Creatine is a compound made from amino acids that is naturally produced in your body and mostly stored in your muscles. Creatine supplies energy to your muscles at times of physical exertion by increasing the formation of ATP molecules, which your cells use to do work. The amino acids within creatine are all glucogenic, although the production of glucose is not how creatine provides energy to your muscles.
Creatine Facts
Creatine is produced primarily within your liver from amino acids, and the vast majority of it is stored in your skeletal muscle although small amounts are found in your brain, liver and testes, according to University of Michigan Medical School. Specifically, creatine is synthesized from arginine, glycine and methionine. Animal-based foods are an important source of the amino acids that are used to make creatine, and vegetarians have significantly lower levels of it although they respond quickly to creatine supplementation, according to a Canadian study published in a 2003 edition of "Medicine and Science in Sports and Exercise."
Gluconeogenesis
Your body prefers to derive glucose from carbohydrates, which is used by your cells to help produce ATP energy molecules, among other purposes. With sufficient carbohydrate consumption, your body prefers to use the amino acids from protein metabolism to build other proteins and compounds such as creatine. However, a lack of carbohydrates and fat stimulate the metabolic process of gluconeogenesis, which extracts glucose from glucogenic amino acids and other compounds and prevents blood glucose levels from dropping too low. Most amino acids, including those within creatine, are potentially glucogenic.
Ketogenic Amino Acids
Ketogenic amino acids are not able to be used as a source of glucose, but they are converted into ketone bodies when carbohydrate sources are lacking. Exclusively ketogenic amino acids include leucine and lysine, although isoleucine, phenylalanine, tryptophan, tyrosine and threonine are both ketogenic and glucogenic, according to the 1999 book "Biochemical Pathways."
Creatine Function
Creatine's function is to increase the formation of ATP molecules inside of skeletal muscle so they can contract with greater force or longer duration, which is why bodybuilders and other athletes commonly supplement with it. Creatine is not used directly as a source of amino acids for the production of glucose under normal circumstances. The only end product of creatine degradation is creatinine, which diffuses into the bloodstream from the muscle and is excreted in urine. As such, creatine is not known to affect blood-sugar levels.
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