People with type-2 diabetes are often prescribed a drug called metformin. It is quite effective in helping to control blood glucose. But there is a problem with this medication. Many patients stop taking it because it smells bad. Some people describe the odor as similar to stinky old socks or dead fish. They may think the medicine has gone bad. According to the manufacture, the chemical has an inherent aroma. The long-acting formulation of metformin is coated and less likely to smell offensive.
[Annals of Internal Medicine, Feb. 16, 2010]