Metformin's what I'm on as well. I was on Avandia, too, until about a year ago (my PCP looked at my A1C and decided it was overkill I think). Its rare that my blood sugar goes below 100, and equally rare that it gets over 180 after eating--I divy up my meals into little snacks, mostly cereals, throughout the day, drink a lot of water after noon (black, white or green tea before), and sometimes have peppermint tea later in the afternoon. One of the things I botched up, and which probably contributed to my being off yesterday was that normally I'd take my thyroid med in the morning, but I didn't, so in addition to taking too much Metformin the day before (I usually take 1 in the AM, 1 in the PM, but because I wound up double-dosing, then inadvertently took a 3rd pill before bed with my other night-time meds), my metabolism was almost certainly off--a comedy of errors that had I just slowed things down, stuck to my routine and not gotten caught up with "gotta get A, B & C done now now NOW"--I'd probably not have wound up the way I did. But it could have been worse, too, and the fix was quick and simple--get a little sugar into my system as quick as possible so that the excess insulin in my system could go after it. Live and learn.
Now if I can just lose some of this water weight I put on!