Regional, geographic, and racial/ethnic variation in glycemic control in a national sample of veterans with diabetes

OBJECTIVE - We performed a retrospective analysis of a national cohort of veterans with diabetes to better understand regional, geographic, and racial/ethnic variation in diabetes control as measured by HbA_1c. RESEARCH DESIGN AND METHODS - A retrospective cohort study was conducted in a national cohort of 690,968 veterans with diabetes receiving prescriptions for insulin or oral hypoglycemic agents in 2002 that were followed over a 5-year period. The main outcome measures were HbA_1c levels (as continuous and dichotomized at ≥8.0%). RESULTS - Relative to non-Hispanic whites (NHWs), HbA_1c levels remained 0.25% higher in non-Hispanic blacks (NHBs), 0.31% higher in Hispanics, and 0.14% higher in individuals with other/unknown/missing racial/ethnic group after controlling for demographics, type of medication used, medication adherence, and comorbidities. Small but statistically significant geographic differences were also noted with HbA _1c being lowest in the South and highest in the Mid-Atlantic. Rural/urban location of residence was not associated with HbA_1c levels. For the dichotomous outcome poor control, results were similar with race/ethnic group being strongly associated with poor control (i.e., odds ratios of 1.33 [95% CI 1.31-1.35] and 1.57 [1.54-1.61] for NHBs and Hispanics vs. NHWs, respectively), geographic region being weakly associated with poor control, and rural/urban residence being negligibly associated with poor control. CONCLUSIONS - In a national longitudinal cohort of veterans with diabetes, we found racial/ethnic disparities in HbA_1c levels and HbA_1c control; however, these disparities were largely, but not completely, explained by adjustment for demographic characteristics, medication adherence, type of medication used to treat diabetes, and comorbidities.