OBJECTIVES: Even though guidelines suggest glycosylated hemoglobin A1c (HbA1c) testing at least twice a year for diabetics and despite the correlation between long term glycemic control and reductions in overall health care costs and service utilization, studies have estimated that only 75% of diabetes patients receive annual HbA1c screening. The purpose of this study was to examine the relationship between participation in a free HbA1c home-testing program and several individual-specific variables, including age level, gender, income range and disease severity. METHODS: Participants enrolling in the CarePatterns(r) Disease Management Program for Diabetes from January 1, 2003 through June 30, 2003 and who opted to participate in the free home-based HbA1c testing program were included in the study. Allowing sufficient time for test completion and return, Chi-squared (c2) and Cochran-Mantel-Hanzel (CMH) statistics were utilized to examine the relationship between home-testing participation and the independent variables. RESULTS: Of the 2624 home-testing participants, the overall HbA1c test completion rate was 49.5%, with males significantly more likely to complete the test than females (52.3% vs. 46.1%; c2: p = 0.001). Although home-testing participation increased significantly with age (c2: p <0.0001), a significantly lower rate of participation was observed at the highest level of disease severity (c2: p = 0.0006). No significant relationship between participation and income level existed. There was a significant interaction effect between age and gender, with the relationship between gender and home-testing participation reversing as age increased (CMH: p <0.0001). Gender also significantly mediated the impact of disease severity on participation (CMH: p = 0.001), with the impact of increased disease severity occurring only for females (c2: p <0.0001). CONCLUSIONS: This study suggests that significant differences in program responsiveness exist by demographic and condition-specific variables. Strategies to effectively target these segments of lower responsiveness will improve the viability and success of a home-based A1c monitoring program.