I am type 2 diabetic and have been on several different diabetic medicines and none of them have worked. So now trying the Metformin, was wondering why I am having rapid heart rate and nervousness and tightening in my chest, I am on 125mcg. of Levothyroxine for my throid, could this be a cause, could someone get bac to me on these questions, I am a female of64 yrs. with a history of heart problems,Liver Transplant and other medical conditions. Thank You JoAnne