All people are different, and it may just be that they don't need as much Glucophage to treat their diabetes as you might need for your IR. You are right, it could also be that they are on something else. I starte out on 500mg of Glucophage to treat my diabetes and it worked well for me. I was eventually raised to 1500mgs but that wasn't totally because of the diabetes.
What doctors consider a failing fasting blood sugar seems to vary from doctor to doctor. I think mine said anything over 120 on a fast, but I might be wrong. My random glucose was 370 (After breakfast) so they had me do a fasting. That was 250 I think. So there was no need to worry about the borderline since I was nowhere near it.
Kathy
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Pregnant finally! EDD July 3,2002
Type II Diabetes 02/01
PCOS 05/01
"Life is 10% what you make it, and 90% how you take it."
-Irving Berlin