The side effects associated with biguanide medications are few and can sometimes dissipate over time for some diabetics taking this class of oral diabetes medication.  One side effect for this type of oral diabetes medication that is common is upset stomach with nausea and diarrhea.

Another of the side effects that can be common with the biguanide class of oral diabetic medications can be a metallic taste in the mouth. While this cannot be dangerous for the diabetic, it can be very irritating side effect. The side effect alone may give the diabetic reason to ask their physician to change their oral diabetes medication.