Anemia - related to Metformin?

Hi Everyone,
I've recently been diagnosed with Anemia, so have been taking vitamins. I found out through my Diabetes Forecast recently that Metformin may cause a vitamin B12 deficiency, which turns into anemia. I am a LADA Type 1, so I have been taking Metformin instead of 1 insulin unit with breakfast and also at dinner (mostly because I was incorrectly diagnosed as type 2 and the Metformin works pretty well for me). I've been overcome with lethargy lately, so I decided today to give up the Metformin and just do an extra insulin shot/day just in case the Metformin is contributing to my anemia. I'm curious if anyone has dealt with this, has information to share, etc. Thanks!


I'm confused how a B12 deficiency turns into iron deficiency anemia. Maybe if you don't have enough B12 your body doesn't process iron properly?

I can't explain medically but Anemia are one of the things that Diabetes can affect. I've had T1 most of my life and have Anemia that long also.

Betty J - how do you treat it?

oMy Educator told me years ago if you can not have lows for a few weeks you can regain the symptoms. I find it to be true if I can avoid lows...not as if we plan them.

Metformin can cause a malabsorption of vitamin B-12. This can cause a form of anemia and low levels of B-12 can also cause a form of neuropathy. It is estimated that perhaps 30% of patients on metformin have evidence of malabsorpion. Some people suggest that supplementing calcium can avoid the issue, but I'm not convinced. I've been on metformin for years and supplement (in addition to my Costco performance vitamin) with B-100 which contains 1600% of the RDA. In the last year I had my B-12 levels tested and they are normal.

I think it is better to just take a supplement and get all the advantages of improved insulin sensitivity from metformin. If you only take a total of 8 units of insulin a day, then you probably don't need it.

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Hi @Betty_J what kind of anemia do you have? iron deficiency anaemia?

@S_Harper and what’s your kind of anemia? what I understand is that metformin will cause the malabsorption of vit. B12, like @Brian_BSC said, so you can be on metformin and supplement B12.
I have anemia, since I was a child, because of iron deficiency, not I just found out I have B12 deficiency too, and LADA (GAD antibodies positive), then I was wondering if they are all correlated… GAD antibodies is present in pernicious anemia, but I was never diagnosed with pernicious anemia

I may sound like a broken record, but anemia (iron-deficiency or B-12) can also be a sign of celiac disease. In fact, that’s the only symptom (no intestinal issues) I had with the exception of a Hashimoto’s Thyroiditis diagnosis (strong link), that led my doctor to my celiac diagnosis. I had anemia all my life. Doctor’s blamed two things: 1) I was a menstruating woman and 2) I had a genetic anemia – Thalasssemia. Turns out I had celiac disease too which was causing low ferritin scores causing an iron-deficiency on top of my Thals.

TD1 and and celiac disease are strongly linked. About 10% of TD1’s have celiac disease. Consider getting tested if you have TD1 and are anemic or have struggled with unexplained anemia.

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What was the order of your diagnosis? Do you take insulin and thyroid supplements? How was your experience with gluten, did you feel better after cutting it out of your diet? Did it help with your anemia?

I always had anemia (iron-deficiency). 3 months ago I got to know I have diabetes type 1 (I am not on insulin yet, I’ve been controlling my bg with diet and exercise), I got tested for hashimoto and I have antibodies against my thyroid too (although it is currently working fine, TSH and T4 are ok).
Now I am waiting on the results of transglutaminase antibody to check celiac.

Does anyone know anything to stop this autoimmunity thing? I was reading about “leaky gut” I think it’s all correlated. I was wondering if it would help to try some different diets, like not eating cow milk… (but how would I know if it’s helping?)


Hashi’s 1997, Armour Thyroid Antibodies, over 2,000. Took small amount thyroid even when TSH was normal, but eventually increasing the dosage.
Celiac Disease: 2013 Only DGPS IGA positive, biopsy Marsh Stage IIIB.
Diabetes: 2014 (not typed, diet controlled)

I will caution you that because you have Hashi’s, I would strongly recommend an entire celiac panel (TTG, DGP, EMA). My TTG was and is always negative. If my GI had not ordered the entire celiac panel, my diagnosis would have been missed!!!

B12 is OTC. It can’t hurt. I have been on Met for a year and started b12 sub lingual. On my own I would add. Because of good advice from these forums. I no longer have pain in my feet.

@Cyclinglady thanks for your reply. And do you feel difference in your body? When you eat gluten?

@McChesney that’s sounds cool with me too. Supplement it… I haven’t seen it like sublingual here where I live, I will look for it. I take injections, and it hurts. Rs… 1injection a month 5000 B12.

What is a good level to keep your B12?

I would never recommend even experimenting with a gluten free diet (along with all the leading celiac disease researchers/doctors) until celiac disease has been ruled out. Going GF is hard, super hard.

If your TTG result is negative ask for the EMA and DGP celiac blood tests. I already stated that about 10% of TD1 patients go on to develop or are diagnosed with celiac disease. Anemia is now the leading symptom for celiac disease.

My iron-deficiency anemia resolved because with intestinal healing, I was able to absorb iron from food sources.

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I am curious about the type of B12 deficiency that metformin causes. Does it cause just a B12 deficiency or does it trigger pernicious anemia?

Pernicious anemia is an auto-immune disease that causes a deficiency of B12 due to the lack of intrinsic factor.

The intrinsic factor is a substance secreted by the stomach that enables the body to absorb vitamin B12. Without the intrinsic factor, the body cannot absorb the B12 that is ingested, either from food or supplements, so red blood cells are not made. B12 is required to make red blood cells.

If one has a B12 deficiency caused by pernicious anemia, it doesn’t do any good to take an oral supplement of B12, one must have an injection of it at least once a month for the rest of their lives.

Pernicious anemia runs in my family – many males in my family have had it, including my father. So far, I’ve been spared… In many cases, sub-lingual B12 can help those with this issue, as this delivery system avoids the stomach in the absorption. Just in case, I took B12 during the short time I was taking Metformin.

As for whether or not Metformin can cause iron-deficient anemia… Several years ago, when my mother was seen at the May Clinic, she had become quite anemic. They decided that Metformin had caused it and changed her meds. It’s several years later and she’s just as anemic or worse without the Metformin, so it was NOT the cause in her case. No one has determined what is was, but not Metformin.

My TTG results came back negative. But I have antiparietal cells antibodies, indicating autoimmune gastritis (what explain the iron deficiency anemia and B12 deficiency). But I will talk with the doctor about the need of doing the other celiac tests.