Contributions of Glucose and Hemoglobin A1c Measurements in Diabetes Screening

Lee H. Hilborne, MD, MPH, DLM(ASCP); Caixia Bi, PhD; Jeff Radcliff; Martin H. Kroll, MD; Harvey W. Kaufman, MD


Am J Clin Pathol. 2022;157(1):1-4. 

In This Article

Materials and Methods

Deidentified glucose and HbA1c results from individuals tested at 1 of 10 geographically distributed regional laboratories of a national reference laboratory during calendar year 2020 were extracted for analysis. Results were included if glucose and HbA1c tests were ordered simultaneously. Paired results with the ICD-10 diabetes screening diagnosis (Z13.1) were included, except when the test requisition also included an existing glucose abnormality (diabetes [E08-E11], abnormal glucose [R73], or metabolic syndrome [E88.81]) or the specimen was specifically identified as nonfasting. Data were analyzed by age range and sex. Results were considered discrepant if (1) glucose was within the reference interval (<100 mg/dL, 5.55 mmol/L) but HbA1c indicated prediabetes (5.7%-6.4% [39–46 mmol/mol]) or diabetes (>6.4% [46 mmol/mol]) or (2) glucose was in the prediabetes (100–125 mg/dL [5.55–6.89 mmol/L]) or diabetes (>125 mg/dL [>6.89 mmol/L]) range but HbA1c was within the reference interval.[6]

Claims data were used to explore HbA1c denial rates by payer type. Denials for HbA1c testing were examined when submitted with ICD-10 diagnosis code Z13.1 and with the exclusions previously noted. Claims were categorized as Medicare, Medicare Advantage, Medicaid, Managed Medicaid, or commercial insurance. Self-pay and client-billed claims were excluded because they are not adjudicated against payer policies. Also excluded were claims that were not fully adjudicated at the time of the study (eg, in appeal or pending) or denied for reasons other than diagnosis codes submitted.

This study was deemed exempt by the Western Institutional Review Board (Puyallup, WA).