Gut microbiota regulates many processes occurring in the intestine, affecting its immune and endocrine functions, the absorption of substances. There is a hypothesis that intestinal dysbiosis plays a role in the pathogenesis of gestational diabetes mellitus (GDM). The paper reviews the data available in the literature of the world’s leading reference bases (MEDLINE, EMBASE, Cochrane) on changes in the microbiota and microbiome in women with GDM. An analysis of the findings has revealed numerous correlations between specific bacterial taxa and changes in the metabolic process in the body during pregnancy. The possible mechanism for the development of GDM is the occurrence of inflammation in the intestinal wall in the presence of gut dysbiosis, which results in barrier dysfunction of enterocytes and in an increase in their permeability and endotoxemia. This leads to overexpression of proinflammatory cytokines and increased insulin resistance. The use of probiotics is a method to correct gut dysbiosis. The administration of probiotics is shown to reduce subclinical inflammatory responses and to restore the balance of absorbed substances. It is probable that this method may also be relevant to the therapy of hyperglycemic states during pregnancy.