Controversy erupts over new diagnosing criteria
Will low-level diagnosis invite discrimination?
It has taken a couple of years for the experts to get around to writing their opinions about the change in diagnostic baselines for diabetes recommended by the American Diabetes Association in Arlington, VA, and the World Health Organization in Geneva.
That controversy has suddenly become heated in the past couple of months. In an article and an editorial published in the April 7 issue of the Journal of the American Medical Association, a member of the original expert committee, which recommended re-setting the diagnostic criteria, and an epidemiologist at the Centers for Disease Control and Prevention in Atlanta went head to head over the benefits of lowering the bar.
Mayer Davidson, MD, who is a member of the American Diabetes Association expert committee on the diagnosis and classification of diabetes mellitus, argues that diabetes should not be diagnosed at plasma glucose levels under 140 mg/dl unless the patient also has an elevated glycosalated hemoglobin (HbA1c). Davidson is also a professor of medicine at the University of California at Los Angeles and director of the clinical trials unit at Charles R. Drew University of Medicine and Science, also in Los Angeles.
Patients without elevated HbA1Cs should be diagnosed as having impaired fasting glucose, Davidson says, so early intervention can take place "without subjecting these persons to the potentially negative insurance, employment, social, and psychological consequences of a diagnosis of diabetes mellitus.
"The decision of where to draw the line is somewhat arbitrary," he says. "In fact, the recommendation for diet and exercise modification would be the same whether a person has been diagnosed or not."
Using data from NHANES III and Meta-Analysis Research Group, Davidson and his colleagues found 86.7% of patients diagnosed with impaired fasting glucose based on the old criteria (140 mg/dl) had HbA1cs in the normal range, and diabetics diagnosed under the old criteria, 18.6% were in the normal HbA1c range.
Davidson also argues that many patients now fall into a "gray area" since testing glycosalated hemoglobin (HbA1c) is now considered a more accurate gauge of long-term plasma glucose than the two-hour glucose tolerance test. "Sixty percent of the people with OGTT results over 200 mg/dl have a normal HbA1c," says Davidson, who was one of the early proponents of using the HbA1c test as a standard in the early 1990s.
Earlier interventions, less complications
Because of the new criteria, more people will be diagnosed with diabetes. In addition, less people with diabetes will go undiagnosed, resulting in earlier interventions and more potential to prevent complications, says Frank Vinicor, MD, MPH, director of the division of diabetes at the centers for Disease Control and Prevention (CDC) in Atlanta, who wrote a JAMA editorial opposing Davidson’s findings.
In the editorial, Vinicor wrote, "It is important not to tell a person that diabetes is present when it is not; likewise, to not identify diabetes when it exists is to ultimately deny benefits of improved metabolic control."
He suggests the appropriate way to address insurance and employment considerations for patients with diabetes is not by lowering the diagnostic criteria, but the way to handle this is to deal with the insurance companies. (Deal with them how?)
Vinicor agrees that a large number of people, perhaps as many as two million, fall within the "gray area" between the old and new criteria.
He says the ease of testing will encourage doctors to order the HbA1c test more often, resulting in more diagnoses. "These were people who always had diabetes, we just didn’t know about them," Vinicor says.
The increased numbers are unlikely to affect funding for diabetes research, he says, because "federal legislators don’t respond only to the size of a problem."
[Mayer Davidson can be reached at (323) 357-3439 and Frank Vinicor at (770) 488-5000.]
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