Diabetes Diagnosis: Do You Have Diabetes and Not Know It?

Diabetes Diagnosis: Three Years After Diagnostic Criteria Changes, Many Uncertain How Best To Test for Diabetes

BOSTON — March, 2000 — Nearly three years after guidelines for diabetes diagnosis were changed by the American Diabetes Association, many people who may have diabetes — and the physicians who treat them — remain unclear as to how diabetes should be diagnosed. An estimated 16 million Americans have diabetes, yet about one-third do not know they even have the disease.

"Certainly from the kinds of questions we get on the phone and particularly now through the Joslin web site, it’s clear that in many circumstances patients and their primary care doctors are not sure what the simplest, most effective and best ways are to test for diabetes," according to John Hare, M.D., Director of Affiliated Programs at Joslin Diabetes Center in Boston. "Physicians also may not be testing high-risk groups most likely to have the disease."

"Yet, as we well know, early diagnosis of diabetes and success getting blood sugars under control can reduce a patient’s risk of diabetes complications such as heart disease, eye problems and kidney disease," says Dr. Hare. "So early diagnosis is really important."

The American Diabetes Association in June 1997 announced new recommendations for how diabetes should be diagnosed. The international ADA Committee studying the issue recommended lowering the number being used to diagnose diabetes for the most common test (the fasting plasma glucose test) employed to identify people with the disease. The ADA's hope was that physicians will identify patients who have diabetes earlier, when the chances for preventing long-term complications through good diabetes management are greatest.

Who Should be Tested

The ADA also recommended that all individuals age 45 and above be tested for diabetes, and if the test is normal, they should be re-tested every three years. Testing should be conducted at earlier ages and carried out more frequently in individuals who are any of the following: obese; have a first-degree relative with diabetes; are members of a high-risk ethnic population (African American, Hispanic, Native American, Pacific-Islander, Asian); have delivered a baby weighing more than 9 pounds; have had gestational diabetes; have high blood pressure; have HDL cholesterol levels equal to or less than 35 mg/dl or triglyceride levels equal to or greater than 250 mg/dl; or who, on previous testing had impaired glucose tolerance or impaired fasting glucose.

How Diabetes is Diagnosed

The ADA recommendations for diagnosing diabetes state that patients be told they have diabetes if any of the criteria below applies:

• Fasting plasma glucose is above 125 mg/dl;
• Diabetes symptoms exist and casual plasma glucose is 200 mg/dl or higher; or
• Plasma glucose is at least 200 mg/dl during an oral glucose tolerance test.

If any of these test results occurs, testing should be repeated on a different day to confirm the diagnosis.

In recent months, the ADA and researchers have noted that diabetes-like complications can develop over time in patients who don’t have diabetes, per se, but do have fasting blood sugars consistently in the 110-125 mg/dl or blood sugars in the 140-200 mg/dl range two hours following a glucose tolerance test.

"Patients will contact us wanting to tell us about the results of a glucose tolerance test, and asking whether the results mean they have diabetes," says Dr. Hare. "A glucose tolerance test — which generally costs more to perform — isn’t always necessary to diagnose diabetes. If the patient is high-risk or has symptoms of diabetes — excessive thirst, frequent urination, tiredness and so forth — the doctor can do a fairly simple plasma glucose test. The patient doesn’t even need to have fasted for this test. If the blood sugar test comes back over 200 mg/dl, the doctor should test again on another day to confirm, but almost certainly the patient has diabetes."

Similarly, patients who don’t have symptoms of diabetes but are in a high-risk category can fast and have the more simple plasma glucose test done in the doctor’s office. "If the blood sugar comes back at 126 mg/dl or higher, the doctor should test again on another day to confirm whether the patient has diabetes."

Tell your doctor if you are high risk

People who have a history of diabetes in their family, or who come from high-risk groups, should be aware of their greater likelihood of developing diabetes and mention it to their physician when visiting for a check-up.

"In today’s healthcare environment, physicians have a very few minutes to give to each patient," notes Dr. Hare. "Diabetes testing is not part of the routine blood work that a physician may do as part of a physical. So the patient is an integral part of this testing process - - he or she needs to mention to the doctor that they have a family history of the disease, or are in a high-risk category. The doctor may not know about the family history, or may have noted it so far back in the chart that they don’t see it when the patient comes in. The patient needs to ask that the test be done. The patient should then followup with the doctor to find out the results and keep a record of the number over time, like one would do with their cholesterol and blood pressure readings."

If you have diabetes, share this with family and friends who are in high risk categories, and help identify those who have diabetes and don't know it.