Background: The prevalence of diabetes is on the rise worldwide, and recent studies have suggested that exposure to organochlorine pesticides (OCPs) may contribute to this development. However, the evidence remains inconclusive. Our study aimed to consolidate the existing evidence to understand better the association between OCP exposure and the risk of gestational diabetes mellitus (GDM) and type 2 diabetes (T2D). Methods: We searched for longitudinal and cross-sectional studies in PubMed, Web of Science, and Google Scholar until April 1st, 2023. We included peer-reviewed, English-language studies focused on the general population with clearly stated exposure and outcome measures related to OCP, GDM, and T2D. We collected data on study type, sample size, covariates, and effect measures. The National Toxicology Program’s Office of Health Assessment and Translation approach was used to ensure the study quality. Results: We identified 33 studies, including 8 cohorts, 7 nested case-control, and 18 cross-sectional studies. The focus was mainly on p,p’-DDE, and p,p’-DDT exposures. Findings on the association between OCPs and GDM or T2D risks were mixed, with no conclusive evidence across the studies. For p,p’-DDT, and p,p’-DDE, GDM studies found no significant associations, while T2D studies showed non-significant and positive associations. Other OCP exposures showed mixed results for GDM and T2D. The majority of studies had a probably low risk of bias. Conclusions: The association between OCP exposure and diabetes risk is inconclusive. Differences in study design, exposure assessment methods, and statistical approaches may contribute to inconsistent findings. Further research, including well-designed prospective studies and meta-analyses, is required. We must prioritize alternative pest control, raise awareness of OCP dangers, enforce regulations, and screen at-risk populations. OCP levels monitoring and healthcare guidance for high-exposure populations are also crucial. Key messages: - Inconclusive evidence on the association between OCP exposure and the risk of GDM and T2D calls for further research, including prospective studies and meta-analyses. - Prioritizing OCP risk reduction, raising awareness, and at-risk populations are critical to protect public health.