Association of serum free IGF-1 and IGFBP-1 with insulin sensitivity in impaired glucose tolerance (IGT)

Aim and Background: Free IGF-1 and IGFBP-1 are associated with obesity which is one of the major features of insulin resistance. But very few studies exist on free IGF-1 and IGFBP-1 in IGT subjects. The present study was undertaken to investigate the association of free IGF-1 and IGFBP-1 with insulin sensitivity in IGT subjects. Subjects and Methods: Ninety-one subjects with impaired glucose tolerance (IGT) were studied along with age- sex- and BMI-matched sixty-one healthy Controls without family history of diabetes or prediabetes. Insulin, free IGF-1 and IGFBP-1 were measured by standard ELISA method. Insulin secretory capacity (HOMA B) and insulin sensitivity (HOMA S) were calculated using fasting glucose and fasting insulin by HOMA-CIGMA software. Results: Fasting free IGF-1 and IGFBP-1 levels were not significantly different among the study groups. In stepwise multiple regression analysis, when free IGF-1 was considered as a dependent variable with other independent variables, model 1 (β = −0.352, p = 0.03), model 2 (β = −0.355, p = 0.033) and model 5 (β = −0.378, p = 0.026) have shown significant association of fasting glucose with free IGF-1. Similarly when IGFBP-1 was considered as a dependent variable, model 4 (β = −0.865, p = 0.03) and model 5 (β = −0.1.07, p = 0.004) have shown negative association of fasting glucose with IGFBP-1. In this analysis model 5 have also shown negative association of HOMA S with IGFBP-1 (β = −1.015, p = 0.017). Conclusion: IGF1 and IGFBP-1 seems to be negatively associated with fasting glucose in IGT subjects and insulin sensitivity (HOMA S) may also be negatively associated with IGFBP-1 in IGT subjects.