Im a type 2 on Byetta and I take metformin and Glipzide. I used to take Avandia but the Byetta got me off the stuff. So...without any meds I'll run high 300's for a BS reading. With just the orals I'll be somewhere in the 200's. We are talking morning fast here. With the 10mg of Byetta I'll be 75-100 for my morning numbers and 2 hours after eating (which is when the Byetta REALLY kicks in full strength) I'll be 60-80. Now this is assuming I haven't loaded up on carbs like a huge plate of french fries or had ice cream or something with lottsa sugar. So the Byetta definately is responsible for the lower numbers, but it has the help of the orals. Without the Orals, my numbers aren't below 100.
To answer your second question, the Amaryl is like metformin only stronger. It is there to promote and enhance the insulin sensitivity in your body, not stimulate your insulin production.
140 is the number that Endos would like Diabetics to shoot for, less than or equal to 100 2-hours after a meal is where normal people are and what you should probably shoot for as a Byetta user. As I said before, as long as your numbers are above 100 at night, even if you don't eat dinner, I don't think it will hurt you to take the Byetta. If your BS SHOULD dip to low, you will feel the effects (you'll feel cold, shakey, etc.) and you can then drink some orange juice to very quickly pull your BS back up. However, without a spike in your BS, I don't think the Byetta will pull you that low on an empty stomach. Otherwise, people that take it an hour before a meal would be in danger of going to low. Remember, Byetta's major feature is to be able to work on high BS and then shut off its effect as your levels return to normal. Hope this helps.