Association Between Baseline Glycemic Markers (HbA1c) and 8-Year Trajectories of Functional Disability

Background: This study assessed whether baseline (i) HbA1c (low [<5.7%], intermediate [5.7%-6.4%], and high [>= 6.5%]) and (ii) glycemic control (7% HbA1c cutoff) in participants with self-reported diabetes were associated with differential 8-year functional disability trajectories. Methods: We used data from the 2006-2014 waves of the Health and Retirement Study for adults aged 50 years and older. Latent class mixture modeling was used to identify distinct functional disability trajectory classes. Multinomial logistic regression analysis examined the association between the newly constructed trajectories and baseline HbA1c levels, and glycemic control, respectively. Results: All participants (N = 5,966) were classified into four functional disability trajectory classes (no disability, low disability, low-increasing, and high-increasing). Participants with elevated HbA1c were at greater risk of being classified into the high-increasing (relative risk ratios = 1.63, 95% confidence interval [CI] = 1.25-2.11) trajectory class. Results showed significant effect modification by age and race. Three functional disability trajectories (no disability, low-increasing, and high-increasing) were identified for participants with self-reported diabetes (n = 1,119). There was no significant association between glycemic control in adults with self-reported diabetes and functional disability trajectory classes. Conclusions: Participants with intermediate HbA1c and elevated HbA1c were more likely to be classified into the trajectories with progressing disability over the study period. More research is needed to better understand the association between glycemic markers and functional disability trajectories. Such research may provide insights into improvements for clinical care, self-management, and public health interventions for both conditions.