Mymensingh Med J. 2021 Oct;30(4):913-920.
ABSTRACT
Peripheral neuropathy caused by diabetes mellitus (DM) and vitamin B12 deficiency may produce overlapping clinical pictures. Metformin use is a known cause of B12 deficiency in patients with type 2 DM (T2DM). This cross-sectional comparative study was conducted at two specialized endocrine outpatient clinics in Mymensingh and Cumilla cities of Bangladesh over one year from July 2019 to June 2020. Non-pregnant adults (≥18 years of age) receiving drug treatment for T2DM for at least six months were included in this study. The study subjects were divided into two groups: those with ongoing treatment with metformin and those who never received metformin in their lifetime. Out of 99 subjects evaluated, 66 (66.7%) were in the metformin group, and 33 (33.3%) were in the non-metformin group. Subjects in the metformin group had significantly lower B12 levels compared to the non-metformin group [448.5 (343.0-570.9) vs. 549.0 (487.5-847.0) pg/mL, median (IQR), p<0.001]. None of the study subjects in the non-metformin group were either borderline deficient or deficient of B12 compared to five borderline deficient and three deficient subjects in the metformin group. Among the study subjects, 88.9% had peripheral neuropathy (PN) (43.4% mild, 21.2% moderate and 24.2% severe PN); the two groups had similar frequencies of PN. Though median serum B12 levels were lower in mild [483.0 (411.2-620.0) pg/mL], moderate [492.0 (366.5-680.0) pg/mL] and severe PN [524.5 (363.5-654.2) pg/mL] groups compared to absent PN group [540.0 (340.0-685.0) pg/mL]; the difference in B12 levels across the four groups was not statistically significant. B12 levels had weak negative correlation (r = -0.061, p = 0.624) with gram-years of metformin use. Periodic screening for serum vitamin B12 levels should be done to identify metformin-induced B12 deficiency in T2DM, especially those with PN.
PMID:34605456
