Association of serum free IGF-1 and IGFBP-1 with insulin sensitivity and insulin secretory defects in Bangladeshi type 2 diabetes mellitus

ABSTRACT

Serum free insulin like growth factors-1 [IGF-1] and insulin like growth factor binding protein-1 [IGFBP-1] may have an association with insulin resistance and B-cell secretory dysfunction. Present study is undertaken to explore the independent association of IGF-1 and IGFBP-1with two basic defects in type 2 diabetic patients in a Bangladeshi population. Sixty eight type 2 diabetes mellitus [DM] subjects are studied along with age-, sex- and BMI-matched 61 healthy controls without family history of diabetes or prediabetes. Insulin, free IGF-1 and IGFBP-1 are measured by the standard ELISA method. Insulin secretory capacity [HOMA B] and insulin sensitivity [HOMA S] are calculated using fasting glucose and fasting insulin by HOMA-CIGMA software. Fasting free IGF-1 and IGFBP-1 levels are not significantly different between the study groups. But the level of free IGF-1 is significantly higher [p = 0.03] in type 2 DM subjects compared to controls in the low BMI group [BMI regression analysis, positive association of HOMA B with free IGF-1 is evident. Similarly positive association of HOMA B and HOMA S with IGFBP-1 is shown in different models. In the same analysis, both free IGF-1 and IGFBP-1 are inversely associated with fasting insulin in different models of stepwise multiple regression analysis. Both IGF-1 and IGFBP-1 are negatively associated with fasting insulin levels. Moreover B-cell secretory dysfunction is positively associated with IGF-1 and both B-cell secretory dysfunction and insulin sensitivity are also positively associated with IGFBP-1 in type 2 diabetic patients