Diabetes, Vol 48, Issue 4 834-838, Copyright © 1999 by American Diabetes Association
Effect of insulin on fat metabolism during and after normal pregnancy
E Sivan, CJ Homko, X Chen, EA Reece and G Boden
Department of Obstetrics and Gynecology, Temple University Hospital, Philadelphia, Pennsylvania 19140, USA.
Whereas development of resistance to the action of insulin on glucose
metabolism during gestation has been recognized, it is presently not known
whether there is also resistance to the action of insulin on lipid
metabolism. We have, therefore, examined the effect of physiological
hyperinsulinemia (during euglycemic-hyperinsulinemic clamping) on free
fatty acid (FFA) turnover in seven nondiabetic overweight or obese women
during and after pregnancy. Basal rates of FFA release, oxidation, and
reesterification and basal plasma FFA concentrations were not significantly
different from each other during the 2nd and 3rd trimester of pregnancy and
postpartum. During euglycemic-hyperinsulinemic (approximately 500 pmol/l)
clamping, however, lipolysis was significantly less inhibited during the
3rd trimester (from 7.0 +/- 0.9 to 4.9 +/- 0.9 micromol x kg(-1) x min(-1),
-30%) than during the 2nd trimester (from 8.4 +/- 0.6 to 4.1 +/- 0.9
micromol x kg(-1) x min(-1), -51%) and postpartum (from 8.5 +/- 1.1 to 4.2
+/- 0.6 micromol x kg(-1) x min(-1), -51%). Similarly, fat oxidation was
not inhibited at all (from 3.5 +/- 0.3 to 3.8 +/- 0.5 micromol x kg(-1) x
min(-1)) during the 3rd trimester but was suppressed by 51% (from 3.9 +/-
0.2 to 1.9 +/- 0.3 micromol x kg(-1) x min(-1)) during the 2nd trimester
and by 38% (from 2.6 +/- 0.7 to 1.6 +/- 0.5 micromol x kg(-1) x min(-1)
postpartum. These data demonstrated that resistance to the action of
insulin on lipolysis and on fat oxidation developed during late gestation
and disappeared postpartum.