Prenatal health could be key in preventing diabetes

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A recent study done by researchers at the University of Saskatchewan suggests promoting better nutrition and increased physical activity among pregnant Aboriginal women could help both the women and their babies avoid developing type 2 diabetes.

The study, conducted at the Saskatoon Royal University Hospital between January and July 1998, looked at information from 1,612 women who gave birth at the hospital and who were tested for gestational diabetes, and agreed to participate in the study. Of that total, 252 were Aboriginal, and 1,360 were from the general population.

The overall percentages showed rates of gestational diabetes for the general population was 3.5 per cent, while the rates for Aboriginal women were 11.5 per cent.

The rates of gestational diabetes for women living outside of the Saskatoon Health District were 3.1per cent for women in the general population, and 22.8 per cent for Aboriginal women. The high rate of gestational diabetes for Aboriginal women from outside of the health district can be explained in part by the fact that women from northern Saskatchewan who are sent to the Royal University Hospital to deliver are usually those considered as high risk pregnancies.

When just women living within the health district were considered, the rates were 3.7 per cent for women in the general population, and 6.4 per cent for Aboriginal women.

Dr. Roland Dyck was lead investigator on the study, and is a member of the U of S department of medicine at the Royal University Hospital.

According to Dyck, the study was undertaken to determine whether Aboriginal women have a higher rate of gestational diabetes because they have more risk factors, or whether being Aboriginal was in itself a risk factor.

"And so we did this study, where we directly compared Aboriginal and non-Aboriginal women, and we found that, first of all, Aboriginal women do have higher rates of gestational diabetes, at least twice as high and maybe more. But on top of that, we found that being Aboriginal was in itself an independent risk factor for gestational diabetes. But that depended on the presence of obesity before pregnancy," Dyck explained.

"In other words, if an Aboriginal woman was not overweight when she became pregnant, her risk of developing gestational diabetes wasn't much higher than a non-Aboriginal women. But if an Aboriginal woman was overweight before pregnancy, then her risks of developing gestational diabetes were five or six times higher than a non-Aboriginal woman who was also obese. So there's some kind of interaction between being Aboriginal and being overweight before pregnancy that puts a very high risk of gestational diabetes on that woman. And then in turn, we think that puts a risk on the baby of developing diabetes when he or she becomes an adult."

Gestational diabetes doesn't only increase the baby's chances of developing type 2 diabetes later in life, Dyck explained. It also affects the mother's chances.

"Certainly women who've had gestational diabetes are much more likely to develop type 2 diabetes later in life. And some work among Aboriginal women, I think particularly from the Sioux Lookout area of northern Ontario, I think they've shown something like 70 or 80 per cent of women who've had gestational diabetes will end up with diabetes. Now, we're not sure whether its just that gestational diabetes is a marker for somebody who's going to get type 2 diabetes later in any case, or whether there's something about pregnancy and gestational diabetes that actually increases the risk for that woman to get type 2 diabetes. I think it's probably a bit of both," Dyck said.

One theory for the increased rate of gestational diabetes among Aboriginal women that Dyck and the other members of the research team have come up with through their research is the hefty-fetal type hypothesis.

"This is pure speculation, but we wonder whether, back thousands of years ago . . . it may have been to their surviva advantage for women in the child bearing age group to be able to conserve calories so that when they got pregnant, they would be nutritionally in good shape, and that would make it more likely that their babies would be healthy. But if you take that same population into modern times, when nutrition is often over-abundant, and often is not very high quality in disadvantaged groups, then that pre-disposes us to obesity, and we know that can cause type 2 diabetes. But in young women, we think that also is what predisposes these women to gestational diabetes. And there's something about the intrauterine environment in women who have gestational diabetes that has an affect on the fetus, so that fetus also gets more nutrition than it really needs, and is more likely to be born big and also to have this risk of developing diabetes in his or her self later on," he said.

"We really think that gestational diabetes is a key in the whole diabetes epidemic," Dyck said, suggesting that, if that is the case, then it would make sense to focus efforts on promoting better nutrition and increased physical activity- something that research has shown does lessen the chances of developing gestational diabetes-among young Aboriginal women.

"I think it might be easier to encourage women to go into pregnancy at a healthy weight, or to have them exercise and eat well during pregnancy, because most women are well motivated when they're pregnant, for their unborn child. And it's a relatively short period of time compared to a lifetime," Dyck said.

"And so I think it's maybe an ideal time to really focus on prevention aspects, and if we could prevent gestational diabetes, we might be able to have some impact in the longer term on the rates of diabetes that we're observing in Aboriginal people."