IGF2 and Hypoglycemia: Hypoglycemia in IGF-II-producing NICTH is thought to be caused by an increase in tumor-derived free big IGF-II, and the big IGF-II is present in the blood as a binary complex of IGF-IGF binding protein that does not form an IGF-II ternary complex and can easily pass through the capillary wall to the cell surface receptor [7].