Glycated Hemoglobin Testing to Identify Undiagnosed Diabetes Mellitus in the Inpatient Setting

BACKGROUND: Hyperglycemia is commonly seen in hospitalized patients. Glycated hemoglobin (HbA1c) correlates with the average blood glucose level over the previous 8 to 12 weeks. Thus, an HbA1c test offers a longitudinal view that reduces etiologic ambiguity of disease. Screening of HbA1c levels plays an important role in the diagnosis and management of diabetes mellitus in the outpatient setting but remains underused in the evaluation of hyperglycemia with undiagnosed diabetes in the inpatient setting. The underuse of the HbA1c test may be a missed opportunity for early diabetes detection in the hospital. OBJECTIVE: To examine the use of HbA1c tests in identifying previously undiagnosed diabetes mellitus among patients with hyperglycemia in a rural inpatient setting. METHODS: A retrospective review of medical records of hospitalized patients with hyperglycemia in a rural community teaching hospital in the Midwest. Descriptive and inferential statistical methods were used. RESULTS: Medical records of 348 unique patients with hyperglycemia were reviewed. Fifty patients treated for hyperglycemia had medical records with no known history of diabetes (NKHD). Of the 50 patients with NKHD, 31 (62%) had an HbA1c test. Of the 31 patients tested, 6 (19%) had HbA1c levels consistent with the diagnosis of prediabetes, and 18 (58%) had levels consistent with diabetes. Seventeen (55%) of the 31 patients had a discharge diagnosis that included diabetes. Of the 19 patients with NKHD who did not have an HbA1c test, 2 (11%) received a discharge diagnosis that included diabetes. CONCLUSION: Hospitalized patients with NKHD and hyperglycemia are more likely to receive an appropriate diagnosis if HbA1c is measured. Failing to fully use HbA1c tests in the inpatient setting constitutes a missed opportunity to distinguish transient hyperglycemia from chronic disease. The HbA1c level can elucidate the course of dys-glycemia and trigger mechanisms for timely intervention