Metformin Use And Vitamin B12 Deficiency In Patients With Type-2 Diabetes Mellitus
Metformin is commonly used oral hypoglycaemic agent in the treatment of type-2 Diabetes Mellitus (DM). One of the important side effect of long term metformin therapy is malabsorption of vitamin B<sub>12</sub> which could lead to megaloblastic anemia and peripheral neuropathy. Therefore annual screening of serum vitamin B<sub>12</sub> level or serum methylmalonic acid (MMA)/serum homocysteine level should be done in cases taking metformin for more than four to five years with average dose of >1g per day, even in the absence of haematological or neurological abnormalities. However, as the incidence of type-2 DM is increasing, cost of annual measurement of vitamin B<sub>12</sub> level also increases. Considering cost factor for annual screening, vitamin B<sub>12</sub> supplementation appears to be more cost effective approach rather than annual screening for routine prophylaxis. Routine vitamin preparations available in the market may contain less amount of B<sub>12</sub> and hence are not of much therapeutic use in treatment of B<sub>12</sub> deficiency due to Metformin. Hence there is a need to look for higher doses of approximately 500-2000μg/day.