Beware: Home-Use Glucose Monitors Not Ideal in Hospital Surgical Situations

For rapid testing, doctors and hospitals often use the inexpensive glucose meters approved by the Food and Drug Administration for home use, but many are unaware of inaccuracies in those convenient devices that can lead to harmful treatment errors, particularly ones resulting in very low blood sugar values.

Mark J. Rice, M.D, a University of Florida College of Medicine anesthesiologist is leading a push to let fellow physicians know about the shortcomings of the home glucose meters in hospital settings, and to call the FDA's attention to the need for better regulation surrounding their use clinically.

"They may be faster and cheaper, but they're not always accurate," said Dr. Rice, who has investigated the devices. "They were regulated and approved for home use, then in stealth fashion they ended up in the hospitals."

Rice presented his findings on the technology, accuracy and regulation of glucose measurement devices to fellow physicians at the University Hospital Zurich Institute for Anesthesiology, in Switzerland.

While useful in home settings, the meters are prone to errors from a number of factors, including the presence of other chemicals or medications in the blood, and health conditions such as anemia, and that can cause problems in hospital settings. If a meter gives an inaccurately high reading, for example, doctors might unnecessarily give a patient insulin to lower blood glucose, but that can make the levels truly too low and cause detrimental effects on the central nervous system. On the other hand, too-high levels can impair wound healing and alter consciousness.

One Centers for Disease Control and Prevention study found that on average, readings from some over-the-counter devices differed by as much as 32 percent from values obtained in a central laboratory.

Rice recommends that physicians confirm abnormal blood glucose meter readings using central laboratory measurements, and refrain from using the devices in clinical trials that call for accurate glucose measurements.

The issue of keeping tight control over blood sugar levels before, during and after surgery has been controversial. A decade ago, a report in The New England Journal of Medicine indicated that tightly controlling blood glucose in the intensive care unit might reduce death rates. In response, the American Diabetes Association urged reining in blood sugar levels in critically ill patients, and doctors and hospitals have worked hard to comply.

More recently, however, studies suggest that tight control of blood glucose, as it is now performed, is associated with increased occurrence of abnormally low blood sugar levels, called hypoglycemia, and death among adults in intensive care units, and that the general population of critically ill adults might not actually benefit.

Surgical patients might experience fluctuations in blood sugar levels for various reasons. Some might have pre-existing -- sometimes undiagnosed -- diabetes. In addition, factors such as fasting before surgery, disruption of medication regimens, taking certain medicines, and stress can affect blood sugar levels.

"The problem is, how do you measure that?" Rice said. "Physicians can send patient samples to a central laboratory for testing then wait for the results. Or they can use the convenient meters right at the bedside and get results within seconds."

"Turnaround time has got to be short in order to have optimal clinical benefit," said Peterfreund, who wrote an editorial discussing Rice's Anesthesia & Analgesia paper. "With point-of-care devices, the turnaround time is very rapid … of course if it's not accurate it doesn't help you at all."