Diabetes will be a bigger burden than first predicted, according to a study released Thursday that examines an increase in the prevalence of the disease.

Using population-based data from Ontario, a Toronto-based research team observed a 69 per cent increase in the prevalence of known diabetes from 1995 to 2005, according to a study by the Institute for Clinical Evaluative Sciences published in The Lancet.

The provincial figures mirror what is believed to be happening in the rest of Canada, experts say

Dr. Lorraine Lipscombe, of Toronto's Women's College Hospital and Dr. Janet Hux, of the Sunnybrook Health Sciences Centre found that the prevalence of diabetes increased from 5.2 per cent in a population of more than 7,900,000 in 1995 to 8.8 per cent of a population of nearly 9,300,000 in 2005.

Although prevalence rates have remained higher in people aged 50 or older than in those aged 20 to 49, rates increased to a greater extent in the younger population.

The study found a 31 per cent increase occurred in yearly incidence over six years, from 6.6 per cent per 1,000 in 1997 to 8.2 per 1,000 in 2003.

The increase in prevalence over the 10-year time frame can be attributed to both rising incidences and declining mortality, the researchers said.

"Effective public-health interventions aimed at diabetes prevention are needed, as well as improved resources to manage the greater number of people living longer with the disease," the report said.

This increase already exceeds the World Health Organization's prediction of a 39 per cent rise in the worldwide prevalence of diabetes.

"Given this linear growth in the prevalence of diabetes, more than 10 per cent of the adult population of Ontario will be diagnosed with diabetes before 2010," Lipscombe, lead author of the ICES study, told The Canadian Press.

"If similar trends are occurring throughout the developed world, then the magnitude of the emerging diabetes epidemic is far greater than we anticipated."

The authors of the study acknowledge the rising rate could be partly to due widespread immigration from South Asia. Ethnic origin is a well-known risk factor for the disease within individuals of African, Caribbean, Latin American and Asian descent all being particularly susceptible.

An editorial that accompanies The Lancet study says these at-risk populations require a tailored approach to prevention and management.

"The increasing incidence observed in ethnic minorities and the young, coupled with decreasing mortality rates and extended life expectancy, means that prevention is the best method of reducing the global burden of diabetes," the editorial says.

"Regular screening programmes must be available for those most at risk, to ensure early diagnosis and effective control."

Doctors need to be aware of cultural influences that affect specific high-risk populations, the editorial urges, such as diet and lifestyle, with an emphasis on self management in the community.

The findings are of concern, the researchers said, because diabetes is one of the leading causes of blindness, an important cause of cardiovascular complications, and the most common cause of end-stage renal disease in developed countries.

Furthermore, they warned that the treatment for diabetes is costly, with direct health-care costs ranging from 2.5 per cent to 15 per cent of health budgets.

The rates of diabetes are only expected to keep rising. The WHO has forecasted that prevalence among adults will reach 6.4 per cent by 2030, which accounts for a 60 per cent increase since 1995, and a 39 per cent rise from 2000 to 2030.

"However, these projections are likely to be underestimates, since they were based on an unwarranted assumption that obesity rates would remain constant," the study says.

One piece of good news the researchers found is that the rate of death dropped by 25 per cent over the decade, Lipscombe said.

The researchers used information from a diabetes registry based on hospital records and physician claims to reach conclusions on diabetes prevalence, incidence and mortality in Ontario from 1995 to 2005.