Could Metformin cause a Vitamin B12 defiency that would cause the neuropathy in my feet and hands to become worse? Would it also cause a slightly low Hgb? I have taken Metformin for 12 years and Starlix for my non-insulin Type II diabetes and my last A1c in February was 5.2 and has been below 6.0 for years.

Amy Campbell


Yes, it’s certainly possible that metformin can lead to a vitamin B12 deficiency. Researchers have looked at data from the National Health and Examination Study (NHANES) and have found that a vitamin B12 deficiency was present in 5.4% of people with type 2 diabetes who took metformin, compared to just 2.4% of people with type 2 diabetes not taking metformin. Other studies suggest that between 10% and 30% of people who take metformin have decreased absorption of this vitamin. Vitamin B12 is necessary for the health of nerve and blood cells, and also is needed to make DNA, the body’s genetic material. A deficiency of vitamin B12 may lead to weakness, constipation, mood changes, depression, loss of appetite and nerve problems, such as numbness and tingling. Lack of sufficient B12 can also lead to a condition called megaloblastic anemia, a condition that affects red blood cells and reduces the amount of oxygen delivered to cells and tissues. Ask your healthcare provider to check your blood level of vitamin B12, as the longer one takes metformin, the higher the risk for a B12 deficiency. Depending on your blood level, your provider may recommend B12, either in pill form or by injection, to both correct a deficiency and to supplement the amount of B12 you get from food sources (meat, poultry, seafood, eggs, milk, cheese).

April 6, 2013 at 8:59 am

2 replies

elmirerod1919 2014-09-20 13:48:21 -0500 Report

i look at metformin as i do arsenic. Just smell them. does this smell like something you should be putting in your body? Six years i took 1 gram twice a day and it did NOTHING. the doctors were so damn positive i was a type two, that they would not even consider the possibility that i may be a one. they kept me on metformin until i got a call from the endicrinologist telling me to flush them down the toilet they MISDIAGNOSED me as a 2. I said do you mean i have LADA? She said NO you are type 1 and were born like that the metformin killed millions of beta cells you used to make a little insulin now your pancreas makes none. So if i were you i would DEMAND a c-peptide test to make sure you will not be poisoned with metformin like i was. i had to demand this test. we were gonna try victoza till i told her, hence she is the only one who took me seriously i have always felt i had type 1 diabetes long before it even showed up on the test. is it a sixth sense? do i just know my body well? I make no claims whatsoever but i just have always known that when i was as young as six i refused to drink soda unless it was tab or diet pepsi or fresca. when i discovered they made them without sugar i thought as a little boy that would help my diabetes, i really thought i had it, in a way it did, i would hate to drink regular pepsi all my life then have to get used to diet believe me i have to have a pepsi for insulin shock and it's so gross you feel it rotting your teeth, really. But if i had it to do over again, i'd not touch another metformin till a c-peptide test is done.

1953Mercury 2013-05-08 10:17:21 -0500 Report

Thank you so much! I just do not understand why my PCP never even thought of this when he keeps telling me my Hgb seems to be getting lower and I have several of the other symptoms, also! Will sure talk to him about taking B12…! Sometimes we diabetics do have to be pro-activite in our management!