Insulin is an essential hormone for maintaining normal blood glucose. It is the principal regulator of glucose utilization in liver, skeletal muscle, and adipose tissue. Abnormalities of insulin synthesis, secretion, or action can result in hypoglycemia or hyperglycemia, including diabetes mellitus.
Synthesis: Insulin is synthesized from the pancreatic beta cells from a single-chain precursor, preproinsulin. Preproinsulin is cleaved to proinsulin which is further cleaved by proconvertases into three polypeptide chains: alpha, beta, and C-peptide chains. Insulin is formed by linkage of the alpha and beta chains by disulfide bonds. The remaining C-peptide is secreted from the beta cell with insulin in equal molar portions. Insulin and C-peptide levels can be used to evaluate pancreatic function and glucose tolerance (Gardner & Shoback, 2007; Kronenber, Melmed, Polonsky, & Larsen, 2008).
Secretion: Insulin secretion is...
References and Readings
- Gardner, D. G., & Shoback, D. (2007). Greenspan’s basic & clinical endocrinology (8th ed.). New York: McGraw-Hill.Google Scholar
- Kronenber, H., Melmed, S., Polonsky, K., & Larsen, P. R. (2008). Williams textbook of endocrinology (11th ed.). Philadelphia: Saunders Elsevier.Google Scholar
- Lifshitz, F. (2007). Pediatric endocrinology (5th ed.). New York: Informa Healthcare.Google Scholar
- Sperling, M. (2008). Pediatric endocrinology (3rd ed.). Philadelphia: Suanders Elsevier.Google Scholar