University of Saskatchewan

September 16, 2014   

Overweight Aboriginal Women at Dramatically Higher Risk for Gestational Diabetes

July 03, 2002

University of Saskatchewan researchers have found that overweight Aboriginal women are almost five times more likely to develop gestational diabetes (GD) than overweight non-Aboriginal women.

In a recently published study, Aboriginal women were also found to have twice the risk of GD compared with women in the general population after adjustment for other potential variables. Many pregnant Aboriginal women with GD, as well as children of GD pregnancies, later develop Type 2 diabetes, a current epidemic in Aboriginal communities.

"This is the first time in Canada that Aboriginal women with and without GD were directly compared to non-Aboriginal women," said Dr. Roland Dyck, lead investigator on the study and a member of the U of S department of medicine at Royal University Hospital (RUH).

"We have found that Aboriginal ethnicity is an independent risk factor for GD, and GD could be a key factor in the Type 2 diabetes epidemic because of its impact on the next generation."

While obesity alone does not account for the difference in GD risk, the combination of Aboriginal ethnicity and obesity resulted in dramatically higher levels of GD among Aboriginal women.

The team's research shows that almost 30 percent of Aboriginal women who are obese before pregnancy develop GD, while fewer than five per cent of overweight non-Aboriginal women develop GD. In contrast, the team found that fewer than five per cent of Aboriginal women who are at a healthy weight before pregnancy develop GD, compared to three per cent of non-Aboriginal women.

GD develops during pregnancy when the placenta produces hormones that can cause insulin resistance. This raises blood-sugar levels in both the mother and fetus, and in infants, can cause high birth weight, difficult deliveries, jaundice, and respiratory distress. These infants are also more likely to develop diabetes as adults.

Dyck's team concludes that fitness and nutrition programs are urgently needed for expectant Aboriginal mothers. He thinks exercise could significantly reduce both GD and Type 2 diabetes. Regular physical activity reduces insulin resistance and blood sugar levels, increases energy, and helps to control weight gain. Increased fitness also contributes to easier pregnancies and deliveries.

The study involved more than 2000 Saskatchewan women, of whom 252 were Aboriginal. Findings were published in Diabetes Care, an American Diabetes Association healthcare professional magazine.

Aboriginal obesity may be caused by a "thrifty genotype" -- a survival mechanism that prepares for nutritional hardship by conserving calories when food is abundant. This genotype may have contributed to healthier pregnancies and births centuries ago. But now, when combined with high food intake and decreased physical activity, it's a liability that leads to increased rates of GD and Type 2 diabetes, says Dyck.

"This disease didn't exist in Aboriginal populations 60 years ago," he says, referring to a 1937 Saskatchewan study conducted by Dr. Lillian Chase that didn't turn up a single case of diabetes in a population of Registered Indians. "Theoretically, there's no reason why the current epidemic can't be turned around in another 60 years."

"As exposure to non-Aboriginal lifestyles increases, rates of obesity also increase," said Dyck. "Genetics don't change in 50 years, or even over a century. Lifestyles change."

The study was funded by U of S and Saskatoon District Health. Other U of S researchers included epidemiologist Helena Klomp (medicine), and professors Leonard Tan (community health and epidemiology), Roger Turnell (obstetrics and gynecology), and Makram Boctor (medicine).

For more information, contact:

Dr. Roland Dyck
U of S Department of Medicine
Royal University Hospital
(306) 966-7947

Kathryn Warden
U of S Research Communications Officer
University of Saskatchewan
(306) 966-2506

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