McMaster scientists unlock the secrets of a common diabetes drug

morgan and greg

Two McMaster researchers have unlocked the mystery of how metformin works.


More than 120 million people around the world suffer from Type 2 diabetes, including two million in Canada. Many take the drug metformin to help control the disease.

Doctors know metformin needs to interact with insulin to be effective, and that it can’t lower blood sugar on its own. No one has been able to explain how and why this happens.

Until now.

Two researchers at McMaster, Greg Steinberg and Morgan Fullerton, are the first to unlock that mystery with the discovery that metformin works on fat in the liver. Their research was published Monday in the journal Nature Medicine.

“The key is that metformin doesn’t work to lower blood glucose by directly working on the glucose. It works on reducing harmful fat molecules in the liver, which then allows insulin to work better and lower blood sugar levels,” said Steinberg, associate professor in the Department of Medicine at the Michael G. DeGroote School of Medicine.

Steinberg also holds the Canada Research Chair in Metabolism and Obesity, and is a co-director of the Metabolism and Childhood (MAC)-Obesity Research Program. His research team included scientists in Alberta, Australia and Scotland.

He explained that most people taking metformin have a fatty liver, which is frequently caused by obesity.

“Fat is likely a key trigger for pre-diabetes, causing blood sugar to start going up because insulin can’t work as efficiently to stop sugar coming from the liver,” said Steinberg.

The discovery offers a huge head start in finding combination therapies (and more personalized approaches) for diabetics for whom metformin isn’t enough to restore their blood sugar to normal levels.

Steinberg’s team at McMaster was supported by grants and fellowships from the Canadian Institutes for Health Research and the Canadian Diabetes Association.