(NaturalNews) Long-term use of the popular diabetes drug metformin
(originally marketed as Glucophage) may cause patients to develop a steadily
worsening vitamin B12 deficiency, Dutch scientists have found.
"Our study shows that this decrease is not a transitory phenomenon, but persists
and grows over time," wrote the Maastricht University Medical Center researchers
in the British Medical Journal.
This is an issue of particular concern given the prevalence of diabetes and the
popularity of metformin as a treatment.
"Metformin is considered
a cornerstone in the
treatment of diabetes and is the most frequently prescribed first line
therapy for individuals with type 2
diabetes," the
researchers wrote. "In addition, it is one of a few ... associated with
improvements in cardiovascular morbidity and mortality, which is a major cause
of death in patients with
type 2 diabetes."
Earlier, short-term studies had found that use of the
drug might lead to
insufficient levels of the vitamin in the body. The new study confirmed this
trend over the long term.
"Metformin does ... induce
vitamin B12 malabsorption, which may increase the
risk of developing vitamin
B12 deficiency -- a
clinically important and treatable condition," the researchers wrote.
The researchers assigned 390
Type 2 diabetes
patients at the outpatient clinics of three nonacademic hospitals to take either
metformin or a placebo
pill three times per day for more than four years. The average study participant
had been diagnosed with diabetes 13 years prior and had been undergoing
insulin treatment for
seven years. Average participant age was 61.
Among those taking metformin, vitamin B12 levels began to steadily drop relative
to those who were taking a placebo pill. The biggest drop occurred in the first
few months, but the decrease continued over the course of the study.
After four years, participants in the metformin group had undergone a 19 percent
relative reduction in their levels of the nutrient. They were 11.2 percent more
likely than placebo participants to suffer from B12 insufficiency and 7.2
percent more likely to suffer from deficiency.
For every 8.9 patients treated with metformin, one would develop insufficient
vitamin B12 levels. This increased risk remained after researchers adjusted for
other risk factors including age, duration of diabetes, insulin dose, sex,
smoking status and previous treatment with metformin.
"Our study shows that it is reasonable to assume harm will eventually occur in
some patients with metformin-induced low vitamin B12 levels," the researchers
wrote.
The researchers found that metformin seems to inhibit the intestine's absorption
of vitamin B12. Fortunately, calcium supplements appear to reverse this effect.
Vitamin B12 is critical for maintaining nerve and red blood cell health. It can
be found in animal products, nutritional yeast and fortified breakfast cereals.
Symptoms of deficiency include anemia, fatigue, nerve damage and cognitive
changes. Because similar
symptoms often occur in diabetics and the elderly, deficiency may be hard to
detect in such populations. Yet while B12 deficiency can carry severe
consequences, it is relatively easy to correct with supplementation.
The researchers suggested that all patients taking metformin have their vitamin
B12 levels tested regularly to avoid potentially severe consequences.
"Vitamin B-12 deficiency is preventable; therefore, our findings suggest that
regular measurement of
vitamin B-12 concentrations during long-term metformin treatment should be
strongly considered." the researchers wrote.
Nearly 11 percent of the U.S. population, or 24 million people, suffer from
diabetes. Of these 5.7 million are undiagnosed. In addition, 57 million people
in the United States alone are estimated to be pre-diabetic, or at imminent risk
of developing the disease.
Worldwide, an estimated 246 million people suffer from the disease. Prevalence
is only expected to increase as the spreading Western diet and lifestyle
lead to increasing rates of
obesity.
Sources for this story include:
http://www.reuters.com/article/idUS...
http://www.medscape.com/viewarticle...
http://www.medpagetoday.com/Endocri....