Metformin induces reductions in plasma cobalamin and haptocorrin bound cobalamin levels in elderly diabetic patients.

ABSTRACT

OBJECTIVE: To study the effect of short term metformin therapy on plasma levels of cobalamin, cobalamin related metabolites and cobalamin binding proteins in elderly patients. DESIGN AND METHODS: Twenty patients with type 2 diabetes were assigned to receive metformin or not for 3 months. Cobalamin and its metabolites were measured before and after metformin therapy. RESULTS: As compared to baseline measures, there was a metformin therapy specific significant decrease in plasma levels of total cobalamin, total haptocorrin and haptocorrin bound cobalamin. CONCLUSIONS: Plasma total cobalamin and haptocorrin bound cobalamin levels are reduced by short term metformin therapy in an elderly diabetic population. Larger scale, longer term studies are necessary to determine if there is an unequivocal decrease in functional measures of cobalamin status.