Why Do My Hands Feel “Electric”? What Every Metformin User Needs to Know

Why Do My Hands Feel “Electric”? What Every Metformin User Needs to Know

“Pharmacist, my fingers keep tingling, almost like a small electric current. Is my diabetes medicine damaging my nerves?”

I hear this concern more often than you may think. When the tingling starts after years of taking metformin, it is easy to blame the medicine.

Here is the reassuring part: metformin does not directly damage your nerves. However, long-term metformin use can reduce Vitamin B12 absorption in some people. When B12 becomes too low, nerve symptoms may develop.

This does not mean every tingling sensation is caused by low B12. But for someone taking metformin, it is an important and treatable possibility worth checking.

⚡ Why Do My Hands Feel “Electric”?

Our nerves carry messages between the brain and the rest of the body. When a nerve is irritated, compressed, or not receiving the nutrients it needs, these messages may not travel normally.

Instead, you may feel tingling, buzzing, pins and needles, burning, numbness, or a mild “electric shock” sensation. There are several possible causes:

  • Temporary pressure on a nerve (e.g., sleeping on your arm)
  • Carpal tunnel syndrome or a trapped nerve in the neck
  • Diabetic peripheral neuropathy (nerve damage from high blood sugar)
  • Thyroid or kidney issues
  • Nutritional deficiencies, particularly Vitamin B12 deficiency

However, symptoms alone cannot reliably identify the root cause. This is where guessing becomes risky.

🧠 Low Vitamin B12: More Than Just Feeling Tired

Think of your nerves as electrical wires. Every wire needs a protective outer layer to keep its signals moving smoothly. Your nerves have a similar protective covering called the myelin sheath.

Vitamin B12 is needed to maintain healthy nerve function and support myelin formation. It also helps your body produce normal red blood cells and DNA.

When Vitamin B12 becomes too low, you may experience:

  • Tingling, numbness, or burning sensations in the hands and feet
  • Unusual tiredness, weakness, or feeling unsteady on your feet
  • Difficulty concentrating or memory changes ("brain fog")
  • A sore, unusually smooth, or red tongue.

⚠️ Important: Nerve symptoms can appear even when your hemoglobin level is still completely normal. A normal Full Blood Count (FBC) does not rule out Vitamin B12 deficiency!

💊 What Does Metformin Have to Do With Vitamin B12?

Metformin is a widely recommended first-line medicine for Type 2 diabetes including in Malaysia’s clinical practice guidelines. It helps control blood glucose and remains an important part of reducing the risk of long-term diabetes complications.

However, long-term metformin use can interfere with the absorption of Vitamin B12 in the small intestine, making it harder for some people to obtain enough B12 from food.

Because the body stores Vitamin B12 in the liver, your levels usually fall gradually over months or years. This explains why someone may take metformin for several years before noticing any symptoms.

How Common Is Vitamin B12 Deficiency? 

  • Malaysia’s NPRA states that Vitamin B12 deficiency may affect up to 1 in 10 people taking metformin. 
  • Clinical Trial Data: A landmark randomized clinical trial (de Jager et al.) showed that patients on long-term metformin experienced an average 19% reduction in Vitamin B12 levels.
  • Malaysian Data: A Malaysian study (Krishnan et al.), identified confirmed B12 deficiency in 28.3% (close to 1 in 3) of participants and taking metformin for more than five years was associated with more than twice the likelihood of B12 deficiency. 

Why the difference? The exact risk depends on your daily metformin dosage, how many years you've taken it, and your individual digestive health.

Who Should Pay Closer Attention?

Risk Factor

Why Risk Increases

High Metformin Dose

Risk generally increases as the daily metformin dose rises. Several studies have reported greater risk at doses of approximately 1,500–2,000 mg daily or above.

Long Duration of Use

Longer treatment allows the effect of reduced absorption to accumulate. Risk increases after 3 years of use while comparing to <3 years.

Older age

Reduced stomach acid and food-bound B12 absorption become more common with age.

Dietary Patterns

Following a strict vegan or vegetarian diet (B12 is found mostly in animal products).

Co-Medications

Using daily acid-reducing medicines like PPIs (e.g., omeprazole or pantoprazole).


What Happens If Low B12 Is Left Untreated?

  1. Nerve Symptoms May Worsen: Occasional tingling can progress to persistent numbness, burning pain, or reduced sensation. Loss of joint position sense can cause unsteadiness when walking, increasing fall risks.
  2. Anaemia May Develop: Low B12 impairs red blood cell production,causing tiredness, weakness, breathlessness, dizziness or palpitations.
  3. Recovery May Become Incomplete: When deficiency is identified early, blood abnormalities and some symptoms often improve with treatment. Neurological recovery may take several months. 

What Should You Do Next?

🛑 1. Do NOT stop metformin on your own

Stopping metformin without professional advice may cause your blood glucose to rise and worsen your diabetes control. Metformin can usually be continued while Vitamin B12 deficiency is assessed and treated, unless the prescriber identifies another reason to change it.

💬 2. Speak to your pharmacist or doctor

Share your exact daily metformin dose, how long you've taken it, when the tingling started, and any other symptoms such as fatigue, weakness, a sore tongue, poor balance or memory changes.

