Vitamin B12 Supplementation in Diabetic Neuropathy monitored with SUDOSCAN

T. Didangelos et al.
Article title: Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial.
Nutrients 2021, 13(2), 395.

A new study on oral vitamin B12 effects in type 2 diabetes patients has been conducted by Didangelos et al, from Aristotle University of Thessaloniki, Greece. The aim of the study was to investigate the effect of normalizing vitamin B12 levels with oral B12 (methylcobalamin) 1 mg/day for one year in patients with diabetic neuropathy (DN).

Diabetic neuropathy is a serious complication of type 2 diabetes, as it can cause devastating symptoms, including unremitting and unbearable pain, and can have severe and potentially life-threatening consequences, such as the so-called “diabetic foot” that is associated with ulcers, infections, Charcot arthropathy, and amputations.

In addition to any glycemic therapy aiming at strict glycemic control, vitamin B12 (B12) has been the most commonly used supplement. The first reason is that vitamin B12 deficiency is quite common in patients with type 2 diabetes on metformin, and the second is that vitamin B12 deficiency may cause neurological disorders, such as peripheral, autonomic (including cardiovascular), and painful neuropathy, accelerating the progression of diabetic neuropathy.

The American Diabetes Association (ADA) therefore recommends that in patients with diabetic neuropathy on metformin therapy, vitamin B12 levels should be regularly monitored on an annual basis.

In this study 90 type 2 diabetes patients well balanced due to metformin for at least four years and with both peripheral and autonomic diabetic neuropathy have been enrolled in a double-blind placebo-controlled trial and randomized to an active treatment group (n = 44) receiving B12 and a control group (n = 46) receiving a placebo.

Several tests were conducted to evaluate neurophysiological parameters, sudomotor function (autonomic dysfunction) measured with SUDOSCAN, pain score, and quality of life.

After 12 months with oral B12 supplementation in type 2 diabetes patients with diabetic neuropathy there were increased plasma B12 levels and significant improvement of all neurophysiological parameters, sudomotor function (SUDOSCAN’s Electrochemical Skin Conductance), pain score, and quality of life. See Table 1.

“SUDOSCAN may be a reliable and early detector of small fiber neuropathy, in addition to diabetic peripheral neuropathy (DPN) and sudomotor dysfunction, all of which are critical factors for the development of the “diabetic foot””.

Table 1: Changes in indices from baseline to follow-up in both groups.
a For difference during follow-up in the active group; b for difference during follow-up in the placebo group; c for difference between groups adjusted for HbA1c and antidiabetic medication.
Abbreviations: HbA1c: glycated hemoglobin; MNSIQ: Michigan Neuropathy Screening Instrument Questionnaire; MNSIE: Michigan Neuropathy Screening Instrument Examination; DQoL: Diabetes Quality of Life Questionnaire; SNAP: sural nerve action potential (amplitude); SNCV: sural sensory nerve conduction velocity; VPT: vibration perception threshold; MCR: mean circular resultant; PI: postural index; Postural hypotension: PO (orthostatic hypotension); Pain: pain score questionnaire; ESCF: electrochemical skin conductance in feet; ESCH: electrochemical skin conductance in hands.

Keywords: diabetic neuropathy; vitamin B12; SUDOSCAN; metformin; diabetic foot; diabetes mellitus; autonomic neuropathy; painful neuropathy.

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