Cost-Related Insulin Underuse Is Common and Associated with Poor Glycemic Control

Abstract

Insulin is an essential medicine for people with diabetes (DM), but increasing prices have threatened its affordability. We examined the prevalence of and factors associated with cost-related insulin underuse.We administered a cross-sectional survey to patients with DM prescribed insulin at Yale Diabetes Center (YDC). Our primary outcome was cost-related underuse in the past 12 months, defined by a positive response to any 1 of 6 questions: Did you ⋯ 1) Use less insulin than prescribed 2) Try to stretch out your insulin 3) Take smaller doses of insulin than prescribed 4) Stop insulin 5) Not fill an insulin prescription 6) Not start insulin ⋯ because of cost? We examined the association of cost-related underuse with HbA1c >9% using logistic regression controlling for age, sex, age, DM duration, and income.Out of 354 patients prescribed insulin who had YDC visit in July 2017, 199 (56.2%) completed the survey (50.8% female, 60.8% white, 41.7% type 1). Of these patients, 51 (25.5%) reported cost-related insulin underuse. Patients with cost-related underuse had lower income levels, variable drug coverage and employment (Figure), and 3-fold higher odds of HbA1c >9% (p = 0.03) than patients who did not report underuse.One in four patients at our urban diabetes center reported cost-related insulin underuse, and this was associated with poor glycemic control. These results highlight an urgent need to address high insulin prices in the U.S.