Postnatal changes in concentrations of free and bound leptin.

AIM To evaluate the effect of maternal diabetes on the concentrations of free and bound leptin at birth and during postnatal adaptation. METHODS Total, bound, and free leptin concentrations and the percentage of free leptin were measured in cord plasma and plasma at 3 days of age of 13 term infants of mothers with gestational diabetes mellitus (GDM) and 13 term infants of healthy mothers. Gestational age was 40.2 (1.4) weeks, and birth weight was 3693 (549) g (means (SD)). RESULTS At birth, infants of mothers with GDM had significantly higher concentrations of total, bound, and free leptin and a higher percentage of free leptin (all p < 0.05). In all infants, these concentrations were significantly lower at 3 days of age than at birth (all p < 0.003), and the differences in concentrations of total, bound, and free leptin between the two groups were no longer significant. In infants of mothers with GDM, the percentage of free leptin remained unchanged, and was higher (p<0.05) than in infants of healthy mothers; in the latter group the percentage of free leptin significantly declined (p = 0.02). CONCLUSIONS GDM appears to influence fetoplacental leptin metabolism. This effect may be mediated through altered maternal glucose metabolism, or insulinaemia, or both.