The Journal of the American Board of Family Medicine September-October 2009 22 (5): 528-534 (2009) © 2009 American Board of Family Medicine
The Prevalence of Vitamin B12 Deficiency in Patients with Type 2 Diabetes: A Cross-Sectional Study. Matthew C. Pflipsen, MD, Robert C. Oh, MD, MPH, Aaron Saguil, MD, MPH, Dean A. Seehusen, MD, MPH, FAAFP and Richard Topolski, PhD.
Methods: We conducted a cross-sectional study of 203 outpatient  type 2 diabetic patients at a large military primary care clinic.  Patients completed a survey and had B12 levels measured.  Patients with borderline B12 levels also had methylmalonic  acid and homocysteine levels drawn. Serum B12 levels  <100 pg/mL or serum B12 levels of 100 to 350 pg/mL with  elevation of serum methylmalonic acid >243 nmol/L or homocysteine  >11.9 nmol/L defined B12 deficiency. Descriptive  statistics described frequency and means. 2 and student's  t tests were used to analyze associations between categorical  and continuous variables, respectively. Multivariate logistical  regression identified covariates independently associated with  B12 deficiency.  
Results: Twenty-two percent (n = 44) of diabetic patients had metabolically confirmed B12 deficiency. Patients on metformin had lower serum B12 levels (425.99 pg/mL vs 527.49 pg/mL; P = .012) and were at increased risk for B12 deficiency (P = .04), as defined by a serum B12 level <350 pg/mL. Prevalence of B12 deficiency was significantly lower for patients using a multivitamin (odds ratio, 0.31; 95% CI, 0.150.63).
Conclusions: Our results found a 22% prevalence of metabolically confirmed B12 deficiency in the primary care type 2 diabetic population. Although further research needs to be performed to determine the clinical implications of our findings, B12 deficiency should be considered in type 2 diabetic patients, especially those taking metformin. Furthermore, a daily multivitamin may protect against B12 deficiency.
 
