with the findings of recent pragmatic trials. There is little evidence of intervention impact on vascular outcomes or mortality end points in any context. Hence, ‘real-world’ implementation of lifestyle interventions for diabetes prevention may be expected to lead to modest outcomes.
We identified 19 recent reviews for inclusion in our study. Most reviews reported that interventions were associated with net reductions in diabetes incidence, measures of glycaemia and adiposity. Small effect sizes and potentially transient effect were reported in some studies, and some reviewers noted that durability of intervention impact was potentially sensitive to duration of intervention and adherence to behaviour change. Behaviour change, vascular disease and mortality outcome data were infrequently reported, and evidence of the impact of intervention on these outcomes was minimal. Evidence for age effect was mixed, and sex and ethnicity effect were little considered.
We concluded that relatively long-duration lifestyle interventions can limit or delay progression to diabetes under trial conditions. However, outcomes from more time-limited interventions, and those applied in routine clinical settings, are more variable, in keeping with the findings of recent pragmatic trials. There is little evidence of intervention impact on vascular outcomes or mortality end points in any context. Hence, ‘real-world’ implementation of lifestyle interventions for diabetes prevention may be expected to lead to modest outcomes.
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