Gestational diabetes mellitus takes place in 2 steps. First, it is the consequence of insulin resistance due to the modifications of the pregnancy hormonal environment, and second, of the deficiency of the beta cells of the pancreas to respond by a sufficient insulin secretion. This physiopathology is closely connected to the one of type 2 diabetes. Insulin, indeed, can remedy these 2 etiologies, but it is logical to think about using oral hypoglycemic agents which have been created to treat them: they are a natural choice because they improve insulin sensitivity (metformin, a biguanide) or insulin secretion (glyburide, a sulfonylurea). It also seems natural to use them in combination, glyburide being added to metformin if needed.