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One of the world's most commonly prescribed medications for diabetes is the inexpensive but highly effective drug metformin. Derived from a herb called goat's rue (Galega officianalis), metformin works by suppressing the liver's release of glucose from its stores of glycogen. Metformin is not a cure for diabetes. Most type 2 diabetics have about three times the normal rate of production of glucose from glycogen from the liver. Metformin only reduces sugar release from the liver to about twice the normal rate. With diet and exercise, however, in many cases of early type 2 diabetes, metformin alone is enough to restore normal blood sugar levels. In more advanced type 2 diabetes, metformin is an important part of blood sugar control.
Metformin was synthesized in the 1920's, but the introduction of insulin therapy eclipsed its importance in early twentieth-century diabetes treatment. The usefulness of metformin in treating type 2 diabetes was not forgotten, and it was approved for use in France in the 1940's, the UK in the 1950's, in Canada in 1972, and the USA in 1995. Because the patents for generic metformin expired long ago and even the branded forms of the drug Glucophage and Glucophage-XR have been out for many years, metformin is extremely inexpensive, just $4 to $5 a month in the United States, and even less expensive in some other countries. Despite its extremely low cost and limited potential for drug company profits, researchers are constantly finding new applications for the drug.
What Is Metformin Good For?
Metformin isn't just used to treat type 2 diabetes. It is also used to prevent prediabetes from progressing to a fully diabetic condition. Because metformin doesn't act by increasing insulin production, it does not cause weight gain (it is usually accompanied by slight weight loss, although this is due to fluid shifts rather than fat burning).
Because metformin increases insulin sensitivity, it is used to treat polycystic ovarian syndrome, a condition also known as PCOS. In PCOS, the ovaries are unable to stop receiving glucose from the bloodstream, and they react by overproducing testosterone. Metformin increases insulin sensitivity in other regions of a woman's body so that absorption of glucose is reduced in the ovaries, and hormonal imbalances are lessened.
Metformin is a potential anti-aging drug. It blocks a metabolic pathway known as mTOR, which regulates cell growth, cell reproduction, cell movement, and protein synthesis, all of which are critical in the development of cancer.
What Kinds of Cancer May Respond to Metformin?
Metformin seems to be a potential therapy for endometrial (uterine) cancer. A woman's womb, like her ovaries, is unusually sensitive to glucose. Because it is essential for ovaries to continue to receive sugar from the bloodstream to protect a woman's eggs that have not been released yet, and it is essential for the uterus to receive sugar from the bloodstream when a woman is pregnant, these tissues do not develop insulin resistance the same way that other parts of a woman's body may. When other parts of the body become resistant to insulin, these tissues cannot stop receiving sugar.