Efficacy of Oral Vitamin B-12 at 1000 μg Compared with 2000 μg on Neuropathic Outcomes in Patients with Diabetic Peripheral Neuropathy and Low Serum Vitamin B-12: a Randomized Clinical Trial.

Serum vitamin B-12 levels increased significantly in both groups, with a greater rise in the 2000 μg group.

• The difference in serum B-12 increase between groups was statistically significant (P = 0.049)
• Both groups started with serum vitamin B-12 levels below 200 pg/mL
• Participants were adults with T2DM, DPN, and low serum vitamin B-12
• The trial lasted 16 weeks with daily oral methylcobalamin supplementation

NRS pain scores improved significantly within both the 1000 μg and 2000 μg groups over 16 weeks.

• In the 1000 μg group, NRS scores decreased from 7.00 ± 2.03 to 5.60 ± 2.19 (P = 0.016)
• In the 2000 μg group, NRS scores decreased from 6.18 ± 2.40 to 4.42 ± 2.50 (P = 0.007)
• No significant difference in NRS outcomes was observed between the two groups

Michigan Neuropathy Screening Instrument Examination (MNSIE) scores improved significantly within both dosage groups.

• In the 1000 μg group, MNSIE scores improved from 5.70 ± 1.66 to 5.22 ± 1.99 (P = 0.033)
• In the 2000 μg group, MNSIE scores improved from 5.40 ± 1.68 to 4.47 ± 2.25 (P = 0.022)
• No significant difference in MNSIE outcomes was observed between the two groups

Neuropathy Disability Score (NDS) remained unchanged in both groups throughout the trial.

• NDS did not improve significantly in either the 1000 μg or 2000 μg group (P > 0.05 for both)
• NDS was assessed as a primary outcome alongside NRS and MNSIE

The 1000 μg dose was associated with significant improvements in hemoglobin A1c levels, whereas the 2000 μg dose was not.

• HbA1c improvement was statistically significant in the 1000 μg group
• The 2000 μg group did not show a significant improvement in HbA1c
• HbA1c was a secondary metabolic outcome measure

The 2000 μg dose was associated with a significant decline in estimated glomerular filtration rate (eGFR).

• A significant decline in eGFR was observed in the 2000 μg group
• No such decline was reported in the 1000 μg group
• eGFR was measured as part of secondary metabolic outcomes

Of 35 participants randomized, 32 completed the 16-week trial.

• Participants were randomly assigned 1:1 to receive either 1000 μg or 2000 μg of oral vitamin B-12 (methylcobalamin) daily
• Eligible participants had T2DM, DPN, and low serum vitamin B-12 levels (< 200 pg/mL)
• 3 participants did not complete the trial, leaving 32 completers