INS and colorectal cancer: Exogenous hyperinsulinemia induced by insulin therapy is prevalent in T1DM patients and may be an important factor promoting growth of colonic epithelial cells43 via direct activation of insulin receptor or insulin-like growth factor (IGF)-I receptor and inhibition of IGF binding protein.44 Elevated levels of C-peptide, a marker of insulin secretion, have been found to be related to increased risk of colorectal cancer in many studies.5,6 Further, chronic insulin therapy was reported to be associated with an increased risk of colorectal adenoma and carcinoma.45