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Vitamin B12 deficiency is a common problem. - 123RF
Vitamin B12 deficiency is a common problem. - 123RF

Diabetes drug lowers vitamin B12

New research has found that metformin, the most commonly used medication for treating diabetes, lowers vitamin B12 levels. This is a significant finding because while diabetics can develop peripheral neuropathy, being deficient in vitamin B12 increases the risk of developing peripheral neuropathy.

Peripheral neuropathy is a condition where the nerves of the limbs, most often the legs, are damaged. There are many possible causes of peripheral neuropathy but high blood sugar associated with diabetes is the most common cause. People with peripheral neuropathy typically experience tingling, numbness, burning, a lack of sensation and/or pain in the affected area (typically the legs and feet).

The results from this study were presented at the Society for Endocrinology BES 2018 conference in the UK. The 150 participants of the study were all women in the UK suffering with diabetes. The results found that most of these women being treated with metformin were not previously tested for their blood level of vitamin B12 and that almost 10 per cent of them were deficient in vitamin B12.

Dr. Kaenat Mulla, the study lead from the Nottingham University Hospital, said that she believes vitamin B12 is not tested more widely because metformin depleting it is “not a very well-known side effect.” Dr. Mulla added that the patients with diabetes who develop nerve damage have it "attributed to the fact that they have diabetes,” while it could actually be caused by vitamin B12 deficiency.

Vitamin B12 deficiency is a common problem, as was found in this original research. The people who are most likely to develop vitamin B12 deficiency are people who have absorption issues (colitis, celiac disease), pernicious anemia, thinning of the stomach lining (atrophic gastritis) and vegans and vegetarians. Vitamin B12 from food sources can only be found in animal-based foods such as milk, butter, cheese, eggs, fish, pork beef and other meats.

Veganism and vegetarianism are absolutely still healthy diet options, but people who avoid animal-based foods need to take care to ensure that they do not become vitamin B12 deficient. Symptoms of vitamin B12 deficiency include fatigue, weakness, shortness of breath, pale skin, peripheral neuropathy, depression, memory loss or behavioural changes.

If you would like to read the study, it can be found here:

If you have questions about nutrient deficiencies which could impact your health ask your naturopathic doctor.

Dr. Colin MacLeod ND is a naturopathic doctor practicing full-time in Upper Tantallon at MacLeod Naturopathic. His practice focuses on pain management and maintaining health through physical activity and diet. Visit him online at

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