An international expert panel assembled by three leading diabetes organizations has recommended the use of the A1C assay for the diagnosis of diabetes. In its report, the committee states its hope that the recommendation “will serve as a stimulus” to the discussion of appropriate screening for and diagnosis of this prevalent metabolic condition.
But what impact would this recommendation—if widely implemented—have on primary care practice? And will it be widely implemented, as has largely been assumed? As Sandra Drozdz Burke, PhD, APRN, CDE, BC-ADN, a member of the board of directors of the American Association of Diabetes Educators, points out, “It’s a report. And nothing is going to be done about it until after the constituent groups have a chance to review it and make some decisions…. We generally don’t change practice based on an article.
The Case for A1C
Currently, the standard for the diagnosis of type 2 diabetes is a fasting plasma glucose (FPG) of 126 mg/dL or higher or a random oral glucose tolerance test (OGTT) of more than 200 mg/dL. While these tests have been validated, endorsed, and standardized, they provide a snapshot of a patient’s glycemic control—and not in entirely “real world” conditions.
The FPG test requires the patient to fast for at least eight hours prior to testing. Besides that inconvenience, there are also variances in FPG. “If you’re fasting, you haven’t been challenged for an extended period,” says Scott Urquhart, PA-C, President of the American Society of Endocrine PAs, who practices at Diabetes and Thyroid Associates in Fredericksburg, Virginia. “And the day-to-day variation is roughly 12%. So a patient could be at 112 one day and 98 the next. They were ‘prediabetic,’ and now they’re not.”
For the OGTT, patients must consume 75 grams of sweet drink in five minutes. “Most of us can’t even consume that,” Urquhart points out. By his calculation, the preparation is equivalent to drinking a 20-ounce bottle of soda in five minutes. “That gives you an indication of why it’s often called a glucose stress test—it is quite stressful. And is that a fair comparison to how most people consume daily calories? The answer is, probably not. So maybe that uncovers too many people who wouldn’t be facing that challenge every day.”
By contrast, the A1C assay, as the expert panel notes, “can be obtained at any time [and] requires no patient preparation.” Besides ease of use, a more important argument in favor of the A1C assay for diagnosis of diabetes is the fact that it provides a long-term overview of a patient’s glycemic state.
“It doesn’t give a one-day look at the blood sugar,” says Geralyn R. Spollett, MSN, ANP, CDE, an adult nurse practitioner and Associate Director of the Yale Diabetes Center. “It’s an accumulation of two to three months’ averaging of blood sugar. Hopefully, it would catch those patients who come in and their blood sugar looks OK that day but for whom there is some kind of symptomology suggestive of diabetes.”
A Matter for Debate
One prevailing theory is that these benefits might encourage clinicians to use the A1C assay, resulting in the identification of more patients who are currently diabetic but unaware of it. Statistics indicate that approximately 25% of persons in the United States with type 2 diabetes are undiagnosed.
“It very well could be that this is a nice alternative to what we’re already doing,” Burke says, “since what we’re already doing is only capturing 75% to 80% [of diabetes cases].”
But can the health care system accommodate those additional patients, who will require treatment not only for their glycemic issues but also for comorbidities such as hypertension and dyslipidemia?
“This is going to help us catch those that need to be diagnosed,” Urquhart says. “But are we going to be able to handle the 50% [of diabetic patients] who aren’t being managed properly now, and then throw these [new cases] on top of them?”
It’s one of many debating points that the recommendation has raised. The committee acknowledges that the A1C assay will not be an accurate measure for patients with hemoglobinopathies; will providers always know which patients have such traits? While some assay methods can correct for these factors, will clinicians—particularly in primary care—have access to them?
Other questions relate to A1C values and how clinicians will interpret them. Burke, who is vice-chair of the Older Adults Working Group of the National Diabetes Education Program, points out that there are not currently age-specific A1C targets. “Even though we know that A1C increases with age, they’re still recommending a universal target of 6.5% as a diagnostic value,” she says. “Is that going to give us false-positives in some populations?”