Learning What a Common Diabetes Drug Does to a Freshwater Lake

Metformin is a drug that is commonly prescribed in North America to treat type 2 diabetes.

In 2015, 80 million prescriptions were filled out for metformin in the United States alone. Currently in Canada, 30 percent of Indigenous adults suffer from type 2 diabetes.

Metformin is not broken down in the human body, so an estimated 70 percent is excreted in urine and feces as the active pharmaceutical. The breakdown product, guanylurea, has also been shown to be metabolically active. While the fate and effects of metformin and guanylurea in the environment are not fully understood, some preliminary lab tests show inhibited growth and reproduction in fish exposed to concentrations seen in the environment.

During the summer of 2019, researchers at IISD Experimental Lakes Area will explore what happens when metformin is introduced into freshwater environments. Using small limnocorrals, we will conduct regular monitoring to learn how metformin impacts all levels of the food web, from microinvertebrates to fish.

This research is being carried out in collaboration with the Environment and Climate Change Canada, McMaster University, the School of Freshwater Sciences at the University of Wisconsin–Milwaukee, and the Alaska Department of Health and Social Services.