Tuesday, August 18, 2009

Hemoglobin A1c to Become a Preferred Test for Diagnosing Diabetes

More than 8% of the US population, which means about 24 million people in this country are diabetic. The prevalence of diabetes is increasing and the number of diagnosed cases of diabetes is expected to reach 35 million by the year 2030.

The American Diabetes Association (ADA) along with the European Association for the Study of Diabetes and the International Diabetes Federation, is strongly considering recommendation of using the Hemoglobin A1c (HbA1c) test as a preferred test for diagnosing diabetes. Many physicians have already been using this test either as an alternative screening tool to diagnose diabetes or as an additional confirmation test for diagnosis. The conventional practice has, so far, used fasting plasma glucose and oral glucose tests to diagnose diabetes, but patients and their doctors do not find these tests very user friendly. Back in the year 2003, the International Expert Committee, including ADA did not recommend using the HbA1c as a screening tool to diagnose diabetes, because different clinical laboratories produced variable results and did not have standardized methods of measurement of HbA1c. However, initiatives by National Glycohemoglobin Standardization Program (NGSP) have improved consistency in the measurement of HbA1c by different laboratories. This move has made the experts to re-consider using the HbA1c test as a diabetes screening and diagnosing tool.

According to many experts, including Christopher Saudek, MD, professor of medicine at Johns Hopkins University School of Medicine in Baltimore, this is an easy to use test, which will be able to help diagnose more patients with diabetes, much earlier in the course of the disease. At this time, unfortunately, almost 40% of the cases remain undiagnosed, and one major reason for this is that the test in practice requires overnight fasting, and many patients either do not like fasting or they just forget to fast before the test. Testing of HbA1c does not require patients to fast, and thus, is perceived as easy and convenient.

The experts at the ADA have recommended that the HbA1c of 6.5%, confirmed by plasma glucose-specific test, should be used as a test to diagnose diabetes. The committee has also recommended further follow-up and more testing, when the HbA1c of a patient is tested at 6.0% or more. Some argument is provided by other experts like Davidson and colleagues (Buell C et al. Diabetes care. 2007; 30(9):2233-2235), about the acceptable HbA1c cutoff point for diagnosing diabetes. They believe that people with HbA1c of 6.0% or less should be considered normal, those with a value of 6.1% to 6.9%as pre-diabetics and a value of 7.0% or higher should indicate diabetes.

It is important for us to know that people with any of the following risk factors- obesity, high blood pressure/ hypertension or a family history of diabetes should get tested for their HbA1c, at least twice a year. Using HbA1c test as a screening tool, will help detect diabetes in more people, especially who are at risk and who would otherwise be left undiagnosed. This will help physicians and their patients intervene early and help them formulate optimal treatment strategies.

Testing of HbA1c is now even more easy and simple through dried bloodspot testing introduced by ZRT laboratory. The patients can perform this test at the convenience of their home, without going to a phlebotomist to get their blood drawn. For more details about dried bloodspot testing, visit ZRT website www.zrtlab.com or feel free to email me at skapur@zrtlab.com.