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Blood Test Could Catch Undetected Diabetes

Screening could lead to earlier medical care for millions, researchers say

MONDAY, Jan. 14, 2002 (HealthDayNews) -- A simple screening test could raise a warning flag about diabetes, even for people who are receiving medical care for other conditions, a new study says.

Researchers in North Carolina report a surprising number of middle-aged patients may have undiagnosed diabetes, and they suggest that using the screening test on patients with several risk factors for diabetes could catch the disease early, before serious complications develop.

An expert familiar with the test says it might lead to earlier medical treatments. The study appears in the January issue of the Journal of General Internal Medicine.

Diabetics don't produce or don't properly use the hormone insulin, which is critical to the body's use of food for fuel. Diabetes affects roughly 6 percent of the U.S. population, but experts estimate a third of the cases – or 5 million people – go undiagnosed.

Previous research into undiagnosed diabetes has looked primarily at the general population. However, Dr. David Edelman, lead investigator on this latest study, wanted to see how often diabetes went undiagnosed in patients already receiving medical attention.

"It's still amazing how many patients out there have diabetes and don't know it," says Edelman, a research associate at the Durham Veterans' Affairs Medical Center in Durham, N.C.

The screening method Edelman and his colleagues chose is called the hemoglobin A1c (HgA1c) test. It's the standard test used in managing patients with existing diabetes because it gives doctors a glimpse of a patient's blood sugar levels over the previous three months.

Another test, which is called the blood glucose test and requires patients to prick their fingers, is more sensitive than the HgA1c test, but it only measures blood sugar levels at the time of the test.

The researchers screened 1,253 patients who made regular visits to the medical center. The patients were primarily men, and they were between the ages of 45 and 64. None had ever been diagnosed with diabetes.

After administering the screening test, the researchers performed the blood glucose test on those patients whose screening test raised concerns about diabetes.

"We found a prevalence of about 4.5 percent of our patients who had unrecognized diabetes," says Edelman. "What's interesting about that is that that's roughly comparable to what you would see in the population at large in this age group."

Edelman says the finding challenges the idea that people who don't see doctors are more likely to have unrecognized diabetes.

The researchers also found three risk factors for unrecognized diabetes: hypertension, weighing 20 percent more than one's ideal body weight, and a family history of diabetes. They also found that virtually none of the patients without those factors had diabetes, meaning the test could be limited to patients with the risk factors.

"The testing and follow-up is not cheap in terms of time or money," explains Edelman. "If you can find a population of patients who you really don't need to test, that's helpful."

Finally, the researchers found 61 percent of the patients diagnosed with diabetes also required treatment for hypertension and high cholesterol.

Edelman stresses these patients had fairly serious trouble with blood pressure and blood sugar levels. "It's not a problem of people with very mild disease flying under the radar," he says.

He adds that if an HgA1c test did not point to diabetes, but a doctor still suspected a patient may have the disease because of a variety of risk factors, the more sensitive blood glucose test could still be done.

Randie R. Little, a research associate professor of child health at the University of Missouri School of Medicine, has studied undiagnosed diabetes in the U.S. population. She says the HgA1c test "could be a useful screening test."

"Diabetes can go undiagnosed in adults for many years," says Little. "Sometimes, by the time people are identified, they already have some complications."

The longer the disease goes untreated, she says, the higher the risk of complications, including kidney and heart problems and blindness.

"It is important to diagnose it early," says Little. "If you make certain lifestyle changes, like losing weight and exercising, you can really change the outcome or delay the onset."

What To Do: Take this true-or-false quiz on the HgA1c test from the National Diabetes Education Program. For general information about diabetes, visit the American Diabetes Association or the International Diabetes Federation.

SOURCES: Interviews with David Edelman, M.D., research associate, Durham Veterans' Affairs Medical Center, assistant professor, Duke University Medical Center, Durham, N.C.; Randie R. Little, Ph.D., research associate professor, Department of Child Health, University of Missouri School of Medicine, Columbia, Mo.; January Journal of General Internal Medicine
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