Repeated hemoglobin A1C ordering in the VA Health System

Hemoglobin A1c (HbA1c) is used to assess glycemic control in patients with diabetes. While underuse of HbA1c testing has been well studied, potential overuse is poorly characterized.

Our objective was to examine the frequency of HbA1c testing in an integrated delivery system. We conducted a retrospective study of administrative data of 130,538 patients with newly diagnosed diabetes receiving care in the Veterans Administration Healthcare System during 2006 and 2007 (mean age 64.1 years, 97.3% male). Our main outcome measures were the proportion of patients receiving repeat HbA1c testing within 30 and 90 days and the proportion of patients receiving more than 4 repeat tests within 12 months of their initial HbA1c.

Overall 8.4% of patients (N = 11,003) received at least one repeat HbA1c within 30 days of their initial test and 30.8% (N = 40,162) within 90 days. A significantly higher proportion of patients with poor diabetes control received a repeat test within 30 days (14.7%) than patients with intermediate control (9.1%) or good control (6.8%) (P < 0.01). Overall, 4.2% of patients (N = 5,468) received more than 4 repeat HbA1c tests and 0.4% received more than 6 (N = 479). In logistic regression models, receipt of more than 4 repeat HbA1c tests was more common among patients age 50-70 years (compared to younger and older patients), whites (compared to blacks and Hispanics), and patients manifesting complications of diabetes (P < 0.01 for all).

Repeat HbA1c testing appears to occur somewhat more frequently than is warranted.