Background: Diabetes disparities are well-documented. Racial/ethnic minority groups consistently have worse self-care and higher A1cs relative to non-Hispanic whites (NHWs). Less known are the underlying mechanisms contributing to disparities in diabetes outcomes that, if addressed, would mitigate disparities in A1c.
Objective: We tested whether insulin adherence is a mechanism underlying racial/ethnic disparities in A1c.
Methods: Adults (age 18-75 years) with type 2 diabetes (T2D) self-selected to be in a randomized control trial comparing inhalable, ultra-rapid-acting insulin (Afrezza) with One Drop vs. injectable, rapid-acting insulin with One Drop. Eligible persons completed an online survey and NGSP certified A1c test. Survey items collected demographic information and responses to the Adherence to Refills and Medications Scale for Diabetes (ARMS-D) administered for insulin only. SPSS and PROCESS v3.0 were used for descriptive statistics and unadjusted and adjusted mediation models with bootstrapped (10K) CIs for tests of indirect effects.
Results: Participants (N=269) were 50 & 11 years old, 51% male, 30% non-white, with 13 & 8 years since a T2D diagnosis, and A1c 8.8% & 1.8%. Compared to NHWs, non-whites were less adherent to their insulin regimen (ARMS-D = 35.4 vs. 37.2, p<.05) and had a higher A1c (9.2% vs. 8.6%, p < .05). Among younger adults (<49.94 years old), not taking enough insulin was a mechanism linking non-white race/ethnicity to having a higher A1c (unadj. coef.=.40, 95% CI: .09, .79; adj. coef.=.33, 95% CI: .01, .77). Among people over age 50, there was no indirect effect of non-white race/ethnicity on higher A1c via less adherence to insulin.
Discussion: Reducing disparities in insulin adherence may reduce disparities in A1c for younger adults, but not older adults. Other mechanisms underlying diabetes disparities may be age- or cohort-specific. Understanding these nuances can inform interventions aimed at reducing disparities in diabetes.
L. Sears: Employee; Self; Informed Data Systems Inc.. Research Support; Self; MannKind Corporation. A. Hirsch: Employee; Self; One Drop. Research Support; Self; MannKind Corporation. J. Dachis: Stock/Shareholder; Self; One Drop. Board Member; Self; One Drop. Employee; Self; One Drop. J. Raymond: None. M. Heyman: Employee; Self; One Drop. R. Head: None. C.Y. Osborn: Employee; Self; One Drop. Research Support; Self; MannKind Corporation. Stock/Shareholder; Self; One Drop.