Glyburide and Metformin for Gestational Diabetes Mellitus (GDM)

Inclusion Criteria: Gestational Diabetes Subject Selection 1. Pregnant women (singleton pregnancy) 2. Gestational diabetes mellitus 3. Able to give written informed consent 4. Drug treatment is required for GDM 5. Gestational age 20-32 weeks * Gestational diabetes diagnosis must occur after 20 weeks and prior to 32 weeks gestation * Randomization and treatment initiation must occur no later than 32 weeks gestation 6. Willing to avoid ethanol 7. 18-45 years of age Type 2 Diabetes Mellitus Subject Selection 1. Able to give written informed consent 2. New diagnosis of type 2 diabetes mellitus 3. Plan to receive metformin for treatment of type 2 diabetes mellitus 4. 18-45 years of age 5. Female 6. Negative pregnancy test 7. Hemoglobin A1C \> 7% Healthy Pregnant Women 1. Able to give written informed consent 2. Pregnant women (singleton) 3. Normal 1-hour glucose tolerance test 4. 20-32 weeks gestation 5. 18-45 years of age Neonates: All the infants of the pregnant women participating in this study will be included Exclusion Criteria: Women with GDM and T2DM 1. Women taking medications expected to interact with glyburide, metformin or alter blood glucose concentrations 2. Serum creatinine \> 1.2 mg/dL 3. Hematocrit \< 28% 4. Allergy to glyburide, metformin or sulfa 5. Significant hepatic disease 6. Congestive heart failure or history of MI 7. Moderate to severe pulmonary disease 8. Adrenal or pituitary insufficiency Healthy Pregnant Women 1. Receiving any hypoglycemic agents 2. Receiving corticosteroids 3. Known kidney, liver, heart, pulmonary, adrenal or pituitary disease 4. Hematocrit \< 28% Neonates 1. Infants that are not viable or too ill for blood sample collection will be included for clinical outcomes data collection, but will be excluded from other research activities. 2. Infants \< 1.5 kg will be included for clinical outcomes data collection, but will be excluded from blood sample collection.