What a strange situation - sugar in urine but not her blood :!: I DON'T BELIEVE IT :!:
Read with care - our opinions are based on experience & should not be seen as countermanding medical advice. Diabetes is a disease that benefits greatly from self-regulation rather than sticking to fixed doses. There is even an official programme called DAFNE - "Dose Adjustment For Normal Eating."
What does she eat? Has she been given dietary advice? A large dose of presumably metformin can be upsetting. Many people on this forum have reduced & controlled their blood sugars by cutting down their carbohydrates drastically. That means eating no breakfast cereal, & very little bread (max 1/2 slice per meal) potato, rice, pasta.... Increase the proteins & veg to compensate. They take longer to digest so she won't feel hungry - & if she does, have a piece of cheese, or an egg.
If/when the blood sugars come down, she can reduce the tablets.
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Actually it means ignoring the NHS dietary advice which is to "eat starchy foods at each meal." That advice means giving the tablets carbs to work on. The forum advice reduces the need for tablets. I'm down from 3 to 2, & have lower blood sugars that when I was on 3. In a few months my weight, cholesterol & tiredness were reduced, & serious muscle pain ended.
I followed the "eat starchy foods at each meal" advice for 8 years, with ever increasing sugars & tablets until I found this forum. 6 months ago I feared I was becoming disabled with muscle pain. Now I'm playing tennis again at club standard.