American Diabetes Association
Diabetes_Care_Strobe_Supplemental_Figure_12323.pdf (87.16 kB)

Association of Medication Adherence with HbA1c Control among American Indian Adults with Type 2 Diabetes Using Tribal Health Services

Download (87.16 kB)
posted on 2023-04-17, 20:42 authored by Lisa Scarton, Tarah Nelson, Yingwei Yao, Ashley DeVaughan-Circles, Anatolia B. Legaspi, William T. Donahoo, Richard Segal, R. Turner Goins, Spero M. Manson, Diana J. Wilkie



To examine HbA1c levels and adherence to oral glucose-lowering medication and their association with future HbA1c levels among American Indian adults with type 2 diabetes (T2D) receiving medication at no-cost from a tribal healthcare system. 


Tribal citizens with T2D and who used Choctaw Nation Health Services Authority (CNHSA) and Pharmacies and had HbA1c data during 2017-2018 were included in this study. Medication adherence (proportion of days covered [PDC] ≥ 0.80) was calculated using 2017 CNHSA electronic health record data. 


Of the 74,000 tribal citizens living on tribal lands, 4,560 were eligible. 32% had HbA1c at or below target (≤ 7%); 36% were above target (> 7% to ≤ 9%); 32% were uncontrolled (> 9%) in 2017. Percentage of patients with PDC ≥.80 was 66% for Biguanides, 72% for Sulfonylureas, 75% for DPP-4 inhibitors, and 83% for SGLT-2 inhibitors. The proportion of patients with HbA1c at or below target increased slightly from 32% in 2017 to 42% in 2018. Higher average PDC in 2017 was associated with lower HbA1c levels in 2018 (β=-1.143, p<.001).


Medication adherence was higher than found in previous studies that used self-report methods in American Indian populations, though a smaller proportion of patients had an HbA1c at or below target relative to US adults with T2D. Mediation adherence was associated with improved HbA1c level for most oral glucose-lowering medication classes. Future studies of American Indians should use both longitudinal prescription data from both electronic health record and pharmacy refill data. 


This research was made possible by Grant Numbers 1R01NR020386-01 and U54CA233444, from the National Institutes of Health, National Institute of Nursing Research (NINR) and National Cancer Institute (NCI). SM Manson was supported by Grant Number 1P30DK092923 from the National Institute of Diabetes, Digestive and Kidney Diseases (NIDDK). The contents are solely the responsibility of the authors and do not necessarily represent the official views of the NINR, NCI, or NIDDK. The final peer-reviewed manuscript is subject to the National Institutes of Health Public Access Policy.


Usage metrics

    Diabetes Care


    Ref. manager