Research Shorts May 2008
The Research Shorts section features articles about cutting-edge research relating to diabetes. The studies presented in this section involve products, technologies, and theories that are in the early stages of testing and development. Because there's no way to know which studies will pass the test of time, it's important that readers not base any treatment decisions on these results.
Diet Soda Fizzes
You may want to put down that diet soda. New research inserts a question mark after the "diet" part of your drink.
In the study, people who drank a can or more of diet soda daily showed a 34-percent higher risk of developing the metabolic syndrome: a cluster of cardiovascular disease and diabetes risk factors including elevated waist circumference and high blood pressure, blood lipids, and fasting glucose levels.
Why would that be? Study coauthor Lyn Steffen, PhD, MPH, RD, says she is as mystified as the rest of us. But she offers some possible explanations. "It could be an ingredient in the soda itself, like the artificial sweetener, which might be causing something like insulin resistance," speculates Steffen, associate professor of epidemiology at the University of Minnesota. "Or it could be something to do with the behavior of people who consume diet soda—what other foods they're eating and how much exercise they're getting throughout the day."
Her research team tracked the dietary intake and health status of 9,500 men and women, 45 to 64 years old, over nine years. They found that people who ate the most meat raised their risk of developing metabolic syndrome by about 25 percent. And those who regularly ate Western-style cuisine like refined grains and fried foods upped their risk 18 percent.
But diet soda involved the highest risk—and, Steffen notes, a recent Purdue University study suggests a possible reason. In that study, rats eating saccharin-sweetened yogurt consumed more of it, and gained more weight, than rats eating sugar-sweetened yogurt.
In Steffen's study, most diet sodas "were likely sweetened with aspartame, not saccharin, but it could be the two work similarly," she says. "So maybe diet soda consumers are eating more." This isn't the first study to link the metabolic syndrome and diet soda. However, past studies show the link with sweetened soda as well as diet versions. This study showed no such association between sweetened beverages and the syndrome.
But that's no reason to start drinking sugary sodas, which are loaded with empty carbohydrates. Instead of reaching for soda (regular or diet), Steffen suggests trying water or green or black tea. Another good bet is skim milk. Steffen's team found that low-fat dairy products help stave off the metabolic syndrome.
The American Heart Association published the diet soda findings online on Jan. 22, 2008, in its journal Circulation. The saccharin and weight-gain study appeared in the Feb. 2008 issue of the journal Behavioral Neuroscience.
Bridget Murray Law
Foot Ulcer Hot Spots
Worried about ulcer problems? It may be time to take your foot temperature.
As many as a quarter of people with diabetes develop foot ulcers, which can escalate into gangrene, bone infection, and possibly even lower limb amputation. But a simple surveillance tool—a foot thermometer—can help prevent these dangerous sores, according to recent research.
Ulcers form when diabetic neuropathy numbs the extremities to pain. Without being able to feel that sting, a person can be oblivious to a developing ulcer. However, there's another way to predict whether an ulcer is about to bloom, says David Armstrong, DPM, MSc, PhD, professor of surgery at the Rosalind Franklin University of Medicine and Science in Chicago: a rise in skin temperature.
Armstrong and his team found that patients who measured foot temperatures were only a third as likely to develop ulcers, compared with those without thermometers. Their findings were reported in the Dec. 2007 issue of The American Journal of Medicine.
The study enrolled 225 veterans with diabetes who were at high risk for foot ulcerations. All were educated about foot care and ulcer signs, but half were also issued special thermometers designed for taking surface skin temperatures. Twice a day, participants tested six positions on each foot, and recorded the readings in a journal. The researchers advised them that foot-skin temperature should only vary a half degree between sites; any temperature differences greater than four degrees indicate inflammation—a tell-tale sign that an ulcer is brewing.
They told anyone who registered such high readings to contact the study nurse and rest until the temperature equalized. Some didn't heed this advice, and developed ulcers. These participants recorded foot temperatures five degrees greater than normal at the site where ulceration would occur for up to a week before the skin actually broke.
By the end of the 18-month study, five thermometer-users developed ulcers, compared with 14 of the other veterans. The study does not say, however, whether the lower ulceration resulted from the temperature readings themselves or the increased attention paid to feet during thermometer use.
