Contributions of glucose and hemoglobin [A.sub.1c] measurements in diabetes screening

Objectives: Given the long-term consequences of untreated diabetes, patients benefit from timely diagnoses. Payer policies often recognize glucose but not hemoglobin [A.sub.1c] ([HbA.sub.1c]) for diabetes screening. This study evaluates the different information that glucose and [HbA.sub.1c] provide for diabetes screening. Methods: We conducted a retrospective review of national clinical laboratory testing during 2020 when glucose and [HbA.sub.1c] were ordered for routine diabetes screening, excluding patients with known diabetes, out-of-range glucose, or metabolic syndrome. Results: Of 15.47 million glucose and [HbA.sub.1c] tests ordered simultaneously, 672,467 (4.35%) met screening inclusion criteria; 116,585 (17.3%) were excluded because of diabetes-related conditions or the specimen was nonfasting, leaving 555,882 result pairs. More than 1 in 4 patients 60 years of age or older with glucose within range had an elevated [HbA.sub.1c] level. [HbA.sub.1c] claims were denied more often for Medicare beneficiaries (38,918/65,273 [59.6%]) than for other health plans combined (23,234/291,764 [8.0%]). Conclusions: Although many health plans do not cover [HbA.sub.1c] testing for diabetes screening, more than 1 in 4 glucose screening patients 60 years of age or older with an in-range glucose result had a concurrent elevated [HbA.sub.1c] result. Guideline developers and health plans should explicitly recognize that glucose and [HbA.sub.1c] provide complementary information and together offer improved clinical utility for diabetes screening. KEY WORDS Glucose; Hemoglobin [A.sub.1c]; [HbA.sub.1c]; Diabetes; Screening