Metformin’s herbal history
Diabetes UK is occasionally asked about the evidence for and effectiveness of a variety of alternative treatments such as herbal remedies or vitamin supplements. Although most of these are a waste of money (never believe anything that says you can ‘reverse diabetes’ – see the example in this spoof version of a ‘miracle cure’ website), plants genuinely do contain a variety of interesting chemical compounds and many are used in medicine.
Traditionally-used medicinal plants can contain many different active ingredients in varying concentrations. Some are harmful at low doses and some at higher doses. These chemical constituents can interact with prescribed medications and cause problems and these are some of the reasons that Diabetes UK does not recommend the use of a herbal remedy for the treatment of diabetes without consulting a doctor.
The Library and Information team at Diabetes UK receives a number of medical and scientific journals. We sift through the articles and provide a current awareness service for our colleagues. Recently we received a copy of the journal Diabetologia which had a lovely photograph on its cover of a plant called Galega officinalis (also known as French lilac or goat’s rue). Having recently had our 75th anniversary (Diabetes UK was founded in 1934) and being aware that it was really just one lifetime ago that insulin was discovered (1922) it was a nice reminder that many of our modern drugs have come from herbal traditions.
Galega officinalis is the ‘root’ of metformin, one of the most commonly used medicines for Type 2 diabetes. Although the plant itself was in use for hundreds of years, for a variety of medicinal and agricultural purposes (eg used to increase the milk yield in cattle) Galega officinalis is considered to be rather toxic and in several US states is defined as a ‘noxious weed’ that is harmful to grazing cattle. It was well known in mediaeval times as a treatment for symptoms for what we’d now call diabetes, including excessive urination. From the late 1800s the plant began to be investigated as the source of a treatment for diabetes.
The plant contains a variety of chemically similar components which vary in their levels of toxicity and ability to lower glucose levels. Guanidine compounds are more toxic and can cause plummeting glucose levels but the guanidine-like compound galegine lowers glucose levels less dramatically with slightly less toxicity. However, these native plant compounds are still not safe enough for use as a treatment.
In the early part of the 20th century chemists investigated derivates of these guanidine-like compounds, developing a range of ‘biguanide’ drugs, although advances in insulin therapy put these drugs on the back burner for a while. In the 1950s these biguanide drugs came on the UK market for Type 2 diabetes, but the one that stood the test of time is metformin (sold as Glucophage which means “glucose eater”) – it has been in use in the UK since 1958, though it was only licensed in the US in 1995.
Witters, L (2001) The blooming of the French lilac Journal of Clinical Investigation
108 (8): 1105-1107.
HCS Howlett and CJ Bailey (2007) Galegine and antidiabetic plants in Metformin: the Gold Standard. A Scientific handbook; Chichester: Wiley.
Bailey CJ and Day C (2004) Metformin: its botanical background Practical Diabetes International 21 (3): 115-117.
Hadden DR (2005) Goat’s rue – French lilac – Italian fitch – Spanish sainfoin: Galega officinalis and metformin: The Edinburgh connection Journal of the Royal College of Physicians of Edinburgh 35 (3): 258-260.