We plan to test the hypotheses that elevated plasma FFA concentrations are, at least in part, responsible for (1) peripheral (muscle) insulin resistance, elevated hepatic glycose production (HGP) and increased insulin secretion rates (ISR) in pregnancy and (2) we further hypothesize that FFA mediated increases in HGP are compensated for to a large extent by increased ISR in normal pregnant women, but that in women who develop GDM, FFA stimulated ISR is compromised, resulting in increased HGP and fasting hyperglycemia.