Background: Gestational diabetes mellitus is a form of diabetes whose prevalence is constantly increasing, thus leading to a growth in the necessary resources and organization of diabetes and obstetric facilities. The literature suggests that adherence to diet and therapy in patients with GDM might be highly variable and only sometimes optimal, and that this suboptimal compliance might be associated with more complicated treatment management or some adverse perinatal outcomes. This study evaluates this adherence and the benefits of constant blood glucose monitoring regarding maternalneonatal complications. Methods: We conducted a multicentre prospective observational study, including all patients diagnosed with gestational diabetes mellitus and aged ≥ 18 years, between January 2019 and November 2021. We measured patients' adherence by clinical diary monitoring (medical evaluation) and observation of data obtained from glycaemic control (glucometer analysis). Patients were divided into three groups the adherent patient group, the non-adherent patient group and the partially adherent patient group; then, we compared the groups to assess the impact of non-adherence on patients' health. Results: 122 (46.9 %) were classified in the adherent group (AG), 91 (35.0 %) in the partially adherent group (PG), and 47 (18.1 %) in the non-adherent group (NG) out of a population of 260 patients. The AG and PG groups were associated with a RRR of 74 % (95 % CI:0.13-1.03, p = 0.057) and 32 % (95 % CI:0.25-1.84, p = 0449) in operative delivery, respectively. Finally, this study proved that full or partial adherence is associated with decreased insulin administration during labour in 67 % (OR=0.33 p = 0.038). Conclusion: The study showed that patients' adherence to diet and/or therapy proposed by the diabetologist could significantly influence optimal glycaemic control during pregnancy Better compliance may lead to a lower incidence of operative deliveries and insulin utilization during pregnancy and labour.
