Pseudo-dementia caused by metformin-induced vitamin B12 deficiency.

Metformin is the most widely used oral insulin-sensitizing agent. There is a significant association between long-term metformin therapy and an increased prevalence of vitamin B12 deficiency. Vitamin B12 deficiency is one of the causes of pseudo-dementia. This paper presents a rare case of pseudo-dementia in a 60-year-old Caucasian woman caused by vitamin B12 deficiency induced by the use of metformin, a vegetarian diet, and smoking. In diabetics with cognitive disorders who are on biguanide therapy, it is necessary to determine the level of vitamin B12 in the serum in order to rule out possible pseudo-dementia and to avoid possible hematological and neurological disorders. Unfortunately, vitamin B12 deficiency remains frequently unrecognized in those patients.