Hello,
you need to get a second opinion. it would appear that metformin is no longer an adequate treatment for her.
The most appropriate treatment will be insulin.
You need to get a second opinion from a doctor and find one who will treat her properly.
Consider her FBS was 236. Normal FBS should be about 70 - 95 range.
With uncontrolled diabetes she is at risk of diabetic ketoacidosis, which can be fatal. Please also control how much carbs she eats. But bottom line is that she needs a dr who will give her the correct medication (insulin at this point).
I am NOT a Doctor I am a diabetic who is in control of my BG.
Your mothers FBS is very high with BG that high she will develop complications from diabetes. Carbohydrates raise blood sugar (BG) ALL carbs raise BG. whole wheat, rice, most fruit, pasta, potato... the list goes on if its got carbohydrates it will raise her BG. Metphorman can help, the max dose for met is 2250 mg/day so your mother has room to increase the met.