Mary Rhee, MD, a physician-researcher with the Atlanta VAMC and Emory University, discusses the use of a glucometer with VA patient Joseph Fields. VA photo by Lisa Pessin

ATLANTA—A test included in nearly all routine blood chemistry panels provides a surprising window on a patient’s future health. The random plasma glucose test—at levels previously considered unremarkable—can predict whether a patient is likely to develop diabetes in the next five years, according to a VA study.

Simplifying identification of patients at risk for diabetes is particularly valuable for primary care providers in the VA who manage a large patient panel with an elevated risk of the disease. About 12% of all adults in the U.S. have been diagnosed with diabetes, compared to more than 20% of all veterans.2 Among those who receive care through the VA, 1 in 4 has a diagnosis of diabetes.

The actual rate of diabetes is almost certainly higher, lead author Mary Rhee, MD, an endocrinologist at the Atlanta VAMC and professor at the Emory University School of Medicine, said about the PLoS One study. 1 “In the general population, about 24% of those with diabetes are undiagnosed. It’s likely to be the same at the VA.”

Screening guidelines have been developed to diagnose a greater number of patients with diabetes more quickly. According to the American Diabetes Association guidelines, patients age 45 or older should be screened at least every three years, and younger patients should be screened if they are overweight or have an additional risk factor for diabetes. Patients at high risk or with identified prediabetes should be screened annually, Rhee said.

Many people who should be screened aren’t. “Because people are not being screened optimally, we thought perhaps it would be good to identify other clinical factors for those at higher risk for having diabetes,” Rhee told U.S. Medicine. The goal was to find an already available indicator or a pre-existing signal that could be used in a new way.

“People generally don’t like to do extra things,” Rhee said. The fasting blood glucose or oral glucose tolerance tests require planning for the patient to be fasting and take some time. Even the straightforward HbA1c test demands an extra step.

“If you happen to have a chemistry panel that includes RPG—and nearly all do—this can be an opportunistically available test to identify patients at high risk,” she explained. “The benefit is that you don’t have to order another test. People go to see their doctors and have a routine chemistry panel which most providers will order, and the glucose test will just be sitting there.”

That’s important as the test can provide a critical signal to providers to conduct additional follow-up and to talk with veterans about reducing their risk and does not require any additional effort on the part of patient or provider.

The RPG has been the Rodney Dangerfield of tests; it’s been largely ignored for years. Because it is part of a routine blood panel, patients are not necessarily fasting and providers have no idea how long before the test a patient last ate. As a result, it’s been challenging to know how to interpret the results.

“Often it’s ignored unless the levels are notably high or low. We don’t know how helpful they are or not unless it’s 200 or higher, which would be diagnostic of diabetes if the patient is also having other symptoms of high glucose,” Rhee noted. “If it’s below 200, we haven’t known how to interpret the results. Did the patient have a Slurpee with ice cream before the test? We don’t know.”

It turns out that numbers much lower than 200 provide critical information and really shouldn’t be ignored, however.

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