Utility of HbA(1c) levels for diabetes case finding in hospitalized patients with hyperglycemia.

OBJECTIVE We evaluated the role of a single measurement of HbA(1c) in a diabetes case finding in hospitalized patients with random hyperglycemia at admission. RESEARCH DESIGN AND METHODS From 20 March to 31 July 2000, 508 patients admitted through the emergency department of one hospital were tested for random hyperglycemia (plasma glucose [PG] >125 mg/dl). Consenting patients with hyperglycemia (without preexisting diabetes or on corticosteroids) underwent testing for HbA(1c) levels, two fasting PG levels, and an outpatient oral glucose tolerance test (OGTT) if necessary. RESULTS Of the patients, 50 (9.8%) met the inclusion criteria. Of these, 70% (n = 35) completed the study, and 60% (n = 21) were diagnosed with diabetes. Patients with diabetes had higher HbA(1c) levels than subjects without diabetes (6.8 +/- 0.4 vs. 5.3 +/- 0.1%, P = 0.002). An HbA(1c) level >6.0% was 100% specific (14/14) and 57% sensitive (12/21) for the diagnosis of diabetes. When a lower cutoff value of HbA(1c) at 5.2% was used, specificity was 50% (10/21) and sensitivity was 100% (7/14). CONCLUSIONS In acutely ill patients with random hyperglycemia at hospital admission, an HbA(1c) >6.0% reliably diagnoses diabetes, and an HbA(1c) level <5.2% reliably excludes it (paralleling the operating characteristics of the standard fasting glucose measurements); however, the rapidity of the HbA(1c) level can be useful for diabetes case finding and treatment initiation early in the hospital course.