Blood sugar will change with stress among other things. I also gained huge amounts of weight on Metformin and it almost killed me. I had problems with my stomach and finally wound up in the hospital. I couldn't even keep water down. I met other people that said it affected their stomachs the same way. I knew about Avandia but didn't find this about Metformin until I was so sick. That was last summer and I still have problems. My doctor finally said (after I was in the hospital) that the Metformin was what was making me so sick. Because I am on some other meds, my weight has not come down significantly. Talk to your doctor about your bs levels, increase your exercise, and look at your diet. If you don't see changes look to your stress levels too. Stress really affects me.