Vitamin B12 deficiency seen in many metformin users
October 19, 2006 11:01:12 AM PST
Although treatment with the anti-diabetes drug metformin has greatly
improved the prognosis of adults with type 2 diabetes, it appears to be
associated with an increased risk of vitamin B12 deficiency, Chinese
researchers report.
Lack of vitamin B12, if unrecognized, causes nervous system damage.
"Because this condition is treatable, and predictable as suggested by
our research, enough concerns exist to call attention to the value of
vitamin B12 screening, particularly among at-risk patients receiving
metformin," senior investigator Dr. Kai Ming Chow told Reuters Health.
"Reports of metformin-related vitamin B12 deficiency have caused us to
question whether this adverse effect is predictable among patients with
type 2 diabetes who receive metformin," Chow said.
To investigate, Chow of the Chinese University of Hong Kong and
colleagues conducted a case-control study involving 155 patients with
diabetes and metformin-related vitamin B12 deficiency. Another 310
similar patients who did not have low vitamin B12 while taking metformin
acted as controls.
After adjustment for many potential confounders, the risk of vitamin B12
deficiency increased with current dose and duration of metformin, the
researchers found.
Each 1-gram daily metformin dose increment, said Chow, "conferred a
twofold risk — adjusted odds ratio of 2.88 — for developing vitamin
B12 deficiency."
In addition, with metformin use for 3 years or more, "there will be a
twofold increased chance of metformin-associated vitamin B12 deficiency
— adjusted odds ratio 2.39."
Current data, Chow concluded, underscores the need for monitoring
vitamin B12 status among people taking high dose or prolonged courses of
metformin.