Can Metformin cause Vitamin B12 deficiency?

Firstly, let’s find out how Metformin works and what it does?

Insulin is a hormone produced by your pancreas and moves the sugar from your blood, like after a meal, into cells where they can be used as energy. You can think of insulin as key helping glucose into these various cells. Now what happens in DM2 is your body fat cells, liver cells and muscle cells do not respond well to insulin. This is called Insulin resistance. Your pancreas ends up producing more Insulin to try to push sugar into your cells, but it reaches a point when it can’t keep up and there is too much sugar in your bloodstream. Metformin reduces Insulin resistance thus helping sugar move into the cells. That’s why you want to take Metformin with your meals. This also reduces side effects from Metformin.

Metformin also reduces the amount of sugar produced by the liver. Did you know that the liver produces sugar? The problem is if you are a diabetic the liver ends up producing more sugar than you need because of insulin resistance. If you take Metformin the production of glucose is reduced in your liver, resulting in lower sugar levels in your blood.

The third way Metformin helps is it decreases intestinal absorption of glucose. If you eat a meal, food passes through your digestive system to your intestines. Therefore, after a meal your blood sugar level rises. Metformin delays the absorption of glucose during digestion.

For the most part Metformin is well tolerated. However, it does have some side effects especially when you are starting off with the drug.

Now what can happen if you have been on Metformin for many months or years. Metformin can cause Vitamin B12 deficiency. Low levels of B12 have been seen as early as 3-4 months after starting Metformin and in other cases they after been seen after 5-10 years of treatment. In a cross-sectional study looking at this up to 1/3 of patients on Metformin were B12 deficient.

What are the symptoms of B12 deficiency?

If you do have a B12 deficiency it can affect your blood count and in more severe cases it can affect your brain as well as your nerve cells.

A low blood count can affect different blood cells:

  • If your red blood count is affected, you become anemic. This means that you have a low red blood count. Your healthcare provider might say your hemoglobin is low. This can cause different symptoms such as fatigue, shortness of breath or feeling lightheaded.
  • If your white cell count is affected and decreased, you are at an increased risk for infection
  • Lastly, if your platelets are affected you are at an increased risk for bleeding and bruising.

What are the symptoms if your brain and nerve cells are affected?

Nerve cell with myelin
Nerve cell

If you become B12 deficient the protective covering called myelin around your nerve fibers are damaged resulting in different symptoms such as numbness and tingling of your feet or hands. This is called neuropathy. You might even have trouble walking; your mood can be affected presenting as irritability or depression. Memory can be affected presenting with forgetfulness, slowing of your cognition and it some cases even as dementia. That’s is why B12 levels are always checked if you are being worked up for dementia.

Here are 4 Tips to prevent B12 deficiency:

TIP # 1:

Make sure you are getting it from your diet. Some good resources are   in animal products, including fish, meat, poultry, eggs, milk, and milk products. Vitamin B12 is generally not present in plant foods, but a good resource are fortified breakfast cereals.

TIP# 2

Calcium supplementation seems to reduce this effect of Metformin. This study in Diabetes Care showed that increased intake of calcium reversed Vitamin B12 malabsorption of Metformin. The dose used was 1.2g of Calcium given daily.

Tip#3

If B12 deficiency is severe ( that is severe nerve damage) caused by Metformin discontinue Metformin and talk to your healthcare provider about an alternative way of managing your Diabetes. Progression of nerve damage can be stopped with adequate B12 supplementation, however, the nerve damage for the most part cannot be reversed. Neurological and psychiatric symptoms can improve over several months.

Tip#4

In mild to moderate cases, B12 can be replaced with 1000-2000 micrograms of cyanocobalamin. This is given daily, and your Doctor can follow up by checking your blood level for B12.In severe cases your healthcare provider might opt to replace your Vitamin B12 in the form of an injection. Some Doctors might start off with the injectable form of Vitamin B12 and later switch to oral supplementation.

Question of the Day?

If you are on Metformin did your Doctor check your B12 level?

Think your health and have a good day! See complete video here.

 

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