June 18, 2019
Properties and mechanism of action
Insulin is a hormone secreted by the pancreas and composed of two peptide chains. It regulates the sugar metabolism in the body. The effects of insulin are mediated through the insulin receptors located in the cell membranes of the liver, muscle tissue and adipose tissue.
Insulin increases the production of glycogen (i.e. the formation of the sugar stored in the body), promotes glucose and amino acids intake into cells, accelerates protein synthesis, and decreases the protein breakdown. Thus, insulin is anabolic, meaning that it is a tissue-growing hormone. The anabolic effect of insulin has been known since the first time it began to be used in the treatment of diabetes. Insulin may also have an indirect slimming effect as a result of its effect of diminishing the appetite and increasing energy consumption. However, insulin causes lipogenesis, which increases fat mass and body weight [1, 2].
Insulin made by recombinant DNA-technology is used for diabetes treatment by subcutaneous injections. Medical insulins are insulin derivatives that are developed to have an effect either quickly or slowly. Through derivatives of varying strengths and durations of action, the sugar balance of diabetics can be regulated individually for each person.
Insulin is used for doping purposes especially after resistance training to enhance the PI3K/Akt signalling pathway because insulin sensitivity is increased after practice. This aims to improve recovery and the anabolic effect. Insulin is also used for the self-treatment of elevated blood sugar induced by anabolic androgenic steroids and the growth hormone. Typically, short-acting (i.e. fast-acting) insulin is used for growing muscle mass [1, 2, 3].
The excessive administration of insulin can lead to hypoglycemia (i.e. low blood sugar) very quickly. Severe hypoglycemia can cause unconsciousness or convulsions and lead to permanent brain damage or death [3, 4]. Insulin is one of a few doping substances associated with acute mortal danger if used.
Some known trade names (9/2014): Humulin, Novolin.
Finnish Center for Integrity in Sports FINCIS (previously the Finnish Antidoping Agency FINADA)
 Anderson LJ, Tamayose JM, Garcia JM. Use of growth hormone, IGF-1 and insulin for anabolic purpose: Pharmacological basis, methods of detection and adverse effects. Mol Cell Endorcinol. 2017: S0303–7207(17)30337–4
 Holt & Sönksen. Growth hormone, IGF-I and insulin and their abuse in sport. British Journal of Pharmacology. 2008;154(3): 542–56
 Ip E, Barnett M, Tenerowicz M, Perry P. Weightlifting’s risky new trend: a case series of 41 insulin users. Curr Sports Med Rep. 2012;11(4):176–9
 Auer & Siesjö. Hypoglycaemia: brain neurochemistry and neuropathology. Baillieres Clinical Endocrinology and Metabolism. 1993;7(3): 611–25