Metformin.

My doctor prescribed me 1000mg of metformin. I tried taking 500mg twice a day and was beyond sick. I cut it down to 500mg a day and was still sick. For the past week I've been doing 250mg a day and haven't had to much of a problem. My question is..will 250 do anything at all. I know I need to up it back to at least 500 a day but I am kind of scared to. I am hoping that the 250 will help in someway. I have noticed it is keeping my sugars normal. Which were never extremely high to begin with but they are lower now. I was just hoping I could stick to the 250 instead of having to up it.