I've been taking Metformin ER for years with no problems unless I accidentally take it on an empty stomach, but last winter I began getting diarrhea that lasted for a few hours, usually in the morning, happening once every several weeks. Eventually I figured out that I was having problems with fatty foods, especially ones I've eaten for years, like yogurt, sour cream, stuff fried in oil, and oddly enough, eggs that have any white that is not solid. I have switched from eating those things and have been losing weight because of it. And that has meant my numbers are going down. I would say see what happens if you cut out certain foods. I had a cast-iron stomach all my life until I hit 70, so it can happen to anyone. I honestly think for me it has nothing to do with Metformin.