Introduction: Monogenic diabetes occurs in up to 3% of people with diabetes. Mutations in over 40 different genes are responsible. The most common genes affected are HNF1A, HNF4A, GCK, and HNF1B. Additionally, other types of diabetes with a genetic aetiology include neonatal diabetes and diabetes plus syndrome. Each of these genetic subtypes have a different phenotype and require distinctive treatments. Due to the overlap of monogenic diabetes with type 1 and 2 diabetes and even gestational diabetes, they can often be misdiagnosed. During pregnancy, individual subtypes require treatment that is different from standard diabetes care, so recognition and prompt diagnosis of monogenic diabetes is important to avoid inadequate treatment. Areas covered: We describe the management of monogenic diabetes for the most significant subtypes, focussing on the impact on and management in pregnancy. Conclusion: A genetic diagnosis of diabetes can alter long-term treatment in those with diabetes. In pregnancy and the postnatal period, this can involve specific management changes determined by the gene affected and whether there is fetal inheritance of the gene. Where inheritance of the genotype influences the outcomes, cell-free fetal testing will hopefully soon become a diagnostic tool for early recognition of fetal mutations.