The Impact of Self-Monitoring Blood Glucose Adherence On Glycemic Goal Attainment in an Indigent Population, With Pharmacy Assistance

Abstract

Self-monitoring of bood glucose alone is not a good predictor of HbA_1c goal attainment. Health plans might benefit from formulary restrictions to provide more cost-effective care, without negatively impacting glycemic control. And by using targeted inteventions, healthcare providers could help maximize SMBG's clinical benefit for patients who receive test strips. Self-monitoring of blood glucose (SMBG) can be an important tool in diabetes treatment, both for patient self-management and for guiding clinicians regarding medication adjustments. Evidence supports the association of SMBG with clinical outcomes in patients with type-1 diabetes mellitus (T1DM) although it is mixed for patients with type-2 diabetes mellitus (T2DM). The cost of SMBG comprises a substantial portion of the total cost for patients with diabetes, and test strips are one of the main expenditures of the University of North Carolina Medical Center Pharmacy Assistance Program (PAP), which provides medication coverage, including test strips, to indigent patients who have no pharmacy insurance. The objective of this study is to evaluate the utility of SMBG based on the impact of test-strip adherence on glycemic goal attainment in an indigent population that is provided with low-copay test strips. This retrospective cohort study included patients with T1DM or T2DM who were enrolled in PAP in 2016 and who received a prescription for test strips during the 90 days prior to hemoglobin A1c (HbA_1c) measurement. Adherence was defined as the proportion of days covered (PDC) > 0.8. Of the 498 patients encountered, 20% of the adherent group (n = 245) and 25% of the nonadherent group (n = 253) had a goal of HbA_1c < 7% (P = 0.24). There were no differences in mean HbA_1c between the groups, except in the multiple daily injections (MDI) of the insulin subgroup (8.9% vs. 9.6%, P = 0.009). The adherent group was 80% less likely to have a diabetes-related hospitalization (odds ratio [OR], 0.2; 95% CI, 0.04-0.92). The total test-strip cost to PAP was more than $200,000. In conclusion, in an indigent population, adherence to SMBG does not correlate with glycemic goal attainment and imposes a substantial cost burden on the healthcare system.

Keywords: Self-monitoring of blood glucose (SMBG); adherence; cost savings; diabetes mellitus; formulary management; indigent population.

Figure 1

Average HBA_1c in Insulin Use and Diabetes Diagnosis *MDI = multiple daily injections *P = 0.009