By the 12^th week of gestation, mean whole blood and plasma carnitine levels are already significantly ( / p<0.01) lower than those of controls, with a further significant ( / p<0.01) decrease up to parturition. Diminished carnitine levels may cause a downregulation of carnitine palmitoyltransferase1 (CPT1), both the liver isoform (CPT1A) and muscle isoform (CPT1B), carnitine palmitoyltransferase2 (CPT2), and carnitine acetyltransferase (CRAT) in white blood cells of pregnant women, as determined by real time PCR using the LightCyclerSYBR Green technology.

/ L-Carnitine- / L-tartrate supplementation of 2鈥塯/d resulted in an up to 10-fold increase of the relative mRNA abundances of CPT1B, CPT2, and OCTN2 and a 5-fold increase of CPT1A, and CRAT.

There is a relationship between the relative mRNA levels of CPT1A and CPT1B and the FFA plasma levels. The substitution of 2鈥塯 / L-carnitine- / L-tartrate/d resulted in significant ( / p<0.001) lower FFA levels compared to untreated controls and the groups substituted with 0.5 and 1鈥塯 / L-carnitine/d although plasma carnitine levels were not significantly increased. The most substantial effect was the reduced portion of acylcarnitines on total carnitine in those women receiving 2鈥塯 / L-carnitine- / L-tartrate.

Carnitine substitution resulted in an enhanced excretion of both, free carnitine and acylcarnitines, whereas acetylcarnitine accounts for 50鈥?5% of total acylcarnitines.

The results of the present study provide evidence that / L-carnitine supplementation in pregnancy in sufficient doses avoids a striking increase of plasma FFAs, which are thought to be the main cause of insulin resistance and consequently gestational diabetes mellitus (GDM).