Metformin Use Is Not Associated With B₁₂ Deficiency or Neuropathy in Patients With Type 2 Diabetes Mellitus in Qatar

Background: Metformin may lead to B₁₂ deficiency and neuropathy. There are no published data on the prevalence of Metformin-related B₁₂ deficiency and neuropathy in the Arabian Gulf.

Aims: Determine whether Metformin intake is associated with B₁₂ deficiency and whether B₁₂ deficiency is associated with diabetic peripheral neuropathy (DPN) and painful diabetic neuropathy.

Methods: Patients with type 2 diabetes mellitus (T2DM) (n = 362) attending outpatient clinics at HMC underwent assessment of B₁₂ levels, the DN4 questionnaire, and vibration perception threshold (VPT).

Results: Comparing Metformin to non-Metformin users there were no differences in B₁₂ levels, VPT, or DN4. The prevalence of B₁₂ deficiency (B₁₂ <133 pmol/l) was lower (P < 0.01) in Metformin (8%) compared to non-Metformin (19%) users. Patients with B₁₂ deficiency had a comparable prevalence and severity of sensory neuropathy and painful neuropathy to patients without B₁₂ deficiency.

Conclusion: Serum B₁₂ levels were comparable between Metformin and non-Metformin users with T2DM in Qatar. T2DM patients on Metformin had a lower prevalence of B₁₂ deficiency. Furthermore, the prevalence and severity of neuropathy and painful diabetic neuropathy were comparable between patients with and without B₁₂ deficiency.