Measures of Microvascular Complications Varies Across Racial/Ethnic Groups Over a Seven Year Period: Post-Hoc Analysis of Action to Control Cardiovascular Risk in Diabetes (ACCORD) Trial Data

Introduction: Type 2 diabetes (T2D) microvascular complications is a major public health issue that disproportionately affects people of color in the U.S. and Canada. There is limited understanding of racial/ethnic disparities in the longitudinal natural history of microvascular complications. We aimed to address this gap in knowledge by examining racial/ethnic differences in microvascular complication-related measures over seven years among T2D adults living in the U.S. and Canada. Hypothesis: We assessed the hypothesis that measures of microvascular complications vary by race/ethnic group over a period of seven years. Methods: From 10,251 Action to Control Cardiovascular Risk in Diabetes (ACCORD) (2003-2009) trial participants, we derived 6,683 participants having a baseline and ≥ two years of outcome recordings for our analysis (baseline mean age 62 ± 6.6 years, and 11 ± 7.4 years of diabetes diagnosis). In this longitudinal study, we used T2D microvascular measurements recorded at baseline, yearly for seven years, and during a trial exit period. Neuropathy-related measures analyzed was the Michigan Neuropathy Screening Instrument (MNSI); Nephropathy-related measures included the glomerular filtration rate (eGFR) by four-variable Modification of Diet in Renal Disease equation (ml/min/1.73 m 2 ), urine albumin (mg/dl), and urine albumin : creatinine (mg/g). We examined differences in measurement among Black (n 1 = 1,176), White (n 2 = 4,282), and Other race adults (n 3 = 1,229). We used multigroup latent growth modeling to compare models from fully constrained to unconstrained means, covariances, and residual variances models. Results: MNSI, eGFR, and urine albumin significantly differed across racial/ethnic groups (ΔX 2 MNSI (2) = 231.8, p<0.001; ΔX 2 eGFR (2) = 489.2, p<0.001; ΔX 2 urine-albumin (2) = 194.6, p<0.001). We noticed that at least one of the means and covariances differed across racial/ethnic groups. The average MNSI trajectory for Other race/ethnicity (intercept=1.88, slope=-0.08) were better than that for Black (intercept=2.07, slope=-0.09) and White adults (intercept=2.67, slope=-0.14). The average eGFR trajectories for Black (intercept=88.86, slope=-1.16) and Other race/ethnicity (intercept=85.68, slope=-1.15) were better than that for White adults (intercept=82.59, slope=-1.36). However, average urine albumin trajectories for Black adults were worst (intercept=10.77, slope=0.98) followed by Other race/ethnicity (intercept=9.36, slope=0.73) and White adults (intercept=7.65, slope=0.57). Conclusion: Trajectories of microvascular complication-related measures appear to vary by racial/ethnic group. Other race adults, with primarily consists of Hispanics, appeared to at lower risk of neuropathy for years than Black and White adults. Nephropathy outcomes could vary across racial/ethnic group depending on how nephropathy is defined.