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

Abstract

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.