search.noResults

search.searching

dataCollection.invalidEmail
note.createNoteMessage

search.noResults

search.searching

orderForm.title

orderForm.productCode
orderForm.description
orderForm.quantity
orderForm.itemPrice
orderForm.price
orderForm.totalPrice
orderForm.deliveryDetails.billingAddress
orderForm.deliveryDetails.deliveryAddress
orderForm.noItems
EDUCATION :: DIABETES


Three things laboratories need to know about HbA1c testing


By Jeannine T. Holden, MD I


t has been several decades since HbA1c testing made its debut in the arena of diabetes management. Since then, this breakthrough test has become a widely used and a highly effective complement to blood glu- cose testing for monitoring longer-term glucose levels in patients with diabetes and/or suspected diabetes. As the use of HbA1c testing has grown, so has the pool of clinical experience and evidence that drives best practices for quality patient care. This includes awareness of those conditions and circumstances that can compromise HbA1c testing’s utility. Attention to these factors helps assure laboratorians and clinicians that the results at the foundation of patient care deci- sions are accurate. To give adequate context to these influences, it is helpful first to understand the mount- ing global healthcare burden resulting from diabetes and the role of HbA1c testing in patient diagnosis and management.


Diabetes: A growing threat


Diabetes is a looming healthcare crisis. The Interna- tional Diabetes Federation (IDF) reported in 2017 that the number of patients with diabetes stood at 425 mil- lion globally—or one in 11 people—and that half of those cases were undiagnosed.1


up from 108 million in 1980, as cited by the World Health Organization (WHO).2


percent of adults 18 years and older had diabetes in 2014 versus 4.7 percent in 1980.2


The current figure is WHO reported that 8.5 This prevalent and


life-threatening condition was the direct cause of 1.6 million deaths in 2016, making it the seventh lead- ing cause of death in the world that same year.2


The


incidence of diabetes is expected to grow. By 2045, IDF estimates state that there will be 629 million people with diabetes in the world—a 48 percent increase from current levels.1


HbA1c testing


The development of HbA1c assays was a significant step forward in diabetes management. HbA1c testing measures glycated hemoglobin, formed when glucose binds to the protein component of hemoglobin, the oxygen-transporting molecule present in red blood cells. Measuring the percentage of glycated hemo- globin in relation to total hemoglobin provides an index of the amount of glucose in the body. Normal HbA1c levels are between four percent and 5.6 percent, while measurements between 5.7 percent and 6.4 per- cent indicate prediabetes and rates above 6.5 percent signify diabetes.3


The use of HbA1c for diabetes management emerged in clinical laboratories around 1977. This was almost a decade after Samuel Rahbar, MD, PhD, discovered an “abnormal, fast-moving hemoglobin band” in a patient sample while looking for hemoglobin variants.4 He reviewed the patient’s history and found she was


52 JULY 2019 MLO-ONLINE.COM diabetic.5


This led Dr. Rahbar to screen an additional 47 patients, all of who had the same hemoglobin.5 The initial discovery served as the basis for subsequent work identifying HbA1c as a significant clinical bio- marker for longer-term glycemic control and paved the way for the type of commercially developed assays still in use today. It was not until just over 40 years after Dr. Rahbar’s initial discovery, however, in 2010, that manufactured tests would become standardized to the point that the American Diabetes Association would recommend HbA1c testing as a standard of medical care in diabetes.6


HbA1c testing has been cited as one of the two most important advances in diabetes management. The other is portable blood glucose meters, used by people with diabetes to self-monitor their glucose levels.7


These portable glucose monitors are now giving way to a new generation of wearable prod- ucts designed to provide patients with continuous glucose monitoring. While these technologies can keep diabetic patients and their physicians apprised of glucose levels, and thereby help minimize the sequelae of suboptimal blood glucose control, they do not replace HbA1c testing’s broader clinical utility; they support diabetes management, but they are not used to diagnose the disease. HbA1c, on the other hand, can be used for both management and initial diagnosis, thereby helping to identify previously undiagnosed patients and underscoring its relevance even in the face of increasing use of continuous glucose monitoring.


HbA1c testing and blood glucose monitoring Because the typical lifespan of a red blood cell is eight to 12 weeks, HbA1c testing provides a longer-term representation of overall blood glucose levels. Fasting plasma glucose and blood glucose testing, in contrast, offer information about a patient’s glucose levels at a given moment. The two types of tests complement each other, and both are used to monitor patients with either type 1 or type 2 diabetes. Type 1 diabetes occurs when a patient’s pancreas is unable to produce insu- lin. For those with type 2 diabetes, the pancreas can produce insulin, but either the body cannot effectively use it, or the amounts may be inadequate to support the body’s needs. Glucose and HbA1c measurements work together to provide both a short-term snapshot and longer-term picture of patient glucose levels. Managing both long-term and short-term glucose levels is critical. Poor long-term control of blood glucose levels is associated with complications such as peripheral vascular disease, blindness, and kidney disease, whereas short-term low blood glucose causes symptoms that include lightheadedness, shakiness, and weakness.8


Untreated, hypoglycemia may result in shock and ultimately, death.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72