Does diarrhea from metformin mean it is working?

No. Diarrhea is a possible side effect of metformin, not evidence that it is producing the intended benefit. Losing fluid through diarrhea is also different from losing body fat. MedlinePlus metformin information.

A medication needs to make sense in ordinary life, including whether you can tolerate it. Tell your provider when symptoms started, how often they happen and whether eating or drinking has become difficult. That information helps determine whether the treatment needs reassessment.

At MedFIT, oral medications are a major treatment path, but no individual medicine has to be forced into a plan that is not working for you.

Next: Contact your prescriber about persistent or troublesome symptoms rather than adjusting the prescription yourself.