Vitamin B12 Supplementation in Diabetic Neuropathy

Vitamin B12 Supplementation in Diabetic Neuropathy :1-year Double Blind Randomized Placebo-Controlled Trial

This prospective double-blind placebo-controlled trial aims to investigate the safety and efficacy of oral dispersible tablet of vitamin B12 for 1 year, in 90 patients with diabetes mellitus type 2 and neuropathy.

In this prospective, double-blind, placebo-controlled trial, 90 patients with type 2 diabetes on metformin treatment for at least four years, and both peripheral and autonomic diabetic neuropathy were randomized to an active treatment group (n=44) receiving B12, and a control group (n=46) receiving placebo. All patients had B12 levels less than 400 pmol/L. Subjects underwent measurement of sural nerve conduction velocity and amplitude, vibration perception threshold, and performed cardiovascular autonomic reflex tests (CARTs: Mean Circular Resultant, Valsalva test, postural index and orthostatic hypotension]). Sudomotor function was assessed with the SUDOSCAN that measures electrochemical skin conductance in hands and feet. The Michigan Neuropathy Screening Instrument Questionnaire and Examination and questionnaires to evaluate quality of life and level of pain were also used.

Inclusion Criteria:

• adults (>18 years old) with Diabetes Mellitus 2
• established Diabetic neuropathy, both peripheral and autonomic (Diabetic Peripheral Neuropathy and Diabetic Autonomic Neuropathy). (Diagnosis was made with a)two or more Cardiovascular Autonomic Reflex Tests abnormal, b)abnormal nerve conduction velocity, c)abnormal Michigan Neuropathy Screening Instrument Questionnaire and Michigan Neuropathy Screening Instrument Examination ).
• good glycemic control (HbA1c between 6.5 and 7.5 %), stable in the last year before participating in the study
• metformin treatment for at least 4 years
• low vitamin B12 levels according to suggested normal values for DM2 patients over 60 years old (<400 pmol/L)

Exclusion Criteria:

• pernicious anemia,
• alcoholism
• gastrectomy
• gastric bypass surgery
• pancreatic insufficiency
• malabsorption syndromes
• chronic giardiasis
• acute infection in the last 6 months
• cardiovascular event in the last 6 months
• surgery involving small intestine or Human Immunodeficiency Virus infection.
• Patients with estimated Glomerular Filtration Rate <50 mL/min/1.73m2
• taking multivitamins or B12 supplements in the last 12 months