"It seems like, for whatever reason, this draws people into their own care," says Armstrong. "It's so simple and inexpensive, it's exciting."
The medical thermometers used in the study cost $150 each, although Armstrong predicts the price will drop. In addition, the company that supplied the thermometers is developing a foot thermometer that one steps on like a bathroom scale.
Erika Gebel, PhD
A Potential Tool to Warn of Type 1's Attack
In a small but ground-breaking study, researchers have discovered a genetic fingerprint for type 1 diabetes—a sort of early warning marker that emerges years before diagnosis. Depending on the results of future studies, this fingerprint could serve as a diagnostic tool that allows for prevention of the disease.
Generally, type 1 is predicted—primarily in research studies—when blood tests identify the antibodies that wage war against the insulin-producing beta cells of the pancreas. The use of antibodies as a predictive tool has drawbacks, however. Preventing full-blown type 1 should ideally happen before or during the immune attack, while there are still beta cells left to save. But since antibodies never fully recede and are sometimes found in the absence of type 1, they don't give good information about when or in whom to initiate potentially risky experimental preventive therapies—like insulin or immunosuppressive agents—or about whether the therapies are working.
The advantage of this new genetic signature is that it seems to appear only while beta cells are being actively targeted by the immune system. "One day we will be able to find the kids with beta cells being destroyed and keep these kids from becoming diabetic," says the study's principal investigator Martin Hessner, PhD, associate professor at the Medical College of Wisconsin in Milwaukee. "That's the dream."
For the study, researchers used blood samples from 12 people with recent-onset type 1, 12 people with long-standing type 1, 12 nondiabetic controls, and nine "at-risk" siblings of people with type 1. The researchers incubated the samples with healthy cells. After six hours, proteins in the blood from the recent-onset group entered the healthy cells and activated the type 1 genetic pattern, but the blood proteins of the control and long-standing type 1 group did not. Since the signature was able to differentiate between recent-onset and long-standing diabetes patients, the researchers concluded it may be a hallmark of an active immune attack.
The findings on the at-risk siblings were especially provocative: Three presented the signature up to five years before being diagnosed with type 1—one of them before the antibodies showed up. Meanwhile, two other siblings possess the signature, but as yet have not developed diabetes. "If the approach is predictive, [these two] would be the two that develop type 1," says Hessner. Interestingly, the remaining four at-risk siblings have the antibodies, but neither the signature nor diabetes. "They had some immune activation," he says, "but it's been turned off."
The results are promising but far from conclusive, says Hessner. "We've got a long way to go, but there's reason to be optimistic." The study was published in the Feb. 1, 2008, issue of the Journal of Immunology.
Why Heart Rates May Matter
A higher resting heart rate in adulthood means a higher risk of diabetes—and diabetes-related death—after age 65, finds a study by researchers at the Feinberg School of Medicine at Northwestern University.
The finding is consistent with previous studies, but according to researchers it comes from the longest ever follow- up study investigating heart rate and diabetes.
Researchers used data from the Chicago Heart Association Detection Project (1967 to 1973), which measured the resting heart rate of nearly 15,000 men and women ages 35 to 64. Thirty-five years later, the Northwestern researchers followed up to determine the rate of development of diabetes as well as the incidence of diabetes-related deaths in that group. They checked participants' Medicare billing records to determine who had filed diabetes-related hospital claims, indicating that they'd developed diabetes. Though records did not distinguish between type 1 and type 2, the age of the participants evaluated at follow-up (older than 65 years) indicates that most cases of diabetes were type 2.
After accounting for demographics, smoking, and other factors, the odds of having a diabetes-related claim were 10 percent higher for every 12 beats per minute higher a person's heart rate had been 35 years earlier.
The researchers were not surprised by the findings because a higher heart rate indicates reduced fitness of the cardiac, respiratory, and nervous systems—and a possibly increased risk of diabetes. In particular, a chronically high heart rate can compromise nerve fibers that help secrete and release insulin, the researchers explain.
"Resting heart rate is a measure of both autonomic nervous system function and fitness, both of which we know are related to the development of diabetes," says Mercedes Carnethon, PhD, lead author of the research. And what people do affects that measure, she emphasizes, adding that "regular physical activity … may be an effective means to prevent diabetes."
The study was published in the February 2008 issue of Diabetes Care.