ABSTRACT Objective To compare the major outcomes of use of metformin and glyburide in treatment of gestational diabetes mellitus. Methods Studies published in English, in the last 10 years, in the databases MEDLINE®, SciELO, LILACS and Cochrane Library were analyzed, and randomized controlled trials were selected. Health Sciences Descriptors were used to compose the search phrase, and the keywords "Gestational diabetes", "Glyburide", "Metformin" and their variations were searched in the Medical Subject Headings. PRISMA systematization was used to prepare this review, and a meta-analysis was conducted aiming to mathematically show the results of fasting blood glucose, postprandial blood glucose, birth weight and weight gain during pregnancy after using metformin and glyburide. Results The studies evaluated birth weight, neonatal hypoglycemia, mode of delivery, need for intensive care, Apgar score, macrosomia, fasting glucose, postprandial glucose and weight gain during pregnancy. In 60% of studies, there were no statistically significant differences regarding safety and efficacy of administration of metformin and glyburide. Meta-analysis demonstrated the absence of statistical differences between these drugs in fasting blood glucose (p=0.821), postprandial blood glucose (p=0.217) and birth weight (p=0.194). However, significant differences were shown in weight gain during pregnancy (p=0.036). Conclusion The methods are effective, but the adverse effects of glyburide are more common; therefore, the use of metformin should be recommended, if in monotherapy.