"So, Dr. Q, do I have it or not?" asked Michael, a 47-year-old man who had just returned from Michigan. His wife, my patient, had brought him in to see me to clarify his diagnosis. He had undergone blood tests in Detroit and was told by his doctor there that he had diabetes. Upset and disbelieving, he refused to take medications. Once in Canada, he went to see his own family doctor. After doing blood tests here, his Canadian physician told him he was fine - and that he did not have diabetes.
"Well, yes and no," I had to reply. It was an unusual situation based on different diabetes-testing criteria in the United States and Canada. The same patient with the same results can be told that he either has or does not have the condition. "Michael, both your doctors are right. In Michigan, you have diabetes. In Toronto, you don't." That didn't seem to help his peace of mind.
Doctors are supposed to be without borders, and the diagnosis of common conditions should not change between countries that share so much. But American physicians are diagnosing diabetes even more aggressively than their Canadian counterparts.
In January, 2010, the American Diabetes Association essentially made it easier for patients to be diagnosed with diabetes by adding the important Hemoglobin A1C test to the diagnostic list. Now, in the United States, a HbA1C level greater than 6.5 per cent means you have diabetes.
Previously, the U.S. gold standard test for diabetes was an overnight fasting sugar (glucose) level of 7.0 millimoles per litre of blood or higher. That still holds for Canada. In fact, Canadian doctors are not even supposed to do the HbA1C test until a person has been fully diagnosed with diabetes by the usual fasting glucose tests. The HbA1C test is used only to track sugar control. It is against current Canadian guidelines to use this as a screening test.
Although no test is perfect, the Americans are onto something. The HbA1C test is a measure of how much sugar has been floating around in your bloodstream for the past three months - how much your organs have been sugar-coated or "candied." That is an important insight. This test reveals your sugar exposure over time, whereas the fasting test measures sugar only at a single point in time.
For this reason, the HbA1C test often picks up high sugar levels long before a fasting glucose test does. That's why the American Diabetes Association recommends this test for screening, which is a major shift in medical thinking.
Many Canadian physicians with patients at high risk for diabetes know about the added value of this three-month sugar test. They have been using it quietly and without official authorization.
But what do you call patients who have a normal fasting sugar - who are not diabetic by Canadian standards - but have a high HbA1C? Such patients are usually given the unsatisfactory label of "pre-diabetic." We tell them that they are diabetics-in-training.
Having pre-diabetes can mean several things, so there is confusion among practitioners. Most important, a pre-diabetic patient in Canada would probably not be given medications and other interventions. Patient themselves do not register its importance. Patients will say, "Yeah, my doctor told me I have a touch of diabetes."
With the tighter testing criteria in the United States, however, the pre-diabetic patient from Canada would be told that he has diabetes. Then a conscientious physician would offer a range of interventions, including diet, exercise, lifestyle change and medications.
Trying to diagnose patients earlier by lowering testing thresholds is a general trend in medicine. Cholesterol levels, blood pressure, salt intake, all the numbers that we recommend to patients keep going down. This is a partial admission by the medical community that the battle against heart disease and diabetes needs to be more aggressive.
Canada should, and probably will, adopt the U.S. diabetes testing standards. About three million Canadians have diabetes now, and six million more are at risk of developing the condition over the next several years. Such people would benefit from knowing their three-month sugar value.
Although we should not rely on any single test for diagnosis, we must use all the tools available. As doctors, we value earlier diagnosis. Then we have a good shot at halting complications - organ damage in the eyes, heart, kidney, blood vessels and nerves, which together kill 41,000 Canadians each year.
Shafiq Qaadri is a Toronto family physician.Report Typo/Error
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