Our hypothesis is that myoinositol and metformin in pregnant women with high-risk factors for glucose intolerance would reduce insulin resistance and consequently lower the incidence of gestational diabetes mellitus (GDM), a metabolic disorder of pregnancy characterized by maternal hyperglycemia due to deficient response to physiological insulin resistance, which may have a negative impact on perinatal outcome and long-term sequelae. In recent years, this pathology has become increasingly important given the global obesity epidemic and the delay in becoming pregnant, especially in industrialized countries. For this reason, the attempt to prevent, rather than cure, gestational diabetes is particularly important. In addition to lifestyle changes (especially diet and doing more exercise), myoinositol and metformin are the most promising factors at the moment, although not all RCTs published so far agree on their real effectiveness. A review of the articles published so far allows us to assume, albeit with some distinctions, that they can play a positive role.