Its my understanding that anything under 70 is considered low. Sounds like you are doing well. When you get a reading of 70, you may want to eat a few nuts or a slice of cheese or something, esp. if you're expending a lot of energy. The only times i've ever went low on the metformin was when I didn't eat regularly and over-exercised. You're not likely to drop really low, but if you're like me, you can tell when you're in the 70's.