Speaking at the annual Scientific Sessions of the American Diabetes Association, where he received the Kelly West Award for Outstanding Achievement in Epidemiology, William H. Herman, M.D., MPH, discussed how the results of population studies of diabetes can help guide clinical and public health practice.
Herman suggested that the glycosylated hemoglobin test, also called the A1C test, may not be suitable for making the diagnosis of diabetes -- although it's essential for the regular management of diabetes in patients who have already been diagnosed.
Instead, he said, blood glucose tests that measure blood sugar levels after a person consumes a special sugary drink are more accurate, and may be better as the definitive diagnostic tool for diabetes, even though they are more expensive and complex to perform. Such tests can show which individuals have impaired glucose tolerance, or IGT -- an inability to process sugar correctly that can foreshadow the later development of diabetes.
And, Herman said, population-level studies also show how screening millions of at-risk people using these tests can be optimized to use money wisely while still detecting abnormal sugar processing at its earliest stages.
Such screening could determine who is in the earliest stages of IGT and diabetes, and allow such people to receive the nutrition, exercise and medication treatments that have been shown in large studies to prevent the development of full-blown diabetes and the many complications that come with it.
Herman, who is the Stefan S. Fajans/GlaxoSmithKline Professor of Diabetes at the U-M Medical School and director of the Michigan Diabetes Research and Training Center, received the Kelly West award for his significant contributions to the field of diabetes epidemiology.
He has led or helped lead numerous large-scale studies of diabetes screening, diagnosis, prevention and treatment, and has led a computer-modeling project that uses real-world data to simulate and predict diabetes patterns and costs.
In all of these studies, he says, he has adhered to a common theme: using epidemiology, or the study of health issues in large populations, to guide clinical and public health practice. Such studies have shown that the level of high blood sugar that is associated with poor health outcomes reflect the underlying conditions of impaired glucose tolerance and diabetes, not just diabetes alone.
"Diabetes diagnosis should be based on fasting glucose and post-glucose load glucose levels, to give a true picture of glucose tolerance," Herman says. "These tests are inconvenient and time-consuming, but they are preferable to the A1C test."
In his talk, Herman presented data from studies showing that African-American and Hispanic people may have higher A1C levels than other ethnic groups, even when their blood glucose levels are similar.
The important point, he says, is that screening tests and diagnostic tests must be used effectively -- and abnormal results should lead to immediate and aggressive intervention to help individuals control their blood sugar through diet, exercise and, if necessary, medication. This is because studies by Herman and others have shown that tight blood-sugar control can dramatically reduce the chance that a person will develop long-term complications of diabetes, or at least delay the onset of those complications.
And with diabetes threatening the eyes, kidneys, limbs, nerves, hearts and blood vessels of millions, the potential to save lives and money through screening and early treatment is massive, he says.
Even as he receives the ADA's West award for his previous work, Herman is leading a number of studies that promise to add more knowledge to society's understanding of diabetes screening and treatment. One of these, the TRIAD study, aims to translate the findings of epidemiological studies into clinical practice in members of managed care insurance plans such as M-CARE, where Herman is Medical Director.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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