For years, Canadians have heard that obesity, a lack of physical activity and a family history are the top risk factors for developing Type 2 diabetes.

But new Canadian research says that, in fact, it is living in poverty that can double or even triple the likelihood of developing the disease.

"What we know about Type 2 diabetes is not only are low-income and poor people more likely to get it, but they're also the ones that, once they get it, are much more likely to suffer complications," Prof. Dennis Raphael, one of the researchers, told in a telephone interview.

"And the complications from Type 2 diabetes when they're bad are really bad, whether it's amputations, or blindness, or cardiovascular disease."

Researchers from York University analyzed two sets of data: the Canadian Community Health Survey (CCHS) and the National Population Health Survey (NPHS) for a study published in the journal Health Policy.

The first set of data showed that for men, being in the lowest-income category (earning less than $15,000 per year), doubles the risk of developing Type 2 diabetes compared to being in one of the highest-income brackets (earning more than $80,000 per year). The risk remains the same when other risk factors are taken into account, such as education, body mass index and physical activity levels.

The findings are even more striking for women in the lowest-income category. For them, the risk of developing type 2 diabetes is more than triple the risk of women in the highest-income category. When education, body mass index and physical activity levels are taken into account, the risk is still well more than double.

Results from the NPHS analysis are just as striking. Researchers found that living in poverty in the two years prior to diagnosis increased the risk of developing Type 2 diabetes by 24 per cent, a risk not changed when factoring in weight or physical activity. Living in poverty at any time increased the risk by 26 per cent.

Generally speaking, subjects who lived more often in poverty during the 12-year study period had a 41 per cent greater chance of developing the disease. When obesity and physical activity levels were taken into account, the risk remained very high, at 36 per cent.

The studies are consistent with other findings that link living conditions -- what they call the social determinants of health – with Type 2 diabetes, as well as other ailments.

Raphael, a professor of health policy and management at York, said conventional wisdom about Type 2 diabetes would suggest that once obesity, lack of physical activity and other lifestyle risk factors were taken into account, diabetes incidence rates would even out between lower- and higher-income groups.

While weight, a sedentary lifestyle and other health problems are still key risk factors, the findings suggest that health-care workers who specialize in diabetes should be paying closer attention to the socio-economic conditions that can lead to them.

"When you're in a situation where 15 per cent of kids and their families are living in poverty, and people are worried from day-to-day about their jobs and homelessness, and immigrants are not being provided with what they need to be healthy, and the evidence that suggests these are all things that contribute to the onset of Type 2 diabetes, there has to be more of a balance in how we understand the causes of illness," Raphael said.

But what is it exactly about living in poverty that contributes to type 2 diabetes?

The studies point to living conditions that put low-income adults and children at risk for myriad diseases, not just diabetes. First of all, there is the chronic stress of low-income living that can adversely affect health. The strain of being short on money and living in inadequate housing, or not having any housing at all, can spike levels of cortisol, a hormone released when the body is under stress. While cortisol helps the body deal with stress, constantly elevated levels can cause a wide range of negative side effects, such as high blood sugar levels or high blood pressure.

Residents of lower-income neighbourhoods also often find it difficult to access fresh, healthy foods and programs that promote physical activity, both of which are key to managing stress, controlling weight and, therefore, preventing disease.

Raphael also points to previous research, which suggests adverse circumstances in early childhood, from low birth weight to deprivation as a youngster, raise a child's risk of developing a number of conditions, from respiratory and cardiovascular diseases to diabetes.

Indeed, a report released this week from The Children's Hospital of Philadelphia found that children who have ever lived in poverty have significantly poorer health outcomes than children who have never experienced poverty, ranging from developmental delays and psychological problems to higher rates of asthma and more frequent hospitalizations.

"So we're basically talking about systematic stress over time, lack of control that eventually leads to higher cortisol levels, among other things. Cortisol and other stuff literally messes up the ability of the body to use the insulin that's available. And it's not well understood," Raphael said.

Poor more likely to suffer complications

For another part of their study, the researchers interviewed 60 diabetes patients who reside in low-income Toronto neighbourhoods. What they learned is that the very conditions that contribute to diabetes also make it extremely difficult to manage the disease, meaning low-income patients are suffering from some of the most debilitating side effects.

Raphael and his team found that insufficient income, inadequate or insecure housing and food insecurity were key barriers to managing the disease. According to their interviews, 72 per cent of patients said they lacked the financial resources to follow the kind of diet needed to keep their diabetes in check.

Many said they had to choose between paying rent or feeding their children and managing their disease.

Michelle Westin, a community health worker with the diabetes education program of the Black Creek Community Health Centre, which services a low-income northwest Toronto neighbourhood, says she sees a number of barriers among her clients to successfully managing their diabetes.

Westin cites language as a barrier of particular concern for recent immigrants, who end up having trouble navigating the health-care system, understanding information or directions from their doctors, and communicating their needs.

Other barriers include:

  • High costs of medical equipment, such as blood-sugar test strips. If patients don't have private health insurance, they are paying for many of these supplies out-of-pocket.
  • Lack of access to healthy foods, and free and safe physical activity programs.
  • Stress and isolation, especially for lower-income seniors, which causes blood-sugar levels to spike.

Westin said experts need to advocate for more affordable food, better access to medications and supplies, and more community services to assist lower-income people prevent and treat diabetes.

Raphael said his team's findings show that tackling broader issues of poverty -- lack of employment or under employment, housing, food security and health coverage -- are key to managing diabetes, and other ailments.

"The primary thing is basically for the government, with other sectors of society, to manage the economy in the service of all," he said.