Prevalence and determinants of Vitamin B12 deficiency among subjects with Type 2 Diabetes in a tertiary institution in Southeast Nigeria

Vitamin B12 (Vit B12) deficiency is very common among diabetic subjects, although with variable prevalence. The aim of this study is to determine the prevalence of Vit B12 deficiency and its associated factors among patients with Diabetes Mellitus (DM). This study is important because Vit B12 deficiency is associated with metformin, which is a bedrock in the management of diabetic subjects. Since peripheral neuropathy is a recognized complication of DM, and also occurs in Vit B12 deficiency, it would be important to ascertain the role of Vit B12 deficiency in the emergence of peripheral neuropathy. Appropriate measures like vitamin supplementation would then be instituted in diabetics who are on metformin. A cross-sectional study was conducted at Enugu State University Teaching Hospital in Enugu, Nigeria, between January to July 2019. A total of 422 patients who fit the eligibility criteria were included in the study. Data on demographics, medication use, and anthropometry were obtained from each subject, while blood was drawn to study Vit B12 levels, Haemoglobin (Hb), Mean Cell Volume (MCV), and Glycated Heamoglobin (HbA1c). Vitamin B12 deficiency was defined as serum B12 level of ≤200 pg/mL. The prevalence of vitamin B12 deficiency among Type 2 DM patients was 16.6% (n=364). Predictors of Vit B12 deficiency in Type 2 diabetic subjects included duration of metformin use of more than five years (p<0.0001). Other predictors of vitamin B12 deficiency include Body Mass Index (BMI), diabetes duration, and macrocytic anemia. This study suggests that the prevalence of Vit B12 deficiency among patients with DM in our population is substantial. This is more frequent among patients who have been on metformin for more than five years.