A Step in the Right Direction
Walking improves cardiovascular health of patients with diabetic kidney disease
By Nancy Giguere
Some 24 million Americans—about 8 percent of the population—have diabetes. Over 90 percent of these have type-2 diabetes, which is caused by the inability of fat, liver, and muscle cells to respond normally to insulin. As a result, sugar cannot enter the cells. Instead it builds up in the blood and damages blood vessels and organs throughout the body.
Kidney disease is of one the most common complications of type-2 diabetes. Individuals with diabetic associated kidney disease are also at increased risk for cardiovascular disease. In fact, the incidence of cardiovascular disease in these patients is 15 to 20 times higher than it is in those without diabetic kidney disease.
An interprofessional team
Although diabetic associated kidney disease cannot be cured, it can be managed through medication and lifestyle changes. One of most important elements of healthy lifestyle is exercise, and that’s the focus of research study led by Ulf Bronas, PhD, ATC, ATR, a clinical assistant professor and exercise physiologist in the
School of Nursing.
Bronas specializes in exercise interventions to prevent and manage chronic disease. With funding from the National Institutes of Health, he and his team of researchers are investigating the effects of supervised exercise training on cardiovascular and physical health in people with diabetic associated kidney disease.
The interprofessional team includes Patricia Painter, PhD; Diane Treat-Jacobson, PhD, RN, FAAN; and senior statistician Kay Savik, MS from the School of Nursing. Also participating are Marc Weber, MD; Mark Rosenberg, MD; Connie Manske, MD; and Daniel Duprez, MD, PhD, from the Medical School, and Robert Hebbel, MD, of the vascular biology lab at the Masonic Cancer Center.
Assisting the researchers are undergraduate and graduate students from the School of Nursing. For these students, the study offers not only a chance to participate in research, but also an opportunity to develop their interpersonal skills as they interact with patients.
Signs of disease
“Study participants are usually sedentary and show evidence of inflammation caused by oxidative stress,” Bronas explains. In other words, their cells are being damaged by a process which resembles the changes that occur when an iron pipe begins to rust after years of exposure to the elements.
Oxidative stress leads to dysfunction of the endothelium, a layer of cells that lines the heart, blood, and lymph vessels. These cells play a critical role in regulating vascular health and tone, blood flow, and artery remodeling and repair. Dysfunction of the endothelium is associated with cardiovascular disease.
Study participants range in age from 40 to 83, with an average age of 67. They meet with Bronas for 60 minutes once a week for 12 weeks. The first session includes a walking exercise on a treadmill to determine the individual’s current exercise capacity, along with blood tests and ultrasounds of the major arteries, which are used to examine the condition of the endothelium.
For patients, regular exercise is often life-changing.
An individual prescription
Bronas creates a prescription for each patient based on individual exercise capacity and health status. This is programmed into a monitor that patients wear while exercising on their own.
“They learn how to exercise in the lab, and then we give them homework to do,” Bronas says. Participants are asked to walk four or five times during the week. The monitor records their heart rate, the length of time they exercise, and the number of calories they burn. The monitor also keeps participants on track: a beeper warns them to slow down if they’re working too hard or to speed up if they begin to slack off.
Each week when patients return to the lab, Bronas downloads the information recorded in the monitor, analyzes it, and adjusts the exercise intensity and duration, as well as the target heart rate.
At the end of 12 weeks, participants are once again evaluated on the treadmill, their major arteries are reimaged, and their blood is retested.
Dr. Ulf Bronas and Pamela Baker (lab technician) with study participant Marty Harris, in the vascular biology lab at the Masonic Cancer Center. Using ultrasound, Bronas and Baker examine the condition of Mr Harris’ arteries.
Preliminary findings from the study are encouraging. For individual patients, the results are often dramatic and life-changing.
For example, one man could barely walk for five minutes on the treadmill at the beginning of the study. His blood pressure was high and his blood glucose was poorly controlled. He was tired and had trouble catching his breath. Twelve weeks later, his blood pressure and glucose levels were lower, he had lost some weight, he was breathing more easily, his energy level was higher, and he could walk for more than 30 minutes. Marty Harris experienced similar results eight weeks into the study. “I was never one for exercise,” he says. “But now I walk six days a week. I feel so much better, my legs are stronger, and I have more energy all day long.”
If the study is successful, it could translate into new therapies that will reduce morbidity and mortality rates for patients with diabetic kidney disease. “The result would be more cost-effective health care and a better quality of life for millions of people,” Bronas says.
Click here to learn more about how Dr. Bronas is exploring lifestyle interventions to help patients with type II diabetes avoid cardiovascular disease.
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Ulf Bronas, PhD, ATC, ATR