Welcome to the forum
What lifestyle changes did you try as dietary changes are equally if not more important that metformin.
Many find a low carb approach successful in both losing weight and reducing blood glucose and some of the ideas in this link may help you with that.
https://lowcarbfreshwell.co.uk/
Other people find low calorie or a shakes-based regime can give a kick start but whatever you choose has to be enjoyable otherwise it will not be sustainable long term.
Keeping a food diary estimating the amount of carbs you are having will help you see how far away you are from the suggested no more than 130g per day if doing low carb, however if you are already having that sort of amount you may need to reduce it.