Cobalamin status and its relation with depression, cognition and neuropathy in patients with type 2 diabetes mellitus using metformin.

Aims: To investigate the associations of vitamin B12 (cobalamin and holotranscobalamin) status with depression, cognition and neuropathy in patients with type 2 diabetes using metformin.

Methods: In an observational study, among 550 type 2 diabetes patients using metformin, cobalamin and holotranscobalamin (holoTCII) levels were measured at the annual diabetes checkup, and deficiencies were defined as <148 and <21 pmol/L, respectively. Depression and cognitive function were assessed with corresponding International Classification of Primary Care codes and questionnaires; neuropathy with medical record data and a questionnaire.