Metformin B12 Deficiency

Dr Jedha, Host

Hello wonderful people. Today, we’re talking about metformin, vitamin B12 deficiency, and why understanding both the benefits and potential downsides of medication matters.

Metformin is usually the first medication prescribed for type 2 diabetes, and it’s also increasingly being prescribed for people with prediabetes.

Without a doubt, metformin has helped millions of people around the world manage their blood sugar levels. It’s been around for decades, it’s relatively inexpensive, and for many people it can be an effective medication.

So, this isn’t an episode about metformin being a bad medication or telling people they should stop taking it. 

But like every medication, metformin can come with side effects, and it’s important that people understand both the benefits and the potential downsides.

Side effects are one reason many people prefer not to take medication or they may wish to get off metformin and other diabetes meds, that’s certainly a good reason and reducing or getting off meds is certainly possible, as we’ve seen in many of our members.

With metformin, some of the more common side effects tend to occur when people first start taking it. These can include nausea, diarrhea, stomach upset, bloating, and sometimes even a metallic taste in the mouth. Some people also notice a reduced appetite.

For many people, these symptoms can improve over time. For others, though, digestive issues can persist and become one of the reasons they struggle to continue taking the medication. But today, we’re here to focus on a side effect that often receives much less attention. And that’s vitamin B12 deficiency.

This is something that can develop slowly, sometimes over several years of taking metformin. Because it happens gradually, many people don’t realize it’s occurring. They may simply assume they’re getting older, feeling run down, or experiencing symptoms related to diabetes itself.

The issue isn’t that metformin is unsafe. The issue is that many people take metformin for years and may never be told that it can affect vitamin B12 levels or that monitoring may be appropriate, particularly with long-term use. And this matters because vitamin B12 plays an important role in nerve function, red blood cell production, energy levels, and brain health.

So, while metformin can certainly have benefits, it’s also important to understand the whole picture and make sure we’re paying attention to potential nutrient deficiencies that could be affecting how you feel.

So, why does this happen?

To understand that, let’s briefly talk about what vitamin B12 actually does. Vitamin B12 is an essential nutrient that plays a critical role in keeping your nerves healthy, producing red blood cells, supporting DNA synthesis, and helping with normal brain function and energy production.

Unlike some vitamins that need to be consumed regularly because the body doesn’t store much of them, we can store several years’ worth of vitamin B12 in the liver. That’s one reason why deficiency often develops slowly and can easily go unnoticed.

Now, vitamin B12 from food has quite a complicated absorption process. When you eat foods that contain vitamin B12, such as meat, seafood, eggs, and dairy foods, the vitamin eventually binds to a protein called intrinsic factor. This combination then travels to the last part of the small intestine, called the ileum, where vitamin B12 is absorbed into the body.

Research suggests that metformin can interfere with this absorption process. One of the leading theories is that metformin affects a calcium-dependent mechanism that’s needed for the vitamin B12-intrinsic factor complex to be properly absorbed in the small intestine. Essentially, the body becomes less efficient at taking up vitamin B12 from food.

This doesn’t mean everyone taking metformin will develop a deficiency. But it does mean that over time, some people may absorb less vitamin B12 than they need. Since deficiency develops gradually, it can take years before symptoms become obvious.

And we know that certain factors can increase the risk of B12 deficiency. The risk appears to be higher in people who have been taking metformin for many years, take higher doses of metformin, are older adults, already have lower vitamin B12 stores, and among those whole eat little or no animal foods, such as some vegetarians and vegans.

The challenge is that many people have no symptoms initially. Their vitamin B12 levels may be slowly declining, but because they still feel relatively well, neither they nor their healthcare team realize anything is changing. Then, several years later, symptoms such as fatigue, numbness, tingling, memory problems, or balance issues may start appearing.

And because these symptoms develop so gradually, it’s easy to assume they’re simply part of aging or part of living with diabetes. That’s why this issue deserves more attention. Vitamin B12 deficiency associated with metformin usually doesn’t happen overnight. It’s often a slow, silent process that can develop over many years, which is precisely why awareness and appropriate monitoring can be so important.

Now, here’s where things get really interesting. The symptoms of vitamin B12 deficiency can be surprisingly easy to overlook because they’re often vague at first. Remember, vitamin B12 is involved in nerve health, energy production, and brain function. So when levels start to fall, a wide range of symptoms can develop.

Let’s start with the nervous system. Some people begin experiencing tingling or numbness in their hands and feet. Others describe burning feet, pins and needles, or a feeling that they’re wearing socks when they’re not. Some people notice changes in their balance. They may feel less steady on their feet or have difficulty walking in the dark. Muscle weakness can also occur.

