Measurement of Two Biomarkers Predicts Diabetes Risk

The possibility that two different tests from a single blood sample would provide adequate confirmation had not been evaluated.

To address this question, investigators at Johns Hopkins University (Baltimore, MD, USA) examined analytical data from the long-running (more than 35 years) Atherosclerosis Risk in Communities (ARIC) Study that had been accumulated for 13,346 Americans (12,268 without diagnosed diabetes). For the current study, confirmed undiagnosed diabetes was defined as elevated levels of fasting glucose (higher than 126 milligrams per deciliter) and HbA1c (more than 6.5%) from a single blood sample.

Results revealed that among 12,268 participants without diagnosed diabetes, 978 had elevated levels of fasting glucose or HbA1c at baseline (1990 to 1992). Among these, 39% had both (confirmed undiagnosed diabetes), whereas 61% had only one elevated measure (unconfirmed undiagnosed diabetes). The confirmatory definition had moderate sensitivity (54.9%) but high specificity (98.1%) for identification of diabetes cases diagnosed during the first five years of follow-up, with specificity increasing to 99.6% by 15 years. The 15-year positive predictive value was 88.7% compared with 71.1% for unconfirmed cases.

Confirmed undiagnosed diabetes was significantly associated with cardiovascular and kidney disease and mortality, with stronger associations than unconfirmed diabetes.

“The results of our study suggest that the two tests from one blood sample can provide adequate confirmation of diabetes, potentially allowing a major simplification of current clinical practice guidelines,” said lead author Dr. Elizabeth Selvin, professor of epidemiology at Johns Hopkins University. “Doctors are already doing these tests together—if a patient is obese, for example, and has other risk factors for diabetes, the physician is likely to order tests for both glucose and HbA1c from a single blood sample. It is just that the guidelines do not clearly let you use the tests from that one blood sample to make the initial diabetes diagnosis. The bottom line is that this combination of positive results from a single blood sample has a very high positive predictive value for a subsequent diagnosis of diabetes, and also indicates a high risk of typical diabetes complications.”

The study was published in the June 19, 2018, online edition of the journal Annals of Internal Medicine.

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