Clearly, you must talk to your GP, and not do what anyone of us says, as we are not GPs, but this is what I would be doing myself.
Firstly have I lost all the weight I wish to lose? (It is likely the weight loss will slow down a little without Metformin.)
If so, then it would be more sensible for me to reduce the dose of Metformin and confirm I am still in the low 30s in 6 months time, rather than stopping all the Metformin in one go.
If I wished to check for side effects, I would stop the Metformin for 2 weeks and see if I feel better, then restart it, remember to increase the dose slowly, and expect side effects for the first week of the restart.
I would not tell my GP what I was doing, as it is likely a GP would refuse to put me back on Metformin if my A1C increased a little a bit but still remained outside of the range for Type2. I would just stockpile the Metformin boxes, remembering to collect them every month, so the records showed I was still on them
It is sad we need to play these “games” with GPs, but they have to keep to the NICE guild lines, or at least their computers much show they did…..
Personly I am aiming for an A1C before 30 before I ease up on drugs or lifestyle.
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Remember that Metformin reduces insulin resistance a little, this results in insulin levels that are a little lower, and therefore our body reducing its own insulin resistance that then results in insulin levels that are once again a little bit lower. Hence we need to consider the long-term effects of Metformin on our insulin resistance, not just what our BG says over one week.
The above does not work, if we eat up to our meters, and hence stop the cycle by increasing our carbs. We can clearly make the above cycle go a lot faster by "low carb" etc, and without diet changes, Metformin just slows down the increase in insulin resistance.
When in double-blind studies, Metformin people were given Metformin or a "fake pill", the people on Metformin had their long-term A1C reduced by about 10, some people had it reduced by as much as 20. Yet we all know that on a day to day bases, we can't see much improvement from Metformin on our BG meters, as unlike "low carb" the effect cannot be measured on a meal by meal bases.