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Adherence to GLP-1 Therapy Yields Better A1c Outcomes, Higher Costs

Adherent patients were more likely to achieve at least a 1.0% drop in A1c; half achieved the ADA-prescribed goal of <7%. Higher cost was not a surprise.

Patients with type 2 diabetes (T2DM) who were able to consistently adhere to their treatment with the glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide achieved improved HbA1c (A1c) outcomes but had higher total healthcare costs compared with counterparts who were non-adherent, the results of a recent study showed.  

“The fact that those classified as adherent and/or persistent had higher pharmacy costs is not unexpected, given that these cohorts include patients who consistently adhered to their medication and continued to fill their prescriptions as directed, while those in the nonadherent and nonpersistent cohorts did not,” wrote Erin K. Buysman, MS, associate director at Optum, a health services organization, and colleagues in Advanced Therapeutics. “It is likely that adherent and persistent patients experienced better A1c outcomes as a direct result of their consistent medication use, demonstrating that the additional cost comes with improved clinical outcomes.”

According to the study, adherence to diabetes medications is generally considered to be poor, but previous research has focused on adherence to oral agents. In this study, the researchers examined adherence and persistence to injectable once-daily liraglutide and its effects on glycemic control and medical costs.

The study included administrative healthcare claims data from July 2009 to September 2013 for 1321 patients aged 18 years or older with T2DM. Adherence was defined as a proportion of days covered greater than 80%. Persistence to liraglutide was defined by the continuation or discontinuation of the medication as measured via the days’ supply reported on pharmacy claims. A nonpersistent patient was any patient with a gap in therapy of greater than 90 days.

The average proportion of days covered was 59%. About one-third of patients (34%) were classified as adherent to their medication with a proportion of days covered of 80% or greater. Sixty percent of patients were considered “persistent” for the entire 365-day study follow-up. Those patients found to be adherent had a lower baseline A1c compared with nonadherent patients (8.08% vs 8.29%; P=.033).

Parameters of glycemic control were improved in patients who were adherent to or persistent with liraglutide. Patients who were adherent had a mean A1c reduction of 0.81% compared with 0.42% in nonadherent patients (P<.001). Persistent patients also had greater reductions in A1c compared with nonpersistent patients (0.78% vs 0.21%; P<.001).

Fifty percent of patients classified as adherent achieved an A1c goal of less than 7% compared with 39% of patients who were non-adherent (P<.001).

After multivariate adjustment, the researchers found that “adherent patients had a significantly larger decrease in A1c and were more likely to achieve at least a 1.0% reduction in A1c than their nonadherent counterparts.”

The overall mean healthcare cost per patient was $8186. Although lower utilization of the emergency room (ER) and inpatient services among adherent patients resulted in lower unadjusted diabetes-related medical costs, adherent patients had significantly greater pharmacy costs than nonadherent patients ($6338 vs. $3568; P<.001).

“When medical costs (which include costs for ambulatory visits, ER services, IP services, and other services) and pharmacy costs were summed, the result was a higher total healthcare cost among adherent patients ($9081 vs $7717, P =0.028), on average,” the researchers wrote.


Funding for this study was provided by Novo Nordisk, Inc., Plainsboro, New Jersey, USA.


Buysman EK, Liu F, Hammer M, Langer J. Impact of medication adherence and persistence on clinical and economic outcomes in patients with type 2 diabetes treated with liraglutide: a retrospective cohort study. Adv Ther. Epub 2015 Apr 2.