HI. Metformin never has a big effect on BS
Last year when my fasting readings were around 11 in the morning and 13 in the evening, the local pharmacy messed up my prescription and instead gave me Gliclazide, which no longer worked but was still on my prescription list due to the idiot at the surgery.
Because I was shielding that mistake resulted in being off Metformin for a week until it was resolved and the correct prescription was delivered. During that week my fasting readings went up to around 15 and 17.
In the previous weeks on Metformin my evening peak was a 17.6 with a few as low as in the 7s. But off Metformin my lowest was 11.4 on the first day, I had a few 20s, and my peak fasting reading was 30.5.
I guess big effects are relative?
As for other medications, after the week off Metformin my levels never returned to their previous level until I was put on Dapagliflozin. Though despite my fasting levels dropping a few points, it only lowered my HbA1c by half a percent / 5 mmol/mol. Granted that my situation may have had an effect on that, but other medications are not guaranteed to be more successful.
If there is nothing suitable for Amanda then a change of medication is the right thing for that reason, but I assume they have been having success with it which is why they would have preferred to continue with Bolamyn SR. So if they can find a replacement they can tolerate then they know it will work, rather than just taking something else with is own potential side effects and may not help.
I believe there are ten different modified release options for Metformin so hopefully one could still help: Diagemet XL, Glucient SR, Glucophage SR, Glucorex SR, Meijumet modified-release, Metabet SR, Metformin modified-release , Metuxtan SR, Sukkarto SR, Yaltormin SR.