It is impossible for your healthcare provider to know whether you will develop erectile dysfunction while taking metformin. However, if you develop any sexual side effects while taking this drug, make sure to talk with your healthcare provider. There is treatment that he or she may be able to recommend, such as an erectile dysfunction medication. Depending on the severity of your sexual side effects, he or she may also recommend that you adjust your metformin dosage or try another diabetes medicine.
One final point to keep in mind is that diabetes itself is a common cause of erectile dysfunction. Therefore, it is possible that metformin might actually help with erectile dysfunction by getting blood sugar levels under control.