OBJECTIVE Prematurity is a known risk factor for hypoglycaemia, hyperglycemia, neonatal sepsis and other common neonatal complications, possibly associated with glucoregolatory hormone (insulin and glucagon) alterations. Insulin and glucagon levels change also in relation to gender, mode of delivery and postnatal clinical severity. Because of the lack of reference range in literature, the aim of this study is to assess plasma insulin and glucagon levels in preterm appropriate for gestational age (AGA) infants of birth weight <1500 g (very low birth weight, VLBW) as a function of gestation, birth weight, gender and mode delivery. METHODS The authors examined 48 preterm AGA infants (mean birth weight 1 163+/-286 g, mean gestational age 28.2+/-2.4 weeks). The infant population was subdivided in relation to gestational age, weight, gender, mode of delivery and assisted ventilation at 5-7(th) days. Plasma glucose, insulin and glucagon levels were assessed in all newborns at birth and at 5-7(th) days of life. Data were analyzed using t-test. RESULTS A negative correlation between insulin and gestational age was observed (P<0.05). At birth, no significant differences regarding plasma glucose, insulin and glucagon levels were observed as a function of the examined category variables. At the 5-7(th) days of life, insulin levels were significantly higher in newborns with gestational age =or<27 weeks (P<0.02), in the female gender (P<0.02) and in the infants born to emergency Cesarean delivery (P<0.05). CONCLUSIONS These findings indicate potentially useful reference range values for plasma insulin and glucagon in the VLBW population.