Impact of Insulin Resistance on Insulin-Like Growth Factor-1/Insulin Like Growth Factor-Binding Protein-3 Axis and on Early Weight Gain in Small for Gestational Age Infants

OBJECTIVE: To assess insulin-like growth factor-1 (IGF-1)/IGF-binding protein-3 (IGFBP-3) axis and insulin resistance (IR) and the relationship of these parameters with growth in appropriate for gestational age (AGA) and small for gestational age (SGA) infants at birth and in early infancy. METHODS: Postnatal blood samples for measurement of glucose, insulin, IGF-1, and IGFBP-3 were taken from 60 infants (30 AGA and 30 SGA) at birth and at one, three, and six months of age. Both SGA and AGA infants were divided into two groups: growing well and not growing well. Blood glucose, insulin, IGF-1, and IGFBP-3 values were assessed in all infants. RESULTS: Homeostasis model assessment-IR (HOMA-IR) values in well-growing SGA infants in the third and sixth months were found to be higher than in not well-growing SGA infants (3.9±0.8 vs. 1.0±0.3 at 3 months and 3.3±0.9 vs. 2.4±0.9 at 6 months, p<0.05). IGF-1 levels in well-growing SGA infants at 3 and 6 months were found to be higher than those in not well-growing SGA infants (83.80±44.50 vs. 73.50±17.60 ng/mL at 3 months and 95.12±50.74 vs. 87.67±22.91 ng/mL at 6 months, p<0.05). The IGF-1 values were significantly lower in well-growing SGA infants than in well-growing AGA infants (83.80±44.50 vs. 103.31±30.81 ng/mL at 3 months and 95.12±50.74 vs. 110.87±26.44 ng/mL at 6 months, p<0.05). CONCLUSIONS: This study demonstrates the effects of accelerated early infant growth on IGF-1/IGFBP-3 axis in SGA-born infants.