I started with the regular (non-timed release) and experienced horrible nausea and inability to keep anything down. After about a month, I was switched over to the timed-release Metformin 500 mg per day. That didn't go much better and the fatigue was horrible. I gave up on both Metformin and the statin I had been taking, as I wasn't going to take anything that made me feel like I was 110 years old. Without them I was able to increase my exercise routine and retake control of my life. My PCP never agreed, but she didn't have to live in my body.