A cross sectional study to estimate the prevalence of vitamin B12 deficiency among type 2 diabetes cases on metformin therapy: a one year study

Veeranarayana Gundu, Venkata Subrahmanyam Chintha


Background: Type 2 diabetes mellitus is associated with long term neurological complications. Metformin usage as first line drug for longer duration is associated with Vitamin B12 deficiency. Metformin on longer usage is associated with B12 deficiency in various studies and prevalence is variable. The study aims to estimate the prevalence of Vitamin B12 deficiency and its associated risk factors among T2DM on metformin therapy.

Methods: A cross sectional study for one year was conducted at Narayana Medical college a tertiary care hospital. All T2DM cases attending the department and on Metformin usage were enrolled and data of age, sex, duration of T2DM, dosage of Metformin were noted as variables. Levels of Hb1Ac and complete blood picture were noted. Statistical analysis was conducted by Statistical package for social sciences (SPSS) version 21 v and p<0.05 was considered statistically significant.

Results: A total of 258 participants were enrolled of which 68 (26.36%) were B12 deficient, 46 cases (17.83%) moderately deficient and 144 (55.81%) were normal. Prevalence of Vitamin B12 in the study was 26.36%. There was a statistically significant association between Vitamin B12 levels and daily dose of metformin usage. (p>0.005)

Conclusions: Our study clearly highlighted the association of Vitamin B12 deficiency among T2DM on metformin therapy. Prevalence of Vitamin B12 deficiency among T2DM patients on metformin is quite considerable and cannot be neglected. Physicians prescribing the drug should plan inclusion Vitamin B12 supplementation as regular drug in T2DM cases.


Type 2 diabetes mellitus, Metformin, B12 deficiency, Prevalence

Full Text:



Sen A. Health: perception versus observation. BMJ. 2002;324(7342):860-1.

Are S, Deshmukh S, Kulkarni M. Prevalence of type 2 diabetes mellitus (T2DM) in India: A systematic review (1994–2018). Diabetes & Metabolic Syndrome: Clinical Research & Reviews. 2020;1(5):897-906.

American Diabetes Association: Summary of revisions to the 2011 clinical practice recommendations. Diabetes Care. 2011;34(Suppl 1):S3.

Wei Ting RZ, Szeto CC, Chan M, Ma K. Risk Factors of Vitamin B12 Deficiency in Patients Receiving Metformin. Arch Intern Med. 2006;166:1975-9.

Hendrawati YD, Andrajati R, Supardi S, Ariyani A. The risk of cobalamin deficiency symptoms related to long-term metformin use in T2DM patients. Acta Endocrinol (Buchar). 2018;14:49-54.

World Health Organization. Iron deficiency anemia: assessment, prevention, and control. United States: World Health Organization; 2001. Available at: ida_assessment_prevention_control.pdf. Accessed on 23rd December, 2015.

Yetley EA, Pfeiffer CM, Phinney KW, Bailey RL, Blackmore S, Bock JL, et al. Biomarkers of vitamin B-12 status in NHANES: A roundtable summary. Am J Clin Nutr. 2011;94:S313-21.

Marar O, Senturk S, Agha A, Thompson C, Smith D. Prevalence of Vitamin B12 deficiency in patients with type 2 diabetes mellitus on metformin. Royal Coll Surg Ireland Student Med J. 2011;4(1):16-20.

Pflipsen MC, Oh RC, Saguil A, Seehusen DA, Topolski R. The prevalence of vitamin B12 deficiency in patients with type 2 diabetes, a cross sectional study. J Am Board Fam Med. 2009;22(5):528-34.

Wong CW, Leung CS, Leung CP, Cheng JN. Association of metformin use with vitamin B12 deficiency in the institutionalized elderly. Arch Gerontol Geriatr. 2018;79:57-62.

Ahmed MA, Muntingh G, Rheeder P. Vitamin B12 deficiency in metformin treated type-2 diabetes patients, prevalence and association with peripheral neuropathy. BMC Pharmacol Toxicol. 2016;17(1):44.

Avares Bello C, Capitão RM, Sequeira Duarte J, Azinheira J, Vasconcelos C. Défice de Vitamina B12 na Diabetes Mellitus Tipo 2 [Vitamin B12 Deficiency in Type 2 Diabetes Mellitus]. Acta Med Port. 2017;30(10):719-26.

Aroda VR, Edelstein SL, Goldberg RB, Knowler WC, Marcovina SM, Orchard TJ, et al. Long-term metformin use and vitamin B12 deficiency in the Diabetes Prevention Program Outcomes Study. J Clin Endocrinol Metab. 2016;101:1754-61.