Variations in Serum Vitamin B12 Levels among Metformin Receiving and Non-Receiving Type 2 Diabetes Mellitus Patients - A Case Control Study in a Tertiary Care Hospital in Puducherry

Author(s): Priyadharshini Kannan1, Sivaa Rajendran2, Sunil Kumar Nanda3, Vasanthi Natarajan4

Metformin is considered as a cornerstone in the treatment of diabetes and is the
most frequently prescribed first line therapy for individuals with T2DM. Metformin
use in type 2 diabetes mellitus has shown to cause vitamin B12 (B12) deficiency.
Besides these, B12 deficiency related neuropathy may mimic and/or aggravate the
underlying diabetic neuropathy. Furthermore, there have been lack of consensus
regarding the universal routine screening of serum B12 levels among metformin
users with T2DM, and similar studies from India are also limited. So, we wanted
to study the relationship between metformin use and serum B12 in T2DM patients.
The study included a total of 104 subjects of which 52 are T2DM affected
individuals who are only on metformin therapy for at least 3 months, served as
cases and 52 are newly diagnosed T2DM age and sex matched individuals yet to
be medically treated, served as controls. Their blood samples were collected to
estimate vitamin B12 and other parameters.
The median B12 levels in cases 213.5 pg/mL (IQR 136.25-301.0) were found to
be significantly lower (P < 0.05) when compared to median levels of controls 240
pg/mL (IQR 214-303.25). B12 levels also showed a significant fall in their levels
with increasing duration of T2DM.
Metformin induced vitamin B12 deficiency plays a major role in developing life risks
in T2DM patients. Routine screening and supplementation of B12 may be required
in T2DM patients