A comparison of costs among patients with type 2 diabetes mellitus who initiated therapy with exenatide or insulin glargine

Abstract

Exenatide (Byetta) and insulin glargine (Lantus) are antidiabetic agents that are typically used after lack of response to an oral antidiabetic agent(s). Although previous research has examined the impact of these medications on glycaemic control, there is little information about the relative costs associated with the medications. To compare costs among patients with type 2 diabetes mellitus treated with exenatide or insulin glargine from a US third-party payer perspective. Data from a large, national administrative claims database were used in this study. The intent-to-treat (ITT) cohort included adults who were diagnosed with type 2 diabetes and initiated therapy with either exenatide (n = 4090) or insulin glargine (n = 1660). In addition, included patients were required to have no diagnoses of type 1 diabetes, to have received at least two prescriptions for an oral antidiabetic agent in the 6 months prior to first use of either exenatide or insulin glargine and to have continuous insurance coverage from 6 months before, to 12 months after, initiation on ITT medication. Annual total medical costs and total diabetes-related medical costs, in $US, year 2007 values, were estimated using stepwise multivariate regressions. Major cost components were also examined using either stepwise multivariate regressions or a two-part model that controlled for the probability of using the service. Smearing estimates were used to transform estimated log costs into costs. The analysis controlled for the potential impact of patient demographics, general health, prior resource use, co-morbidities and complications, and timing of treatment initiation. Compared with insulin glargine, initiation of exenatide was associated with significantly lower total direct medical costs ($US19,293 vs $US23,782; p < 0.0001), inpatient costs ($US4121 vs $US7532; p < 0.0001), outpatient costs ($US9501 vs $US12,885; p < 0.0001), emergency department (ED) costs ($US82 vs $US131; p < 0.0001), total diabetes-related medical costs ($US7833 vs $US8536; p < 0.0001), diabetes-related inpatient costs ($US2172 vs $US3538; p < 0.0001) and diabetes-related outpatient costs ($US2739 vs $US3249; p < 0.0001). Initiation of exenatide was associated with significantly higher total overall drug costs ($US6885 vs $US5936; p < 0.0001) and diabetes-related drug costs ($US3160 vs $US2422; p < 0.0001). Compared with the use of insulin glargine, use of exenatide was associated with significantly lower annual total direct medical costs and significantly lower total diabetes-related medical costs, despite higher total drug costs and higher diabetes-related drug costs. In addition, exenatide was associated with significantly lower total inpatient, outpatient, ED, and diabetes-related inpatient and outpatient costs.