The Association of Dietary Diabetes Risk Reduction Score and the Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies

Background/Objectives: Several studies have suggested a contrasting link between a diabetes risk reduction diet (DRRD) pattern and cancer risk; however, their findings have been inconsistent. This study aims to systematically review observational studies and, where possible, quantify the overall effect through a meta-analysis. Methods: Searches were conducted in PubMed, Scopus, and Web of Science through May 2025. Odds ratios (ORs), along with their confidence intervals, were extracted for meta-analysis. The random-effects model was used to combine the ORs. Results: Nineteen studies met the inclusion criteria for the systematic review and meta-analysis. Of these, six reports examined the relationship between the DRRD and breast cancer risk, three assessed liver cancer incidence, two analyzed pancreatic cancer risk, and two focused on endometrial cancer. Additionally, seven studies explored the association with other cancers, including ovarian, colorectal, renal, head and neck, bladder, and lung cancers. The meta-analysis revealed that high adherence to the DRRD is associated with a decreased cancer risk (OR = 0.77, 95% confidence interval 95% CI: 0.71–0.84, p < 0.001). Conclusions: After stratifying by geographic region, gender, study design, and cancer site, the inverse relationship remained significant across all subgroups. DRRD can be viewed as a beneficial approach associated with a lower cancer risk.