What causes Type 2 diabetes? For most, the answer seems clear: obesity is the top risk factor. But Cal Poly kinesiology professor Marilyn Tseng thinks there may be something else that plays a crucial role.
Before she started teaching at Cal Poly, Tseng worked at the Fox Chase Cancer Center, a research hospital in Philadelphia. Tseng worked with Chinese immigrants for years and she started to see a troubling trend: diseases and conditions that weren’t prevalent for Chinese-Americans suddenly spiked for them once they immigrated.
Diabetes was one of them.
“Even though the Chinese-Americans are thinner than the non-Hispanic white population in the U.S., we’re actually at higher risk for diabetes,” Tseng said. “Usually, the risk factor that we say for diabetes is obesity, but the Asian population is really not obese.”
Initially, Tseng had looked to nutritional epidemiology, or how our nutrition impacts our health, to explain the diabetes phenomenon. It seemed simple: adopting a new culture could mean less healthy eating and more receipts from Buffalo Wild Wings. But Tseng says that’s not the case. Instead, the diets of most Chinese-American immigrants hardly change.
Nutrition was simply not enough to explain what was going on.
At the Fox Chase Cancer Center, Tseng was working with a colleague, a health psychologist named Carolyn Fang. Fang studies some of the psychological factors that can interact with physical health and put people at higher risk for disease. The question bubbled and bubbled until the summer of 2015, when Fang and Tseng received a grant to test a pet theory of theirs, that stress can be the gateway to diabetes.
“There is quite a bit of research over the past three decades which suggests that under conditions of chronic stress, there are certain physiologic changes that occur in the body that might make one more vulnerable to disease,” Fang said.
Much of the research has focused on inflammation, which scientists say can predispose people to develop a metabolic disorder, or a cluster of conditions that eventually materialize into a chronic disease like diabetes.
Stress can be difficult to quantify, but Fang and Tseng are finding a way. The two are working with Clemens Kirschbaum, a researcher from Germany who measures levels of the stress hormone cortisol in hair. Doing this allows researchers to see the stress levels of a person up to six months back, a more long-term look at stress.
The other component is a detailed questionnaire asking the immigrants about their experiences with discrimination, the difficulties of assimilation and the overall emotional experience of their transition.
But studying the effects of stress on physical health can also tread into controversial water.
“We don’t want people to think they’re being blamed for their disease,” Fang said.
Fortunately, epigenetics can provide some support. Epigenetics examines the environment’s influence on our genes, or specifically, the mechanisms by which some genes turn on, and some genes turn off. Knowing this can help develop understanding disease.
If our DNA was once thought to be paramount in uncovering long-term truths about our physiology, epigenetics combs apart the script.
Cal Poly biological sciences professor Sandi Clement will be collaborating with Tseng and Fang on their research to analyze, through epigenetics, how exactly stress “gets into the body.”
Clement’s reasons for wanting to participate in the research aren’t just science for science’s sake. Shortly after she began teaching at Cal Poly, she met Jane Lehr, the department head for Women and Gender Studies, and was inspired by the connections Lehr was drawing between the often inaudible effects of culture on human biology.
Oppression as a physical manifestation was what drew Clement to the research.
“There is some boundary making between scientists looking at epigenetics from a social justice lens, and those looking at it strictly molecularly,” Clement says. “Some of the molecular folks are positioning themselves above and distinct from the folks who are talking about epigenetics through a social justice lens, as a mechanism by which oppression gets into the body physically.”
Tseng, who is a second-generation Chinese immigrant, has a family history of diabetes.
“My family went through a lot of changes to come here, so that’s something that’s always motivated my research,” Tseng said. “I think that’s why I zeroed in so quickly on immigrant health.”
In the late ‘60s, women rallied to link the personal and the political. Tseng, Fang and Clement, albeit with microscopes, are doing it again.
“I discovered there’s a whole bunch of biologists out there, professional biologists, who found a way to align their work with their values,” Clement said. “It never occurred to me that you could do that. I thought maybe you weren’t supposed to, because that would make the science less objective.”
Tseng says the connection between stress and diabetes is a new idea doctors are just now coming to terms with. Most do not tend to check Chinese-Americans for diabetes, which is a problem. If Tseng and her colleagues can confirm what they hypothesize, it doesn’t just benefit the Chinese-American community, but any other population that may be getting overlooked.
The grant Fang wrote will last five years. So far, they’re about halfway done collecting data, which means the project is still a bit of a mystery. Tseng likens it to a black box.
“Stress goes into the box, something happens, and you get an illness,” Tseng said. “We want to know, what happens in that box?”