Infants born to diabetic mothers have elevated cord blood leptin levels. The aim of this study was to investigate whether the situation persists at the 2nd postnatal day, taking the fasting and satiety states into account and the influence of fetal exposure to hyperinsulinemia, which are proven important contributing factors to plasma leptin levels. Twenty infants born to mothers with gestational diabetes (Group I) and 20 controls (Group II) were included in the study. Groups were similar for sex and anthropometric measurements. Group I had higher leptin concentrations compared to Group II in fasting and satiety states (p < 0.01). Fasting state leptin levels were significantly lower than seen in satiety in both groups (p < 0.01). There was a positive and significant correlation between leptin concentrations and body mass index of infants. Leptin concentrations were positively correlated with plasma insulin levels in Group I. These findings suggest that plasma leptin levels are high in both fasting and satiety states on the 2nd postnatal day in infants born to mothers with gestational diabetes. The possible mechanism underlying this condition is fetal exposure to hyperinsulinemia due to hyperglycemia. The uniqueness of this report are that fasting and satiety states were taken into account and that the data was collected from the samples taken on the 2nd postnatal day, thus reflecting the exact milieu of the infant excluding the effects of the mother and the placenta.