Insulin sensitivity in preterm AGA and SGA infants.

1. Premature infants 28-32 weeks gestational age;
2. Presence of a (central) venous and arterial catheter for clinical reasons;
3. For preterm SGA infants: growth retardation caused by placental insufficiency, assessed by maternal history (pregnancy induced hypertension, preeclampsia), and confirmed by Doppler flow measurements of the umbilical arteries (Pulsatility index, PI, >+2 SD for gestational age, measured on two occasions)

1. For preterm SGA infants: growth retardation based on other causes (e.g. congenital infections, congenital malformations);
2. Major congenital malformations;
3. Severe perinatal asphyxia defined as 5 minute Apgar score <7;
4. Severe disturbances of glucose metabolism (glucose intake <4 or >8 mg.kg-1.min-1, or need for insulin therapy to maintain the glucose concentration between 2.6 and 8 mmol/l);
5. Severe respiratory distress. Mild ventilatory support is allowed:
a. nCPAP with maximum FiO2 of 0.40, maximum PEEP 6 cm H2O;
b. SIMV with maximum inspiratory peak pressure of 18 cm H2O and maximum FiO2 of 0.40;
c. HFOV with maximum continuous distending pressure of 12 cm H2O and maximum FiO2 of 0.30;
6. Need of vasopressor support for hypotension;
7. Treatment with systemic corticosteroids;
8. Clinical or laboratory evidence of sepsis: lethargy or irritability, hypo- or hyperthermia, temperature instability, tachypnea, apnea, bradycardia, hypotension, gastric retention, abdominal distension, pallor, elevated CRP-level, leukocytosis or leukocytopenia and increased number of band neutrophils;
9. Low haemoglobin level at the study days with need for a blood transfusion;
10. Positive family history for type 2 diabetes in first degree relatives;
11. No informed consent from parents or legal guardians.