Some old drugs may have useful new benefits Photo CC http://www.flickr.com/photos/emagineart/
The drug metformin has been around since the early sixties. Whilst it has been prescribed since that time in the UK and Europe, misplaced concerns about serious side effect of a similar now discontinued drug prevented it being prescribed in the USA until the last decade.
Metformin has been shown to reduce cardiovascular mortality compared to other diabetes drugs and is used in some other conditions such as polycystic ovary disease, an illness often associated with obesity and presenting with menstrual irregularities.
Although not suitable for everyone, the main serious side effect of metformin is that it has been shown that it reduces the absorption of B12. This may cause serious problems if it is not recognized meaning that we should be checking for this in most patients. A small study has suggested that this B12 absorption problem might be prevented altogether if calcium intake is increased by calcium supplementation.
On the other hand metformin is now of considerable interest as a drug that may help prevent cancer. Patients with diabetes are more likely to get cancer than non-diabetic patients but this predisposition appears less in patients taking metformin. The cancer of most interest is the difficult to pick-up and often fatal pancreatic cancer. Research is on-going in non-diabetics to see if metformin can reduce cancer in other areas too.
It always seems interesting to me how often a drug is licensed for use in a particular area and then shown to be useful in other very different useful clinical areas.
There generally aren’t many useful drugs to help prevent cancer. Those that are taking metformin or are prescribed it should have their B12 levels checked but may be reassured that both their cardiac risks and cancer risks are likely to be less whilst taking the drug. There is also good evidence that metformin helps to prevent diabetes deterioration ( but weight loss and exercise is better).
A few years ago some diabetics were treated with diet alone. Diet alone is no longer recommended for most diabetics. Diabetes experts now recommend that for most diabetics metformin should be a first choice.