Abstract:
ABSTRACT
Introduction: Metformin is the most widely administered anti-diabetic medication among
type 2 diabetes mellitus (T2DM) patients. However, metformin induces vitamin B12 malabsorption
which may increase the risk of vitamin B12 deficiency among T2DM patients. We
determined the prevalence of vitamin B12 deficiency and related risk factors among Ghanaian
T2DM patients on metformin therapy.
Methods: This cross-sectional study recruited 196 T2DM patients attending the outpatient
diabetic clinic at the Effia Nkwanta Regional Hospital, Ghana. Fasting venous blood was
collected for biochemical analysis. Vitamin B12 deficiency was defined as serum B12 <100
pg/ml and methylmalonic acid (MMA) ≥ 0.4μmol/L.
Results: The prevalence of vitamin B12 deficiency based on serum vitamin B12, MMA, and the
combination of both methods were 32.1%, 14.8%, and 14.3%, respectively. Longer duration of
metformin use [5-9 years; aOR= 2.83, 95% CI (1.03-7.81), p=0.045 and ≥10 years; aOR= 4.17,
95% CI (1.41-12.33), p=0.010], higher daily dose of metformin [1000-2000 mg/day; aOR= 1.34,
95% CI (0.25-2.74), p=0.038 and >2000 mg/day; aOR= 1.13, 95% CI (0.39-2.97), p=0.047], and
very high body fat [aOR= 2.98, 95% CI (1.47-6.05), p=0.020] were significantly associated with
increased odds of vitamin B12 deficiency. For daily dose of metformin, a cutoff value of 1500
mg/day presented with a sensitivity, specificity, and AUC of 71.4%, 40.1%, and 0.54 (95% CI,
0.53-0.54), respectively, in predicting vitamin B12 deficiency. A ≥ six (6) years duration of
metformin therapy presented with a sensitivity, specificity, and AUC of 70.4%, 62.9%, and 0.66
(95% CI, 0.57-0.75), respectively, in predicting vitamin B12 deficiency.
Conclusion: Vitamin B12 deficiency is high among T2DM patients on metformin therapy in
Ghana. There is the need for regular monitoring of vitamin B12 levels especially in T2DM
patients on metformin daily dose of ≥ 1500 mg for duration of therapy ≥ 6 years.
