Prevalence of vitamin B12 deficiency in patients with type 2 diabetes taking metformin: a developing country perspective

Objective: To determine the prevalence of vitamin B12 deficiency in patients with type 2 diabetes taking metformin attending a tertiary care facility. Methodology: This cross-sectional study was conducted at Diabetic OPD, Civil Hospital, Karachi, from January 2012 to July 2012. Patients of 35 to 60 years of age with type 2 Diabetes Mellitus (DM) and compliant with metformin (? 500 mg/day) for more than 3 years were included. Patients with partial or total gastrectomy, pernicious anemia, Crohn's disease, on supplemental vitamin B12, and strict vegetarians were excluded. Brief history regarding the duration of DM, duration of metformin use, daily dose of metformin, mean blood sugar levels and monthly family income was taken. One blood sample from each patient was obtained to determine vitamin B12 level. Vitamin B12 deficiency was defined as serum level <125 pmol/L. The data were analyzed using SPSS version 19. Results: Out of 155 patients enrolled, 84 (54.2%) were male and 71 (45.8%) were female. The vitamin B12 deficiency was found in 53 (34.2%) cases. Of these, 31 (58.49%) patients were >50 years of age, 16 (30.1%) were 40-50 years of age and 6 (11.30%) were <40 years of age (p=0.01); 29 (54.71%) patients were male and 24 (45.28%) were female (p=0.53); 34 (64.15%) patients had duration of DM <7 years and 19 (35.84%) had duration >7 years (p=0.05). 18 (33.96%) patients were taking dose between 1000-2000 mg and 35 (66.03%) were taking dose of >2000 mg (p<0.001); 36 (67.92%) patients were complaint to metformin and 17 (32.07%) patients were noncompliant (p=0.20). Conclusions: Vitamin B12 deficiency is prevalent in patients with type 2 DM taking metformin and they should be investigated for vitamin B12 deficiency.