💊 3. Treat according to your result

If B12 deficiency is confirmed, your healthcare provider will guide your treatment:

  • Oral B12 Supplementation: NICE recommends at least 1 mg (1,000 mcg) of oral Vitamin B12 daily when oral replacement is used in someone with suspected malabsorption.
  • Vitamin B12 injections: Your doctor may recommend injections when neurological symptoms are significant, deficiency is severe, oral treatment is unsuitable, or reliable absorption is uncertain.

🚨 When to Seek Immediate Medical Attention

Go to the nearest emergency department immediately if you experience:

  • Sudden weakness or numbness on one side of the body
  • Facial drooping or asymmetrical smile
  • Difficulty speaking or slurred speech
  • Sudden, severe loss of balance or coordination
  • Rapidly worsening muscle weakness
  • These signs indicate a potential stroke or neurological emergency, do not wait for a B12 blood test.

Final Message

Your comfort matters just as much as your daily blood sugar readings. You don't have to choose between managing your diabetes and having healthy, painless nerves.

Remember:

  • The tingling is not your metformin damaging your nerves directly.
  • It can be a sign of low Vitamin B12 and other causes.
  • Vitamin B12 deficiency is treatable, and earlier assessment offers the best chance of recovery.

Have concerns about metformin, tingling or your Vitamin B12 level? 

Walk into your nearest Alpro Pharmacy branch or message our pharmacists online. We are here to give you personalized, easy-to-understand advice for your health because you deserve to feel reassurance while managing your diabetes.

References

  • Ahmed, M. A., Muntingh, G. L., & Rheeder, P. (2016). Vitamin B12 deficiency in metformin-treated type 2 diabetes patients: Prevalence and association with peripheral neuropathy. BMC Pharmacology and Toxicology, 17, Article 44. https://doi.org/10.1186/s40360-016-0088-3
  • American Diabetes Association Professional Practice Committee for Diabetes. (2026). Prevention or delay of diabetes and associated comorbidities: Standards of Care in Diabetes—2026. Diabetes Care, 49(Supplement 1), S50–S60. https://doi.org/10.2337/dc26-S003
  • Aroda, V. R., Edelstein, S. L., Goldberg, R. B., Knowler, W. C., Marcovina, S. M., Orchard, T. J., Bray, G. A., Schade, D. S., Temprosa, M. G., White, N. H., & Crandall, J. P. (2016). Long-term metformin use and Vitamin B12 deficiency in the Diabetes Prevention Program Outcomes Study. The Journal of Clinical Endocrinology & Metabolism, 101(4), 1754–1761. https://doi.org/10.1210/jc.2015-3754
  • Bauman, W. A., Shaw, S., Jayatilleke, E., Spungen, A. M., & Herbert, V. (2000). Increased intake of calcium reverses Vitamin B12 malabsorption induced by metformin. Diabetes Care, 23(9), 1227–1231. https://doi.org/10.2337/diacare.23.9.1227
  • de Jager, J., Kooy, A., Lehert, P., Wulffelé, M. G., van der Kolk, J., Bets, D., Verburg, J., Donker, A. J. M., & Stehouwer, C. D. A. (2010). Long-term treatment with metformin in patients with type 2 diabetes and risk of Vitamin B12 deficiency: A randomised placebo-controlled trial. BMJ, 340, c2181. https://doi.org/10.1136/bmj.c2181
  • Infante, M., Leoni, M., Caprio, M., & Fabbri, A. (2021). Long-term metformin therapy and Vitamin B12 deficiency: An association to bear in mind. World Journal of Diabetes, 12(7), 916–931. https://doi.org/10.4239/wjd.v12.i7.916
  • Krishnan, G. D., Zakaria, M. H., & Yahaya, N. (2020). Prevalence of Vitamin B12 deficiency and its associated factors among patients with type 2 diabetes mellitus on metformin from a district in Malaysia. Journal of the ASEAN Federation of Endocrine Societies, 35(2), 163–168. https://doi.org/10.15605/jafes.035.02.03
  • Ministry of Health Malaysia, Academy of Medicine of Malaysia, Malaysian Endocrine & Metabolic Society, Family Medicine Specialists Association of Malaysia, & Diabetes Malaysia. (2020). Clinical practice guidelines: Management of type 2 diabetes mellitus (6th ed.). https://mems.my/wp-content/uploads/2021/03/CPG-T2DM_6th-Edition-2020_210226.pdf
  • National Institute for Health and Care Excellence. (2024). Vitamin B12 deficiency in over 16s: Diagnosis and management (NICE Guideline NG239). https://www.nice.org.uk/guidance/ng239
  • National Pharmaceutical Regulatory Agency. (2024, March 4). Updated: Metformin—Risk of Vitamin B12 deficiency. Ministry of Health Malaysia. https://npra.gov.my/index.php/en/component/content/article/454-english/safety-alerts-main/safety-alerts-2024/1527576-updated-metformin-risk-of-vitamin-b12-deficiency.html?Itemid=1391
  • Ting, R. Z.-W., Szeto, C. C., Chan, M. H.-M., Ma, K. K., & Chow, K. M. (2006). Risk factors of Vitamin B12 deficiency in patients receiving metformin. Archives of Internal Medicine, 166(18), 1975–1979. https://doi.org/10.1001/archinte.166.18.1975
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