Know a little about “Medicine” | Do you need to supplement vitamin B12 if you take metformin for a long time?

Aunt Sun was diagnosed with diabetes last week and the doctor asked her to take metformin. She carefully read the instructions and found that metformin may reduce the level of vitamin B12 in the body. So, do people who take metformin for a long time need to supplement vitamin B12 ?

Vitamin B12 deficiency can easily lead to megaloblastic anemia. Long-term use of metformin can cause a decrease in vitamin B12 levels. The possible mechanisms are: (1) changes in small intestinal motility stimulate intestinal bacterial overgrowth, competitively inhibiting vitamin B12 absorption; (2) changes in the level of vitamin B12-intrinsic factor complex affect the binding to cobalamin endocytic receptors; (3) metformin can inhibit the calcium-dependent absorption of vitamin B12-intrinsic factor complex in the terminal ileum (this inhibitory effect can be reversed by calcium supplementation). This is related to the dose and duration of metformin application. Some studies have shown that short-term (16 weeks) use of metformin can lead to a decrease in serum vitamin B12 levels. However, some studies have shown that taking metformin for less than 3 years has little effect on serum vitamin B12. Therefore, people who use metformin for a long time can test their vitamin B12 levels once a year, and if they are deficient, they should be supplemented appropriately.