NEW YORK (Reuters) -– Type 2 diabetes is much more common among Canada's native people than their non-native counterparts, and women of childbearing age are particularly at risk, new research shows.

What's more, there's a “striking difference” in the age at which the two groups develop the disease, Dr. Ronald Dyck of the University of Saskatchewan in Saskatoon and his colleagues found. New cases peaked among native individuals -- who are known in Canada as First Nations people -- when they were in their 40s, while Canada's non-indigenous adults typically develop type 2 diabetes at age 70 or later.
The findings suggest, Dyck and his team say, that there may be “fundamental differences” in how and why First Nations and non-First Nations individuals develop type 2 diabetes. But the reasons behind this difference are still unclear.
In Saskatchewan in 1937, not a single case of diabetes was detected among 1,500 First Nations people who participated in a tuberculosis survey, Dyck and his team note in the Canadian Medical Association Journal. By 1990, nearly 10 percent of the province's native people had diabetes; by 2006, the proportion was over 20 percent.
To better understand this “evolving epidemic,” the researchers looked at over 8,000 First Nations adults and about 82,000 non-First Nations adults living in Saskatchewan who developed type 2 diabetes between 1980 and 2005.
The rise in diabetes prevalence over that time was similar among all study participants, roughly doubling among women and tripling among men. But while type 2 diabetes was equally common among non-native men and women in 1980, with about 2 percent of both groups having the disease, the 1980 prevalence of diabetes for First Nations adults was nearly 10 percent for women and 5 percent for men. By 2005, 20 percent of First Nations women and 16 percent of First Nations men had type 2 diabetes, compared to around 6 percent of non-First Nations men and women.
In 2005, the researchers found, nearly half of First Nations women 60 and older had type 2 diabetes and over 40 percent of men 60 and older did, compared to less than 25 percent of non-First Nations men and fewer than 20 percent of women in this age group.
Given that the gender difference in diabetes rates among First Nations adults was due to a particularly high rate of the disease among women 20 to 49 years old, Dyck and his colleagues say, gestational (pregnancy-related) diabetes could be a contributing factor.
While it's not clear how much of the increased rate of diabetes among indigenous Canadians is due to genes or environment, they add, “what is clear is that the rapid appearance of type 2 diabetes among First Nations people and other indigenous and developing populations has been precipitated by environmental rather than genetic factors.”
It's worth noting, the researchers say, that rates of type 2 diabetes are also higher among the United States' indigenous population.
Prevalence among Native Americans varies widely from region to region, but overall around 17 percent of Native American adults have type 2 diabetes, compared to around 7 percent of non-Hispanic whites and Asian Americans and around 12 percent of Mexican-Americans and Puerto Ricans, according to 2007 statistics from the National Institute of Diabetes and Digestive and Kidney Diseases.