Cancer Outcomes Among Prediabetes and Type 2 Diabetes Populations With Dietary and Physical Activity–based Lifestyle Interventions

Abstract Context People with type 2 diabetes (T2D) have higher risks of cancer incidence and death. Objective We aimed to evaluate the relationship between dietary and physical activity–based lifestyle intervention and cancer outcomes among prediabetes and T2D populations. Methods We searched for randomized controlled trials with at least 24 months of lifestyle interventions in prediabetes or T2D populations. Data were extracted by pairs of reviewers and discrepancies were resolved by consensus. Descriptive syntheses were performed, and the risk of bias was assessed. Relative risks (RRs) and 95% CIs were estimated using a pairwise meta-analysis with both a random-effects model and a general linear mixed model (GLMM). Certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation framework, and trial sequential analysis (TSA) was conducted to assess if current information is enough for definitive conclusions. Subgroup analysis was performed by glycemic status. Results Six clinical trials were included. Among 12 841 participants, the combined RR for cancer mortality comparing lifestyle interventions with usual care was 0.94 (95% CI, 0.81-1.10 using GLMM and 0.82-1.09 using random-effects model). Most studies had a low risk of bias, and the certainty of evidence was moderate. TSA showed that the cumulative Z curve reached futility boundary while total number did not reach detection boundary. Conclusion Based on the limited data available, dietary and physical activity–based lifestyle interventions had no superiority to usual care on reducing cancer risk in populations with prediabetes and T2D. Lifestyle interventions focused on cancer outcomes should be tested to better explore their effects.