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.

OUR GENERAL RESEARCH HYPOTHESIS IS THAT: in pregnant women with gestational diabetes mellitus, using both oral hypoglycemic agents (glyburide added to metformin if needed) allows a glycemic control comparable to the one obtained with insulin, but with a better acceptability from women and a better health status, diabetes treatment satisfaction and well-being and a reduced postnatal depression.

Inclusion Criteria:

• women,
• age ≥ 18 yrs,
• with gestational diabetes at 24-28 weeks (Canadian Diabetes Association (CDA) criteria),
• who need a pharmacological treatment following the failure of the diet and exercise,
• to understand and read French or English.

Exclusion Criteria:

• known type 1 or type 2 diabetes,
• treatment interfering with glucose metabolism,
• allergies to one of the components of the treatment,
• hepatic or hematologic diseases.