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Diabetes medication may deplete vitamin B levels

- and cause serious physical and psychological disease

Diabetes medication may deplete vitamin B levelsType 2 diabetes is spreading like a bushfire, and taking the diabetes drug metformin increases the risk of vitamin B12 and vitamin B6 deficiencies. Lacking these two important B vitamins is associated with fatigue and cognitive dysfunction that resembles dementia. This was shown in a study that is published in The Journal of Clinical Endocrinology and Metabolism. An earlier study that was presented at an endocrinology conference in Glasgow suggested that type 2 diabetics that take metformin on a regular basis have their vitamin B12 status checked once a year to prevent irreparable damage to the nervous system. It is also important to focus on vitamin B6, which is also crucial for the brain and nervous system.

Type 2 diabetes is often associated with an unhealthy diet and lifestyle and eating too many refined carbohydrates. When these calories enter the bloodstream in the form of pure glucose, the pancreas churns out large quantities of insulin to help channel the glucose into the cells. This may lead to insulin resistance, where cells become less sensitive to insulin and their uptake of glucose is impaired correspondingly. Type 2 diabetes is characterized by elevated blood sugar and insulin levels. The combination of persistently elevated blood sugar levels, elevated insulin, and insulin resistance is extremely bad for your health, as it increases the risk of overweight and inflammation and can cause damage to the eyes, kidneys, nerve paths, and blood vessels, which may result in disabling conditions such as impaired vision and cardiovascular disease. The early stage of type 2 diabetes is called metabolic syndrome and is characterized by elevated cholesterol levels caused by blood sugar disturbances and has nothing to do with the cholesterol in the diet.

Metformin therapy and its side effects

Metformin is the most frequently used and most effective medication against type 2 diabetes. It works by increasing the uptake and effect of insulin in muscle tissue. At the same time, metformin lowers the release of glucose from the liver. Metformin is associated with side effects such as reduced appetite, diarrhea, nausea, stomach pain, and taste disturbances, but these problems are often transient. Science has known for years that metformin also causes vitamin B12 deficiency, but there still are no effective guidelines in this area.
In the study that was presented at an endocrinology conference in Glasgow, the researchers had observed that 64 percent of the female diabetics, who were treated with metformin, had not had their vitamin B12 levels checked, and 10 percent of them had a deficiency of the nutrient. Only six percent of them were given supplements of vitamin B12 together with their medicine.
Lack of vitamin B12 is insidious and may cause fatigue, poor memory, and other symptoms that are related to the nervous system and resemble normal ageing processes. Some of these nerve-related symptoms, including diabetic neuropathy, are irreversible. The scientists therefore suggest that type 2 diabetics, who take metformin, have their vitamin B12 levels checked at least once a year.
As mentioned earlier, metformin may also cause a vitamin B6 deficiency that can result in fatigue, changes in brain function, depression, and poor utilization of magnesium, which has other roles in the nervous system. With vitamin B6, unlike with vitamin B12, there are no official guidelines to help patients get enough of this nutrient.

Vitamin B12’s essential functions

Vitamin B12 is important for cellular energy turnover and the formation of red blood cells. Vitamin B12 converts homocysteine into methionine and S-adenosylmethionine (SAMe), which is important for the immune system, for nerve transmissions, and for the mental balance. Vitamin B12 also helps form the myelin sheath that protects and isolates the nerves in the same way as the plastic coating protects the electric wires.

Symptoms of vitamin B12 deficiency

  • Anemia accompanied by fatigue, heart palpitations and other symptoms caused by lack of oxygen in the cells
  • Poor memory, mental lethargy, dementia, and muscle weakness that is often associated with ageing
  • Peripheral neuropathy (nerve inflammation) that causes damage to nerves in the arms and legs
  • Pernicious anemia caused by a lack of a protein called intrinsic factor that is responsible for the uptake of vitamin B12
  • Increased risk of osteoporosis and Alzheimer’s disease

Sources of vitamin B12 and things that cause a deficiency

Vitamin B12 is mainly found in animal sources like meat, fish, eggs, and dairy products. This means that vegetarians and vegans in particular are at risk of a deficiency. In order for the body to absorb vitamin B12 from the diet, it needs a protein called intrinsic factor that is produced in the gastric mucosa. Intrinsic factor attaches to vitamin B12 and carries it from the small intestine into the body. Coli bacteria in the small intestine are also able to produce vitamin B12, but experts have different views on its uptake that requires intrinsic factor and takes place in the small intestine.
The ability to absorb vitamin B12 is reduced with age and in individuals with too little stomach acid. Other limiting factors are overconsumption of alcohol, impaired ability to store the vitamin in the liver, estrogen, birth control pills, sleeping medication, and prolonged use of other types of medicine.

Supplements and injections

Many supplements contain large quantities of vitamin B12 because it is so difficult for the body to absorb the nutrient. Vitamin B12 lozenges give much better absorption of vitamin B12 because the nutrient is absorbed directly by the oral mucosa.
Vitamin B12 supplements should normally be taken together with folic acid, vitamin B6, and other B vitamins that work in close collaboration with B12. Supplements should not be taken at the same time as antacids. In some cases, such as when a person has pernicious anemia, vitamin B12 is given as injections.


Porter KM et al. Hyperglycemia and metformin use are associated with B-vitamin deficiency and cognitive dysfunction in older adults. J Clin. Endocrinol Metab. 2019 Mar 28.

Society for Endocrinology. Routine vitamin B12 screening may prevent irreversible nerve damage in type-2 diabetes. ScienceDaily 2018

Vanita R Aroda et al. Long-Term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study. Endocrine Society 2016

Pernille Lund. Sådan får du styr på dit blodsukker og din vægt. Ny Videnskab 2013

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