There has been a dramatic increase in the number of Chinese Canadians diagnosed with type 2 diabetes, a new study has revealed.
The researchers are surprised by their findings because Canadians of Chinese ethnicity have not been considered especially prone to the disease.
"We need to find a way to slow this down," said the study's senior author, Dr. Baiju Shah, a scientist at the Institute of Clinical Evaluative Sciences in Toronto. He suspects that changes in lifestyle – ranging from diet to physical inactivity – are likely behind the disturbing trend.
The study indicates the incidence of diabetes jumped 15-fold between 1996 and 2010 among Canadians with Chinese origins, while it increased only 24 per cent in those with a European background.
The results, published Thursday in the journal Diabetes Care, are based on an analysis of two sets of data. One set included a series of health surveys carried out by Statistics Canada between 1996 and 2005. Information gathered from people who identified themselves as either of Chinese or European descent living in Ontario was then matched to that province's health-care billings, which allowed the researchers to chart new diabetes cases over five years of follow-up. In total, the researchers tracked 77,000 people who were free of diabetes at the start of the study, taking note of those who were eventually diagnosed with the disease.
The results revealed that in 1996 there were 1.3 newly diagnosed cases of type 2 diabetes per year for every 1,000 individuals of Chinese background in Ontario. By the end of the study period in 2010, the annual incident rate of newly diagnosed cases shot up to 19.6 per year for every 1,000 Chinese-Canadian individuals.
By contrast, the increase in cases was substantially lower among people of European ethnicity. It went from 7.8 new cases per year per 1,000 people in 1996 to 9.7 per year at the conclusion of the study.
"We are not really sure why we have seen such a massive increase over a fairly short period of time," said Shah, who is also an endocrinologist at Sunnybrook Health Sciences Centre in Toronto. But he speculated that it is likely lifestyle-related.
"Over time, this population may have been adopting more unhealthy lifestyles such as eating more energy-dense foods, more processed foods, more fast foods, and moved away from the traditional diet that the older generation of Chinese Canadians ate," he said.
"We've also seen Chinese communities shift from urban-core Chinatowns to suburban regions. So they are moving away from urban, walkable neighbourhoods to more car-requiring, sprawling suburban areas."
A less healthy diet and a reduction in physical activity could contribute to weight gain, which increases the risk of developing diabetes. But weight alone can't fully explain the dramatic increase in diabetes.
"In 1996, the proportion of the Chinese population that was either overweight or obese was 19.9 per cent and it was 25 per cent [at the end of the study]. To put that into perspective, overweight and obesity rate in the European population was 50 per cent to start with [in 1996] and went up to 56 per cent," he said.
"So you can't just blame obesity because there is a lot more obesity in the European population." Indeed, if obesity were the only culprit then Europeans would still be far ahead of Chinese in terms of new cases.
Whatever the underlying cause, the main conclusion of the study is unequivocal: Chinese Canadians should be considered an at-risk group.
"In the past, we have identified other groups at high risk of getting diabetes, such as people from India and South Asia and the First Nations of Canada. The Chinese haven't historically been on that list. But our study indicates they now should be."
The overall percentage of the population with diabetes is roughly the same among people of Chinese and European origins. (Slightly more than 4 per cent of each group is living with a diagnosis of diabetes.)
"Our data show that now the number of new cases of diabetes is doubled for Chinese compared to European Canadians." He expects the percentage of Chinese Canadians with diabetes will soo
Dr. Alice Cheng, an endocrinologist at St. Michael's Hospital in Toronto, noted that many of her patients are of Chinese descent. She says doctors should be considering ways to reduce the risk of diabetes among their Chinese patients. "A big part of that strategy is lifestyle modifications and that includes regular physical activity, healthy eating and maintenance of a healthy body weight." In some cases, she added, patients may benefit from certain medications to keep diabetes at bay.