Single blood sample could be sufficient for diabetes diagnosis
medwireNews: Researchers studying the ARIC cohort have found that virtually all people with elevated fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) in the same blood sample went on to develop diabetes.
The findings are published in the Annals of Internal Medicine, in which the authors of a linked editorial say that the researchers “offer an innovative and practical use of a single blood sample at 1 visit, rather than 2 samples obtained at 2 visits, to confirm the diagnosis of diabetes.”
KM Venkat Narayan and Ram Jagannathan, both from Emory University in Atlanta, Georgia, USA, add that the “approach has appeal, especially for resource-challenged settings, but it needs replication in other populations before becoming accepted clinical practice.”
The positive predictive value of the two-in-one test was low for the prediction of diabetes within 5 years, at 39.7%, suggesting many false positives. However, Elizabeth Selvin (Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA) and co-workers found that this value increased with longer follow-up, to 88.7% at 15 years.
Indeed, they say that the diabetes risk associated with having simultaneously increased FPG and HbA1c was “extraordinarily high,” adding that almost all of these participants “who remained alive were subsequently diagnosed with diabetes.”
The negative predictive value was 99.0% at 5 years and 81.8% at 15 years, indicating that false-negative results were “not a major concern.” The negative predictive value was likewise high for people with any positive finding (ie, elevated FPG or HbA1c or both), but the positive predictive value was lower, at 21.0% and 71.1% at 5 and 15 years, respectively.
However, sensitivity for diabetes was higher with any positive finding than with simultaneous positive findings, and so the researchers highlight that people with isolated FPG or HbA1c increases should be retested at a later timepoint, in line with current recommendations.
The diabetes risk analysis involved 12,199 ARIC participants with valid data, increasing to 13,346 for analysis of all-cause mortality. In this latter analysis, the research team found an increasing mortality rate, from 17.5 per 1000 person–years for people without diabetes, to 26.9, 30.1, and 41.8 per 1000 person–years for those who had, respectively, a single positive glucose finding, a double positive finding, or confirmed diabetes at baseline.
There were similar patterns for rates of chronic kidney disease, cardiovascular disease, and peripheral artery disease, prompting the editorialists to stress that “hyperglycemia exists on a continuum,” so just a single adverse glucose test can indicate increased risk.
“Early detection and diagnosis of diabetes are critical for appropriate initiation of interventions to prevent or delay complications,” write Narayan and Jagannathan. “Simplifying methods to identify and confirm diabetes will facilitate this important clinical and public health priority.”
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