Dr. Patricia A. Deuster Video (Text Version)
Our research has focused on health disparities in particular among the black or African American population. Black people have disproportionately higher incidents of cardiovascular disease than whites and also other diseases such as hypertension, obesity, and metabolic syndrome.
Our research involved recruiting African Americans or blacks and Caucasians, and we were interested in comparing biologic differences in the stress response and in other characteristics. In particular, we looked at lipid profiles, we looked at behavioral patterns, psychological characteristics, and we conducted a maximal exercise test. But we also were very interested in insulin resistance.
Fasting insulin and insulin resistance are higher among blacks across the life span more than whites. And so we wanted to look at insulin resistance. We administered a standardized meal and we did that actually under two different conditions.
One of our hypotheses was that it-that African Americans are more insulin resistant because they are more sensitive to the stress hormone cortisol or glucocorticoids. So we conducted this standardized meal under two conditions-placebo and dexamethasone which is a glucocorticoid agonist. They would come into the laboratory and they'd complete some questionnaires and then they would have a meal. We would feed them the standardized meal and they would sit in the chair. The meal was actually Ensure, and they drank about 800 calories of the Ensure and then we took blood. We took blood for glucose and insulin every 15 to 30 minutes over a course of about 2 hours. And then they rested for a while after the meal and then they had a maximal exercise treadmill test and we would hook them up and put them on the treadmill and they'd start walking at a slow speed, just to warm them up and then after 5 minutes we'd look at their heart rate. And depending on what their heart rate is, then they start a standardized test where the grade is set at zero and they walk or run at a given speed. And then we increase the grade every 2-point-2.5% every 2 minutes until they can go no further.
We're actually very excited about the conclusions, and I can break it down into three different categories. First, in terms of cardiovascular fitness, the African Americans had much lower cardiovascular fitness than the Caucasian population. In fact, when we classified them, 50% of them were in the low category compared to only about 31% of the white population. And that was a disturbing finding because it suggests that cardiovascular fitness may be contributing to health disparities and particular insulin resistance and cardiovascular disease.
Another finding that we think is very important is their lipid profiles. There are certain cutoffs right now that people use to classify you as being at-risk for cardiovascular disease, and they use triglycerides and high density like with protein cholesterol. And what we found was that there is a huge difference between blacks and whites. In particular, triglycerides tend to be very low in the black population and ours which was in apparently a healthy population because they had been screened for many different diseases and certain characteristics, only 3% of the blacks had a triglyceride value over 150, which is the cut-off, compared to 25% of the white population.
The same difference was noted for the high density or the HDL cholesterol. Now what makes this important is that if we're going to use the 150 milligram per deciliter cut-off for blacks then we're not going to be able to find anyone who is-has-is at-risk for cardiovascular disease because they just traditionally or classically have low values. So we think this is very important clinically.
One of the other interesting findings was at the standardized meal. When we compared the placebo and the dexamethasone, and what we found was that in response to the meal, insulin and glucose were much higher in the black population than in the Caucasian population which tells us that they are hypersensitive to cortisol or to glucocorticoids and that could be a reflection of the stress response.
And glucocorticoids can contribute to insulin resistance so we feel that this is something that could in the future be used as a way to explore either interventions or other mechanisms for developing insulin resistance in blacks-in the black population.
I think that some of the research that CDMRP funds is just-it's just great. Now I happen to be at a military school so I was aware of it, but I know there must be many other investigators who are thrilled to have this kind of funding to be able to do research that can benefit the Military.
As a result of our research, we've already published four papers. They're in peer review literature and we have two more that are in press. And we have several more that are in preparation so I think it's been a good investment for them to fund our project because we've been very productive.