Noninvasive approach to diabetes screening and monitoring shows promise
Diabetes is epidemic in this country, and healthcare professionals understand that early diagnosis and treatment offer the best hope for preventing the costs and debilitating complications associated with the disease. And yet only about one in five Americans at high risk for developing diabetes is screened for the disease each year.
Part of the problem is that the most commonly used screening method, fasting plasma glucose (FPG), requires an overnight fast and an invasive venous blood draw. And data suggest that it misses roughly half of all undiagnosed diabetics. Consequently, even though providers are well aware that huge numbers of diabetics remain undiagnosed, inconvenient and imperfect screening methods continue to stand in the way of improved care.
However there may soon be an alternative screening method available that is both noninvasive and highly sensitive. Early data suggest that a device made by Albuquerque, NM–based VeraLight, Inc., is able to outperform both the FPG and HbA1c tests in terms of accurately identifying diabetic patients. Additionally, there are indications that the test is also sensitive enough to pick up patients with prediabetes. More extensive clinical studies are planned, and the device—called Scout ™—has yet to be FDA approved, but it is generating interest among clinicians and researchers who are keenly aware of the limitations presented by conventional testing procedures.
Scout offers a wealth of information
The Scout instrument employs fluorescence spectroscopy to measure advanced glycation endproducts (AGE) in the dermis of a person’s forearm. This provides a wealth of information, because the concentration of AGEs in the skin is an indicator of cumulative hyperglycemic exposure and is, therefore, highly correlated with the development of diabetes complications.
“When you are looking at how skin reacts to light, the light as a function of wavelength can be absorbed, scattered, or generate fluorescence in the skin,” explains John Maynard, VeraLight’s vice president of product development. “That wavelength dependence—the amount of light that is returned—actually contains information that is useful in discerning the different chemicals in the skin, so we use the chemical information that is encoded in the light that we detect to then tell whether someone is at risk of prediabetes or diabetes.”
The test is simple to perform, requiring less than a minute to carry out. To undergo testing, a person places the palm side of his or her forearm onto the device, which then shines various wavelengths of light onto the skin. This causes the AGEs to emit a fluorescent light signature, indicating diabetic risk. Clinicians can then immediately interpret the result that is indicated by a number that appears on the device’s screen, which can also be printed out.
“We have, essentially, a baseline for a person at normal health at a given age. And we look at the measurement of a particular individual to see whether it is consistent with the normal population or is progressing away from that line of normalcy toward prediabetes or diabetes,” Maynard says.
Research presented at the World Diabetes Congress of the International Diabetes Federation in Capetown, South Africa, in December 2006, showed that a prototype Scout system device outperformed both FPG testing and HbA1c testing in head-to-head evaluations of 351 people at risk for diabetes or prediabetes. Investigators report that the Scout system was able to identify 30% more people than FPG testing and 17% more people than HbA1c testing. “What we used as our determination of truth was the two-hour oral glucose tolerance test,” says Maynard. “We were able to show that our test agreed much more [than the other testing procedures] with the oral glucose tolerance test, which is the gold standard for diabetes screening and diagnosis.”
VeraLight is now gearing up for a much larger clinical study so that it can collect data to submit to the FDA for approval of the device. The company anticipates being able to present findings to the FDA in late 2007, and with the FDA’s approval, to be able to make the Scout system available to the marketplace by 2008.
Initially, the company envisions the screening device being used to screen people according to guidelines established by the American Diabetes Association. By those criteria, most of the people referred for screening would be age 45 or older and have one or more of the following risk factors for the disease:
For women, the list of risk factors also includes a history of gestational diabetes or polycystic ovary syndrome, or having a baby that weighs more than nine lbs. “The main reason you would use [the Scout system’s] test is because it is more sensitive,” says Maynard. “You are more likely to pick up someone in the early stages of the disease.”
In addition to annual screening for people with risk factors for diabetes, Maynard suggests that the Scout system also has an early application for long-term diabetes monitoring. By tracking AGE accumulation, clinicians could make better decisions about risk stratification and therapy adjustments.
Reimbursement will take time
Infrared or fluorescent-based technologies have a somewhat patchy record in the diabetes field, according to Bruce Buckingham, MD, a pediatric endocrinologist and associate professor at Stanford University in Palo Alto, CA. However, he is intrigued by the Scout system, and believes that it could offer valuable information to both researchers and clinicians. “One blood sugar doesn’t tell you much, and an HbA1c test gives you several months of data, but it often takes 10 years of elevated glucose levels to get complications,” he says. “So the skin may be a better measure because it is a better long-term marker [of the accumulated damage].”
By having a window into what is happening at the tissue level, Buckingham suggests that clinicians could do a better job making treatment decisions. Additionally, as a simple screening tool, Buckingham could see the device being applied in public health screenings, clinicians’ offices, and even pharmacies. “I don’t think people would consider it as a gold standard because they don’t have that much experience with it, but it might be something that could be used as a front-line, noninvasive, relatively simple initial screen.”
That, in fact, is exactly how Donald Moore, MD, would like to use the device if clinical testing ultimately proves that the approach is valid. Moore is a provider with Western Rockingham Family Practice in Madison, NC, and has been watching development of the technology. “Being able to screen for diabetes in an easy way without having [to use needles] would be an incredible advantage,” says Moore, noting that he sees patients with undiagnosed diabetes all of the time. “We have an industrial nurse, and we are always doing health fairs, so I can really see it as very beneficial in helping to diagnose diabetes at an earlier stage and getting people in to be treated and educated.”
However, Moore says that winning provider buy-in to the approach will be a tough hurdle. “If providers see the numbers are going to compare favorably [with conventional testing], and maybe even pick up new people in a more sensitive way . . . then I think physicians will buy into it, but the real bottom line is getting reimbursement for doing the test.”
Anticipating that reimbursement will take time, Maynard suggests that the first applications of the Scout system will likely be in private pay settings. However, he says that potential application of the device is huge. “There is a large number of people with undiagnosed diabetes, and there is an even bigger group of people who have prediabetes,” he says. “If you want to shift the care model from treating the symptoms and complications to preventive medicine—which is what we are going to have to do with diabetes because we just won’t be able to afford it—then you want to pick up people in the prediabetes stage.”
Editor’s note: For more information about VeraLight or the Scout screening system, visit the company’s Web site at www.veralight.com.
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