Common diabetes drug metformin may alter metal amounts in blood, study finds

Metformin, a commonly prescribed anti-diabetic drug, could impact metal levels in blood by significantly lowering copper and iron and spiking zinc amounts, possibly related to preventing complications, according to a study.

The drug helps one manage diabetes by lowering blood sugar levels.

The findings, published in the British Medical Journal (BMJ) Open Diabetes Research and Care, are an important step in understanding how the common anti-diabetes drug works, researchers said.

“It is significant that we could show this in humans. Furthermore, since decreases in copper and iron concentrations and an increase in zinc concentration are all considered to be associated with improved glucose tolerance and prevention of complications, these changes may indeed be related to metformin’s action,” author Wataru Ogawa, an endocrinologist and professor at Japan’s Kobe University, said.

Among nearly 200 diabetes patients at the at Kobe University Hospital—half of whom took metformin for at least six months and half did not—samples of blood serum were analysed for copper, iron and zinc, along with substances that might indicate metal deficiency.

“Metformin users showed significantly lower serum copper and iron levels, and higher zinc levels, compared to the non-users,” the authors wrote.

Further, the lowered copper and iron measures were found to be in line with deficiencies of the metals.

The changes in metal amounts in blood could be related to the effects produced in the body due to metformin, which also include benefits such as action against tumours and inflammation, the authors added.

“It is known that diabetes patients experience changes in the blood levels of metals such as copper, iron and zinc. In addition, chemical studies found that metformin has the ability to bind certain metals, such as copper, and recent studies showed that it is this binding ability that might be responsible for some of the drug’s beneficial effects,” Ogawa said.

“So, we wanted to know whether metformin actually affects blood metal levels in humans, which had not been clarified,” the author said.

Clinical trials and experiments in animals are needed to discern cause-and-effect links between how metformin works and the effects it produces, findings from which could help in developing new drugs, the team said.