Of the almost 24 million Americans who have diabetes, nearly a quarter don't know it.1 Until recently, a diabetes diagnosis had to be made on the basis of the results of two tests-two fasting plasma glucose tests, two oral glucose tolerance tests, or one of each-performed on separate days that are close in time.2 Both involve significant planning, with the former requiring the patient to fast for at least eight hours beforehand and the latter taking several hours to complete. It's likely that the inconvenience associated with these tests dissuades some people from undergoing them, hampering the identification of many who need treatment.
When experts from the American Diabetes Association (ADA), the International Diabetes Federation, and the European Association for the Study of Diabetes came together in 2008 to determine how to improve the diagnosis of diabetes, convenience was one of the factors they considered. The committee compared these two tests with the hemoglobin AIc assay and reported its recommendation on June 5 at the ADA's 69th Scientific Sessions: the hemoglobin AIc assay should be used whenever possible to diagnose diabetes.
The committee found that the level of hemoglobin AIc (formerly known as glycosylated hemoglobin), which measures glycemic control over the previous two to three months, may be a better tool for diagnosing diabetes than the fasting plasma glucose test or the oral glucose tolerance test.3 David M. Nathan, MD, chairperson of the committee, said in a press release that the hemoglobin AIc assay provides values that vary less than those obtained with the other tests.4 In my own practice, I've noticed that many patients have trouble scheduling fasting blood work. The hemoglobin AIc assay can be done at any office visit, making it much easier for patients-and more likely that testing will be done.
The committee determined that an assay result of 6.5% or higher is the most reliable indicator of the presence of diabetes. Patients with a level of 6% to 6.4% are considered to be at high risk for developing diabetes.
The ADA recommends screening for diabetes in patients who are overweight and have one of the following risk factors5: physical inactivity, a family history of diabetes, an ethnic predisposition to diabetes, gestational diabetes or delivery of a baby weighing more than 9 lbs., polycystic ovarian syndrome, cardiovascular disease, hypertension, hyperlipidemia, a history of impaired glucose tolerance or impaired fasting glucose, comorbidities associated with insulin resistance, and being 45 years of age or older.
Because the hemoglobin AIc assay cannot be used in patients with conditions that involve red blood cell turnover such as hemolytic anemia or who have had a recent blood transfusion, and because its cost is prohibitive in some parts of the world, the fasting plasma glucose and oral glucose tolerance tests will still be used in some cases. Regardless of which test is used, according to Richard Kahn, PhD, former chief scientific and medical officer of the ADA, "The diagnosis of diabetes should be confirmed with a repeat of the same test performed on a different day" to guard against laboratory errors.
NURSING PRACTICE
How can nurses help diagnose and manage diabetes?
* Encourage high-risk patients to be screened.
* Counsel patients with hemoglobin AIc levels of 6% to 6.4% to consider lifestyle changes to reduce their risk of developing diabetes.
* Ensure that patients with diabetes know their hemoglobin AIc levels, their pre- and postmeal blood glucose targets, and the steps to take to achieve these targets.
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