Egede LE (Charleston REAP), Mueller M
(Charleston REAP), Gebregziabher M
(Charleston REAP), Echols CL
To examine longitudinal differences in glycemic control by race/ethnicity in veterans with type 2 diabetes.
Data on 8,813 veterans with type 2 diabetes were analyzed. A person-period data set for each subject to cover three-month intervals (36 time intervals) from April 1997 to March 2006 was created. Diabetes and other comorbidities were based on ICD-9 codes using validated algorithms. HbA1c values for each subject in the three-month time interval were used for analysis. Glycemic control was defined as good (HbA1c <7%), or poor (HbA1c > 7%) for each three-month time interval. Analysis was focused on non-Hispanic Whites (NHW) and non-Hispanic Blacks (NHB). Subjects were followed from time of entry into the study until death, loss to follow-up, or March 2006. Generalized linear mixed models (PROC GLIMMIX, SAS 9.13) were used to assess whether glycemic control (poor control vs. good control) changed over time and if change in glycemic control varied by ethnic group. We examined whether the risk of having poor control increased over time and whether the patterns of change in the risk of poor control was the same for NHB and NHW after controlling for potential confounding variables. Several individual growth curve models were considered to examine the unique trajectories of individuals and ethnic groups in glycemic control from the repeated measures data. All models contained glycemic control as response variable, time and race/ethnicity as primary variables of interest, and a person-level random effect to account for within-individual correlations. A final model was fitted to examine the effects of race/ethnicity, time, gender, employment, marital status, and comorbidities (CHD, hypertension, stroke, and depression).
64% of the sample were NHW and 36% were NHB. Mean age was 67 years. 97% were men. 64% were married and 50% were unemployed. Mean follow-up period was 4.6 years. In unadjusted analysis, the proportion of NHB veterans with poor glycemic control was consistently higher over time, but the patterns of change in the glycemic control proportions over time did not depend on race. In the final fixed effects model, NHB veterans were almost twice as likely to have poor glycemic control over time compared to NHW veterans (OR: 1.83, 95% CI:[1.7; 12.0], p < 0.0001).
Non-Hispanic Black veterans with type 2 diabetes have an almost 2-fold increased odds of having poor glycemic control compared to their non-Hispanic White counterparts over ~5 years of follow-up.
This is one of the first studies to show that racial/ethnic differences in risk of poor glycemic control persist over time. Further studies are needed to identify explanatory factors and test effective interventions to eliminate ethnic disparities in glycemic control among veterans with type 2 diabetes.