The recent epidemiological explosion of diabetes amplified the problems regarding the various complications related to the disease and its complex healthcare management. Among these, those relating to the pregnancy of women with diabetes are highly significant from the point of view of social health, for the consequences of the disease on the unborn child, but also in the mother. It is possible that diabetes exists before pregnancy (pregestational diabetes), but much more often it can appear during pregnancy in women unaware of the disease (gestational diabetes). The mainstay of therapy for diabetes and gestational diabetes resides in diet, therapy with oral hypoglycemic agents or insulin, but the appearance on the market of supplements consisting of substances such as D-chiro-Inositol (DCI) arousing considerable interest, as it seems to be able to help in the glycemic control in this type of disease but, of course, its effectiveness must be proved. The data of our study seem to show that the DCI supplement has a role in the regulation of glucose metabolism and insulin sensitivity, and is able to act on the metabolism of pregnant women at risk of developing gestational diabetes, who probably have a basic alteration of insulin and glucose metabolism. It acts improving insulin sensitivity and reducing the onset of gestational diabetes in pregnant women at risk, decreasing the weight gain and nocturnal hypoglycemia responsible for the attacks of hunger at night. Further studies would be desirable to clarify the mechanism of action of DCI at the cellular level in glucose metabolism during pregnancy, and clinical data must be confirmed with wider studies.