Soaring Diabetes Rates Over Past 10 Years in Ontario Far Exceed WHO Projections

Shelley Wood

March 02, 2007

March 2, 2007 (Toronto, ON) - In the past 10 years, the prevalence of diabetes in the province of Ontario, Canada, has already exceeded the global rate projected by the World Health Organization (WHO) for 2030, researchers report in the March 3, 2007 issue of the Lancet [1]. The WHO report had predicted a 39% increase in the rate of diabetes in the first 30 years of the 21st century [2], Drs Lorraine Lipscombe and Janet E Hux (Institute for Clinical Evaluative Sciences, Toronto, ON) note in their paper.

"We have available to us Ontario population-based data on newly diagnosed diabetes, and we've been tracking rates of diabetes for the past 10 years," Lipscombe told heartwire . "We found that between 1995 and 2005 the rate of people affected has gone up by almost 70%, which is far greater than what was predicted by the WHO."

According to Lipscombe and Hux, the age- and sex-adjusted diabetes prevalence in Ontario increased from 5.2% among 7 908 562 Ontario citizens in 1995 to 8.8% of 9 276 945 in 2005. Diabetes prevalence increased by one third during the first five years and by an additional quarter during the second five years. At the same time, the adjusted mortality rate for diabetics has fallen by 25% over the 10-year period studied. Importantly, however, while diabetes rates have been higher in older men and women (50 or older), the rate of increase has been steeper in younger Ontarians, aged 20 to 49 years.

"What we were able to determine in our paper is that the increase in overall prevalence of diabetes was due to both an increase in new cases over at least a six-year window and a decline in mortality among people with diabetes, so people are living longer with the disease," Lipscombe commented. "Both of those factors are contributing to the increased population of people with diabetes."

The WHO projections, published in 2004, acknowledge that the predictions are conservative, based on the assumption that obesity rates would remain constant.

"We know now that hasn't been the case," Lipscombe observed. "So that may be why we're seeing a much larger increase than predicted."

She does not think healthcare workers will be surprised by the numbers. "Even in my short career, I've been seeing large increases in people with diabetes," she said. She also added that Ontario is "fairly representative" of the rest of Canada and other developed countries, with a mix of urban and rural populations and a multicultural society.

Ethnicity may be important

Where Ontario may differ slightly from other regions may be in the ethnic makeup of its immigrant population. "Although we did not look at the impact of ethnicity in the paper, we do know that Ontario has seen a large increase in immigration of at-risk populations such as people of South Asian origin," Lipscombe stated. "So it's possible that that has also contributed to the increased rate, in that our mix has changed over the past 10 years and we're seeing more susceptible populations within our province."

If there is a bright side to the gloomy statistics, it's that diabetes mortality has declined in Ontario over the past decade. "This suggests physicians are doing a much better job of taking care of patients with diabetes," she said. "I think that over the past 10 years we've seen a lot of progress in preventing complications such as CVD. So it's a good-news story for physicians; however, for those who haveto counsel people on diabetes risk, this alerts physicians to the fact that they need to be much more aware that the risk is very real and that they should take every opportunity to advise people on diabetes prevention."

A Lancet editorial points out that the Ontario data highlight the need for regular screening programs and for doctors to be aware of cultural influences that affect different populations at higher risk for developing diabetes [3]. "A one-size-fits-all approach is not optimal for the treatment of a disease that affects subpopulations differently," the editorial observes. "Every country needs to devise a customized policy of care, dependent on the ethnic constitution of its population, for effective worldwide control of diabetes to be attained."

  1. Lipscombe L, Hux JE. Trends in diabetes prevalence, incidence, and mortality in Ontario, Canada 1995-2005: a population-based study. Lancet 2007; 369:750-756.

  2. Gregg EW, Cadwell BL, Cheng YJ, et al. Trends in the prevalence and ratio of diagnosed to undiagnosed diabetes according to obesity levels in the US. Diabetes Care 2004; 27:806-812.

  3. [No author listed]. Targeting high-risk populations in the fight against diabetes [editorial]. Lancet 2007; 369:716.

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