Maternal plasma concentrations of IGF-1, IGFBP-1, and C-peptide in early pregnancy and subsequent risk of gestational diabetes mellitus

Objective Insulin-like growth factor-1 (IGF-1) and IGF binding protein-1 (IGFBP-1) may be important determinants of glucose homeostasis. We examined the association between circulating concentrations of IGF-1, IGFBP-1 in early pregnancy and development of gestational diabetes mellitus (GDM). Study design Maternal plasma (collected at 13 weeks) IGF-1, IGFBP-1, and C-peptide were measured using immunoassay. Relative risks (RR) and 95% CIs were calculated. Results The percentage of the cohort that developed GDM was 5.8% (n = 804). Free IGF-1 and IGFBP-1 were inversely associated with GDM risk, while C-peptide was positively associated with GDM risk (P for trend test < .05). Women with free IGF-1 ≥1.08 ng/mL experienced a 69% reduced risk of GDM (CI 0.12-0.75) compared with women having concentrations <0.80 ng/mL. There was a 57% reduced risk of GDM among women with IGFBP-1 ≥68.64 ng/mL (RR = 0.43, CI 0.18-1.05). Women with C-peptide ≥3.00 ng/mL experienced a 2.28-fold increased risk of GDM (CI 1.00-5.19) compared with women who had concentrations <1.45 ng/mL. Conclusion These associations may help to further elucidate the pathologic process of GDM.