Relationship between insulin-like growth factor I levels, early insulin treatment, and clinical outcomes of very low birth weight infants.

OBJECTIVES: Insulin regulates the secretion of insulin-like growth factor I (IGF-I) in the newborn, and low levels of IGF-I have been linked to neonatal morbidity. As part of the Neonatal Insulin Replacement Therapy in Europe Trial, we investigated the impact of early insulin treatment on IGF-I levels and their relationship with morbidity and growth. STUDY DESIGN: Prospective cohort analyses of data collected as part of an international randomized controlled trial. Blood samples (days 1, 3, 7, and 28), were taken for IGF-I bioassay from 283 very low birth weight infants (<1500 g). RESULTS: Early insulin treatment led to a late increase in IGF-I levels between day 7 and 28 (P = .028). In the first week of life IGF-I levels were lower in infants with early hyperglycemia; mean difference -0.10 µg/L (95% CI -0.19, -0.02, P = .02). Lower levels of IGF-I at day 28 were independently associated with an increased risk of chronic lung disease, OR 3.23 (95% CI, 1.09-9.10), and greater IGF-I levels were independently associated with better weight gain, 0.10 kg (95% CI, 0.03-0.33, P = .02). CONCLUSIONS: Early intervention with insulin is related to increased IGF-I levels at 28 days. Low IGF-I levels are associated with hyperglycemia, increased morbidity, and reduced growth. Increasing IGF-I levels may improve outcomes of very low birth weight infants.

Prevalence and determinants of hyperglycemia in very low birth weight infants: cohort analyses of the NIRTURE study.

OBJECTIVES: To investigate the prevalence and determinants of hyperglycemia in the preterm population, as part of the Neonatal Insulin Therapy in Europe (NIRTURE) Trial. STUDY DESIGN: We conducted prospective cohort analyses of continuous glucose monitoring data from control infants participating in an international randomized controlled trial. Data were collected from 188 very low birth weight infants (<1500 g). RESULTS: In the first week of life, 80% of infants had evidence of glucose levels >8 mmol/L, and 32% had glucose levels >10 mmol/L >10% of the time. Independent risk factors for hyperglycemia included increasing prematurity, small size at birth, use of inotropes, lipid infusions, and sepsis. There was a lack of association between rate of dextrose infused and risk of hyperglycemia. CONCLUSION: The prevalence of hyperglycemia in the very low birth weight infant is high, with marked variability in prevalence between infants, not simply related to rates of glucose infused, but to other potentially modifiable risk factors.