CONTEXT: The effect of diabetes during pregnancy on the cognitive development of offspring is unclear because of inconsistent findings from limited studies. OBJECTIVE: This review was aimed to provide the best available scientific evidence on the associations between maternal pregnancy diabetes and the cognitive development of offspring. DATA SOURCES: A search was conducted in the Embase, CINAHL, PubMed, PsycINFO, and Scopus databases. STUDY SELECTION: Studies addressing the cognitive development of offspring (aged ≤12 years) as outcome and any diabetes in pregnancy as an exposure were included. DATA EXTRACTION: Data were extracted and evaluated for quality by 2 independent reviewers. RESULTS: Fourteen articles were eligible for the review. Ten studies investigated the associations between maternal pregestational diabetes or both pregestational and gestational diabetes and offspring’s cognitive development; 6 studies found at least 1 negative association. Four studies exclusively examined the relationships between gestational diabetes and offspring’s cognitive development; 2 studies found a negative association, 1 a positive association, and 1 a null association. The use of diverse cognitive and diabetes assessment tools/criteria, as well as statistical power, contributed to the inconsistent findings. LIMITATIONS: The English-language restriction and publication bias in the included studies are potential limitations. CONCLUSIONS: Although there are few data available regarding the associations between maternal pregnancy diabetes and offspring’s cognitive development, this review found that maternal diabetes during pregnancy seems to be negatively associated with offspring’s cognitive development. Large prospective studies that address potential confounders are needed to confirm the independent effect of maternal diabetes during pregnancy.