What causes type 2 diabetes?

The answer is more complex than most people think. Researcher Dr. Gillian Booth and her team are hard at work uncovering some of those answers

By Gabrielle Bauer

What causes type 2 diabetes: genes, diet, activity level? All three? Dr. Gillian Booth, an endocrinologist and scientist in the Centre for Urban Health Solutions at the Li Ka Shing Knowledge Institute of St. Michael’s Hospital in Toronto, has been exploring another cause: where you live. Her research, which has been funded by Diabetes Canada (formerly Canadian Diabetes Association), has linked “walkability”—how well a neighbourhood supports walking, cycling, and keeping the car in the garage— to lower rates of obesity and type 2 diabetes.

“Type 2 diabetes is a complex problem with roots in genetics, the environment and individual behavioural choices,” says Dr. Jan Hux, President and CEO of Diabetes Canada. “A second, less appreciated contributor to the growing diabetes epidemic is the role of the environment, specifically factors such as the walkability of neighbourhoods, food security and local access to health-related facilities and services.”

Why does where you live matter?

In a Toronto Diabetes Atlas entitled, “Neighbourhood Environments and Resources for Healthy Living—A Focus on Diabetes in Toronto,” Booth and her team put together statistics of 140 neighbourhoods in Toronto. In some suburbs, they found rates of diabetes two to three times higher than the norm. Income and ethnic background, while undoubtedly playing a role, “didn’t fully account for the differences in diabetes rates across neighbourhoods,” she says. “Although diabetes can be prevented through physical activity, healthy eating and weight loss, we suspected that the environment in which one lives is also an important indicator of one’s risk.” Further research in this area by Dr. Booth and her team determined that this was indeed the case.

In 2016, she and her colleagues published a related study called “Association of Neighborhood Walkability with Change in Overweight, Obesity, and Diabetes” in the Journal of the American Medical Association (JAMA), which was selected by the American Heart Association’s Lifestyle and Cardiometabolic Health Council as “one of the most impactful papers of 2016.” The study looked at these various factors over a 12-year period in 15 municipalities in Southern Ontario, further building on and supporting the findings that they have previously reported.

While overall rates of obesity have been increasing, Booth says they have remained stable in the most walkable areas—such as the Beach neighbourhood of Toronto. Furthermore, these highly walkable communities had a decline in the number of new cases of diabetes in the population each year. She herself lives in a walkable urban neighbourhood, and either walks or takes public transit to work. “Driving doesn’t actually get you places faster when you’re downtown,” she adds.

What can be done to help Canadians live healthier lives?

“For people who are at risk of developing diabetes, behavioural choices that promote obesity increase that risk,” says Hux. ”Improving the diet and physical activity level of persons at high risk has been shown to reduce the risk by nearly 60 per cent.”

Urban planners who are involved in designing cities have been looking at Booth’s findings. For example, in the Region of Peel in Ontario—an area with especially high rates of diabetes—“is now taking a population health perspective when reviewing development submissions,” she says. Booth has been part of meetings between provincial health, planning, and transportation officials to create policy changes that promote walkability. “It’s not a revolution,” she says modestly, “but there’s a lot of movement in the area.” A well-chosen word indeed.

Learn more about the new Canadian Diabetes Prevention Program launched by Diabetes Canada and LMC.