And here’s where things can become particularly confusing for people with diabetes. Many of these symptoms can look remarkably similar to diabetic neuropathy. So, someone may assume their diabetes is causing the problem, when vitamin B12 deficiency could be contributing or making the symptoms worse.

Then there are the symptoms that affect the brain. People sometimes report brain fog, memory problems, difficulty concentrating, or simply not feeling mentally sharp anymore. Again, these symptoms often creep in slowly. It’s not like waking up one day and suddenly noticing a major change. It’s more that over months or years, you realize your energy isn’t what it used to be or that you’re forgetting things more often.

Then there are the general symptoms. Fatigue is probably one of the biggest ones. People may feel tired all the time, even after a good night’s sleep. Some describe having less stamina, feeling weak, or becoming short of breath more easily. The tricky part is that none of these symptoms automatically mean you have a vitamin B12 deficiency. But if you’re taking metformin and you’ve been experiencing some of these changes, it’s worth being aware that vitamin B12 could be part of the picture.

And one final point that’s really important. Some nerve damage associated with severe, prolonged vitamin B12 deficiency may not be completely reversible. That’s one reason this conversation matters so much. Because recognizing the possibility of vitamin B12 deficiency early may allow people to investigate it before symptoms become more significant.

So, if metformin can affect vitamin B12 absorption and the symptoms can be easy to miss, the obvious question becomes: Should everyone taking metformin have their vitamin B12 levels checked?

The answer isn’t necessarily that everyone needs constant testing, but there is growing recognition that vitamin B12 deficiency in people taking metformin is probably under-recognized. Many diabetes organisations and clinical guidelines now recommend that periodic vitamin B12 monitoring should be undertaken, particularly in people who have risk factors or are experiencing symptoms that could suggest a deficiency.

For example, it may be worth having a conversation with your healthcare provider if you’ve been taking metformin for several years, as we know that increases your risk of deficiency.

It may also be appropriate if you’re experiencing some of those symptoms we covered, such as tingling or numbness in your hands or feet, burning sensations in the feet, increasing fatigue or weakness, balance issues, brain fog or memory concerns or worsening neuropathy symptoms. 

If you’re taking metformin and some of these symptoms sound familiar, talk to your physician and request a B12 test and ask whether monitoring makes sense in your situation. And even if you’ve been taking metformin for sometime, it just may be worthwhile requesting a B12 test. Because that is the great thing, testing B12 is easily done via a blood test and correcting B12 deficiency can be done through supplementation and if needed, through B12 injections. 

While medications can be helpful in lowering blood sugar, they aren’t always the best solution. One downfall is that all medications do come with potential side effects. Also, medications only have a limited effect. For example, metformin taken at the maximum dosage can only lower A1c by 1.5%. We also know that medications are overprescribed and that it’s very common to see people over 60 on multiple medications, many of which may not be necessary. 

That’s why so many of our members are interested in managing and treating their prediabetes and type 2 diabetes with nutrition and lifestyle. They simply want to understand what they can do themselves to improve their blood sugar, potentially avoid additional medications, or, where appropriate and with their doctor’s guidance, reduce some of the medications they’re taking. 

Let me give you two examples.

Lisa joined us with prediabetes and an A1c of 6.0%, we shared her story in episode 61. She had previously experienced gestational diabetes and was also going through breast cancer treatment so she wanted to avoid taking any other medications. She wanted to improve her health through nutrition and lifestyle changes.

After taking our Prediabetes Reset Program, Lisa lowered her A1c to 5.5% and lost 13 pounds (that’s around 6kg). She moved her blood sugar back into the normal range and avoided needing additional medication.

Then there’s Curtis.

Curtis had been living with type 2 diabetes for more than 12 years. His A1c was 10%, his fasting blood sugar was over 200 (that’s over 11), and he was taking 2,000 milligrams of metformin per day.

Over approximately nine months, he lowered his A1c to 5.6%, his fasting glucose to 86 mg/dL (that’s 4.8 mmol/l), and lost 36 pounds (that’s around 16kg). Under his doctor’s supervision, he was able to stop metformin and reduce his blood pressure medication.

Now, these stories don’t mean everyone can stop medications, nor should anyone discontinue medication without speaking with their physician. But they do highlight something incredibly important. Nutrition and lifestyle changes can be remarkably powerful – they help prevent additional medications from being needed, and for some people, they may even reduce medication requirements over time. Even if you are taking medications, nutrition and lifestyle changes are still very important and be a major part of your treatment and management plan. It’s so important to focus not only on medications, but also on addressing the underlying factors that influence blood sugar in the first place, and nutrition and lifestyle can help you do that.

If you’d like support using nutrition and lifestyle strategies to improve blood sugar and potentially reduce medication requirements, head to Type2diabetestalk.com/programs and join us as a member. 

Thanks for listening today, and see you in the next episode.

Dr Jedha, over and out.