ABSTRACT Objective: The effect of diabetes during pregnancy on the cognitive development of offspring is unclear because of inconsistent findings from limited studies. This systematic review aims to provide the best available scientific evidence on the associations between maternal pregnancy diabetes and the cognitive development of offspring. Methods: A search was conducted in the EMBASE, CINAHL, PUBMED, PSYCINFO and SCOPUS databases. Studies addressing offspringâ€™s (â‰¤ 12 years) cognitive development as outcome and any diabetes in pregnancy as an exposure were included. Data were extracted and evaluated for quality by two independent reviewers. Results: Fourteen articles were eligible for the review. Ten studies investigated the associations between maternal pre-gestational diabetes mellitus (PDM) or both PDM and gestational diabetes mellitus (GDM) and offspringâ€™s cognitive development; six found at least one negative association. Four studies exclusively examined the relationships between GDM and offspringâ€™s cognitive development; two of them found negative, one positive and one null associations. The use of diverse cognitive and diabetes assessment tools/criteria, and statistical power contributed to the inconsistent findings. Conclusions: Although there are a scarcity of data available on the associations between maternal diabetes in pregnancy and offspringâ€™s cognitive development, this review has found that maternal diabetes during pregnancy appears to be negatively associated with offspringâ€™s cognitive development. Large prospective studies which address potential confounders are needed to confirm the independent effect of maternal diabetes during pregnancy. Keywords: diabetes during pregnancy, gestational diabetes mellitus, child development, systematic review. Key messages: 1. Diabetes during pregnancy appears to be negatively associated with offspringâ€™s cognitive development. 2. The associations between maternal gestational diabetes and childhood cognitive development is scarce; when it exists findings are conflicting. 3. Large prospective studies which address potential confounders are urgently needed to confirm the effect of gestational diabetes. "