Vitamin B12 Supplementation in Diabetic Neuropathy

by | Nov 2, 2023 | 2021, Diabetes, Vitamin B12, Vitamins

Written by Harold Oster, MD. Results suggest that supplementation with vitamin B12 in patients with diabetic neuropathy and low b12 levels improves pain, quality of life, and results of neurophysiologic testing.

vitamins B12It is estimated that over 400 million people worldwide have diabetes. Approximately 50% of diabetics will develop neuropathy in their lifetime. The most common form is peripheral sensory neuropathy, characterized by pain and lack of sensation, which can lead to ulcers, infections, arthropathy, and loss of limbs1. Autonomic neuropathy, which commonly affects the cardiovascular and gastrointestinal systems, can be debilitating2. Deficiency in vitamin B12 can lead to peripheral neuropathy, among other neurologic conditions3. Over twenty-five percent of diabetics have insufficient levels of vitamin B12, and taking metformin increases the risk4.

Triantafyllos Didangelos et al. studied the effects of supplementation with 1000 mcg of vitamin B12 (methylcobalamin) in adult diabetics with neuropathy and insufficient levels of vitamin B12. Ninety patients were enrolled. All participants had established peripheral and autonomic neuropathy, were taking metformin, had hemoglobin A1c levels between 6.5% and 7.5%, and had levels of vitamin B12 less than 400 pmol/L. Participants were randomly given tablets containing 1000mcg of methylcobalamin or a placebo to take daily for 12 months. Patients were evaluated for demographic factors, past medical history, blood pressure, and anthropometric measures. At baseline and the end of the study, blood was tested for lipids, hemoglobin A1c, vitamin B12 levels, complete blood count, and routine chemistries. At baseline and 12 months, participants were evaluated for autonomic and peripheral neuropathy with numerous validated tests: SUDOSCAN for electrochemical skin conductance, cardiovascular autonomic reflex tests, DPN-Check for sural nerve function, vibration perception threshold, and the Michigan Neuropathy Screening Instrument (MNSI), which includes a questionnaire (MNSIQ) and examination (MNSIE)5,6. Quality of life (QOL) was assessed with the Diabetes Quality of Life Brief Clinical Inventory7. Neuropathic pain was evaluated with the painDetect questionnaire8.

The authors noted the following:

  • All ninety participants completed the study.
  • There were no significant differences at baseline in demographics, anthropometric measures, blood tests, or neurologic testing between the vitamin B12 supplementation and placebo groups.
  • Serum B12 levels increased in the active group from an average of 232.0 pmol/L to 776.7 pmol/L. Levels did not significantly change in the placebo group.
  • After 12 months, the vibration perception threshold, MNSIQ, quality of life, pain score, sural nerve function, and electrochemical skin conductance improved in the active group but not the placebo group.
  • The cardiovascular autonomic reflex tests and the MNSIE did not improve in either group.
  • MNSIQ, sural nerve function, and the mean circular resultant, a component of CARTs that measures heart rate variability9, significantly worsened in the placebo group.
  • Blood pressure, diabetes control, and the other blood tests did not differ significantly between the active and placebo groups.

Results suggest that in diabetics with neuropathy and low vitamin B12 levels, daily supplementation with 1000mcg of vitamin B12 improves pain, quality of life, and results of neurophysiologic tests. Limitations of the study were that all participants were Caucasian and enrolled from a single diabetes center.

Source: Didangelos, Triantafyllos, Eleni Karlafti, Evangelia Kotzakioulafi, Eleni Margariti, Parthena Giannoulaki, Georgios Batanis, Solomon Tesfaye, and Kοnstantinos Kantartzis. “Vitamin B12 supplementation in diabetic neuropathy: a 1-year, randomized, double-blind, placebo-controlled trial.” Nutrients 13, no. 2 (2021): 395.

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

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Posted November 2, 2023.

Harold Oster, MD graduated from medical school in Miami, Florida in 1992 and moved to Minnesota in 2004. After more than 25 years of practicing Internal Medicine, he recently retired. Dr. Oster is especially interested in nutrition, weight management, and disease prevention. Visit his website at haroldoster.com.

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