You have a difficult situation and I sympathize.
There is no reason for you to "keep her off the glucophage as long as possible". It is apparent she needs this medication now. You are endangering her life by suggesting "she wait".
This medication has been along for a long time and the side effects are minimal.
First, congrats to your mother for understanding how to manage and control her diabetes and for you for being a caring son. Here's my 2 cents;
1. The FDA allows home glucose test meters a plus/minus accuracy range of 20%. The reading is an approximate range within 20% of the actual. A good FREE meter is the J&J Ultra One Touch Mini. Google 'free ultra one touch' for the web site. I would also question the doctors test equipment as to when it was last calibrated.
2. The A1c has been used for more than 25 years as the major measure of glucose control and to establish targets for diabetes therapy. Use this formula to convert A1C into average glucose [eAG = estimated Average Glucose].
eAG(mg/dl) = (28.7 x A1c) – 46.7
Your mother's eAGis [28.7 x 6.5 = 186.55 - 46.7] = 139.85 mg/dl
"She is good on her diet but slips a bit." She either has to manage this better or take the Metformin [Glucophage] to help lower her levels. I take 500 mg [1 tablet] of Metformin w/food once daily with zero side effects.
Xanax is RX'd for panic attacks and anxiety disorders. Strange drug to RX an 83 yo.
3. Change, even for the better, is hard for a lot of people to accept. We don't know your mother so little advice can be given except keep trying. Let the new doctor know so he/she can make her next office visit a lot more comfortable and reassuring.
4. White bread and white pasta are both high in digestible carbs. High carbs will jack up her glucose levels. However, all is not lost. For white pasta, try the brand Dreamfields. Claims 65% lower glycemic index and only 5 digestible carbs. I can eat as much as I want w/o it affecting my glucose levels. And it has good flavor too. Also, whole wheat breads. I have local bakeries that supply my area markets. They look and taste like white bread, contain no sugar, and are very low in carbs. Both recommended for type 2 diabetics.
5. Try group counseling.
HTH