Lipid Tolerance Testing in Pregnancy

Objective— Macrosomia in the infant of the well-controlled diabetic mother suggests that a substrate other than glucose may influence fetal growth. We hypothesized that GDM alters lipid homeostasis during pregnancy. Our objective was to determine if an LTT could assist in identification of lipid abnormalities in the GDM individual. Research Designs and Methods— The LTT consisted of bolus infusion of 1.0 mg/kg 10% Intralipid (Cutter Vitrum, Berkeley, CA) followed by measurements of plasma glucose, insulin, glycerol, total triglycerides, and triglyceride fatty acids (18:1 and 18:2), total FFAs, and total phospholipids for 30 min before and 90 min after the bolus. The study groups were composed of 8 nonpregnant, nondiabetic subjects, 8 pregnant, nondiabetic subjects, 8 GDM patients receiving insulin, and 8 GDM patients who were diet controlled. Results— Plasma glucose and plasma insulin concentrations did not change significantly after the bolus. No significant difference was noted in the K 2 for glycerol of the nonpregnant, nondiabetic group compared with the pregnant groups. The K 2 for total triglycerides, plasma triglyceride 18:1, and plasma triglyceride 18:2 indicated increased rates of disappearance of these substrates for the nonpregnant nondiabetic group compared with all pregnant groups. No significant differences were observed among the pregnant groups for any of these parameters. Conclusions— Pregnancy may be associated with a decreased rate of triglyceride lipolysis compared with nonpregnancy. No differences in lipid metabolism were noted among normal pregnant and relatively well-controlled GDM patients.