Circulating IGF1 and IGFBP3 in relation to the development of β-cell autoimmunity in young children.

OBJECTIVE

This study aimed at investigating the role of IGF1 and IGF binding protein 3 (IGFBP3) in the development of β-cell autoimmunity.

METHODS

Five hundred and sixty-three subjects with HLA-conferred susceptibility to type 1 diabetes (T1D) were monitored for signs of seroconversion to positivity for insulin and/or GAD, IA2, and zinc transporter 8 autoantibodies by the age of 3 years. In 40 subjects who developed at least one autoantibody, IGF1 and IGFBP3 plasma concentrations were measured and compared with 80 control subjects who remained negative for autoantibodies, and were matched for age, sex, country of origin, and HLA genotype. The increments of IGF1, IGFBP3, and IGF1/IGFBP3 molar ratio before and after seroconverison were compared with corresponding time intervals in controls.

RESULTS

The IGF1 concentrations at the age of 12 months and the IGF1/IGFBP3 ratio at the age of 24 months were lower in the autoantibody-positive children (P<0.05). The increase in circulating IGFBP3 was significantly higher in the autoantibody-positive children before seroconversion than in the corresponding time intervals in controls (0.43 mg/l; 95% CI 0.29-0.56 vs 0.22 mg/l; 95% CI 0.10-0.34 mg/l; P<0.01). Children carrying the high-risk HLA genotype had lower plasma IGF1 and IGFBP3 concentrations at the age of 24 months than those with low-risk genotypes (P<0.05 and < 0.01 respectively).

CONCLUSIONS

Circulating IGF1 and IGFBP3 appear to have a role in early development of β-cell autoimmunity. The decreased IGF1 concentrations in children with the high-risk HLA genotype may contribute to the reduced growth previously described in such children.