Hello,

Thanks for posting,
According to the manufacturers of metformin, it does not seem like depression or exacerbation of a depressive state is amongst the side effects and all the known side effects of metformin, none is seen to be able to lead to depression.
Since you made mention of the fact that your depressive state has deteriorated, it might be an indirect side effect as metformin is also known to lower TSH which could lead to low thyroid hormones, hence low metabolic activities of your system and hence a worst depressive state.
I suggest you discuss with your doctor. Maybe switching to another oral antidiabetic might make a difference or placing you on an antidepressant.

Hope this helps and wish you the best
Dr. Bernard

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Thanks for writing back,
You are write that is why they always precise that the side effects are not limited only to the ones that they have listed and depression might just be one of the rarest side effects metformin. If you are presenting with depression after taking metformin then it is most likely the factor aggravating your already depressive state.
If already taking antidepressants for many years, then the possibility for the antidepressant medication you are currently taking (if taking) no longer having effect is there. Long term use of medications that are suppose to affect the central nervous system, always results to tolerance or ineffectiveness of the medication.
Please, do book an appointment with your psychiatrist or treating doctor to discuss this issue with him/her and I hope you feel much better afterwards.

hope this helps
Dr. Bernard

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