More recent theories indicate that absorption of the B12 intrinsic factor complex uptake by cell membrane receptors in the ileum is known to be calcium-dependent, and metformin interferes with the calcium-dependent membrane action. This interference therefore affects B12 absorption and reduces B12 levels.

Does metformin reduce B12 levels?

The largest prospective placebo-controlled randomized trial to date evaluating vitamin B12 levels with metformin in type 2 diabetes showed that over 4.3 years, metformin reduced vitamin B12 concentration by 19%, increased homocysteine concentration by 5%, and was associated with an 11-fold increased risk in low vitamin ...

Why do you need B12 with metformin?

Why Some Diabetes Patients Taking Metformin Need More Vitamin B12. Researchers say metformin could be reducing vitamin B12 levels in some people with diabetes. The number one most prescribed drug to treat people with type 2 diabetes may actually be causing irreversible nerve damage in many patients.