The aim of this study is to determine the efficacy of oral treatment with glyburide and metformin controlling excessive fetal growth in women with gestational diabetes, using insulin as a ransom on no response to oral treatment .

It is randomized with women who seek care at the Outpatient Diabetes in Pregnancy in our hospital trial Eligible women between 18 - 45anos diagnosed with gestational diabetes , according to the WHO criteria , ratified the public network for prenatal care at the Clinic for Diabetes and Pregnancy HCPA .

Women with singleton pregnancy and gestational age not exceeding 30 weeks at the time of enrollment.

Pregnant women with indication for pharmacological treatment will be invited to randomization to use of oral , glyburide or metformin antidiabetic .

At regular intervals of 2 - 3 weeks fetal growth will be measured with obstetric ultrasonography , until birth.

The primary outcomes will be :

( 1 ) weight and gestational age at birth and the index of large for gestational age fetuses ( ≥ 90th percentile for gestational age ) ( 2 ) the use of insulin to achieve glycemic targets according to fetal growth , as an indirect measure of the inefficiency of oral medications .

The procedures for monitoring metabolic and obstetrical control , assessments of fetal well -being and indications for interruption are usually adopted in the Outpatient Diabetes and Pregnancy of the institution.

- Patients will be followed since their first appointment in our hospital, around the 20th week of pregnancy- until 8 weeks after labor and delivery. That being said, patients will be followed by an average of 28 weeks.

Inclusion Criteria:

• Eligible women between 18-45 years diagnosed with gestational diabetes, according to the WHO criteria (19), ratified the public network for prenatal care at the Clinic for Diabetes and Pregnancy.
• Women with singleton pregnancy and gestational age not exceeding 30 weeks at the time of enrollment, calculated from ultrasound (U.S.) Obstetric performed before the 20th week of pregnancy will be enrolled.

Exclusion Criteria:

• Women who present enrollment in the diagnosis of chronic hypertension, heart disease or chronic lung disease intrauterine restricted or preterm labor, growth, or even chronic diarrhea will be excluded