Inclusion Criteria:

• Fifteen women with GDM and 15 women without GDM will be recruited through the Mayo Clinic Obstetric Practice in Rochester, Minnesota in the third trimester of pregnancy.
• The screening visit will be scheduled from 2-12 weeks postpartum.
• Gestational diabetes will be diagnosed based on Carpenter and Coustan criteria when at least two of the following four plasma glucose concentrations [measured fasting and 1h, 2h and 3h during 100g oral glucose tolerance testing)(OGTT)] are met or exceeded:
  • fasting 95mg/dL (5.3mmol/L);
  • 1h 180mg/dL (10.0mmol/L);
  • 2h 155mg/dL (8.6mmol/L); and
  • 3h 140mg/dL (7.8mmol/L).
• Women will be characterized as having normal glucose tolerance if they do not meet or exceed two or more of the aforementioned values on OGTT. These women will have previously failed a 50g glucose challenge [1 hr glucose >= 140mg/dL (7.8mmol/L).
• We will also characterize women as having normal glucose metabolism if they passed a 50g glucose challenge in pregnancy [1 hr glucose <140mg/dL (7.8mmol/L)] and did not proceed to further glucose testing during the pregnancy.

Exclusion Criteria:

• Women < 20 years of age or > 40 years of age will not be studied to minimize the potential confounding effects of extremes of age on glucose absorption and metabolism.
• Known active systemic illness.
• Women in which the index pregnancy was a multiple pregnancy.
• Women with an HbA1c of ≥ 5.7% (39mmol/mol) in early pregnancy or a history of diabetes.
• Prior therapy with an anti-diabetic medication, or a medication that could affect glucose metabolism.
• History of abdominal surgery (other than appendectomy, cholecystectomy or tubal ligation).