Comparison of costs among patients with type 2 diabetes treated with exenatide or sitagliptin therapy

Exenatide (ByettaA (R), Amylin Pharmaceuticals Inc., CA, USA) and sitagliptin (JanuviaA (R), Merck & Co, NJ, USA) are two antidiabetic agents recently approved by the US Food and Drug Administration. The purpose of this analysis was to compare costs among patients with type 2 diabetes (T2D) treated with either of these agents. Data with dates of service from September 1, 2005 through August 31, 2007, were obtained from a large US retrospective claims database. Intent-to-treat cohorts of adults diagnosed with T2D who began taking either exenatide (n=1885) or sitagliptin (n=2482) and did not use the alternate medication in the 6-month follow-up period were created. Six-month total medical costs were estimated using stepwise multivariate regressions. Six-month total diabetes-related medical costs, a component of total medical costs, were also estimated using stepwise multivariate regressions. In addition, other cost components were examined using either stepwise multivariate regressions or a two-part model that controlled for the probability of using the medical 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, comorbidities, and timing of treatment initiation. Exenatide was associated with lower total 6-month direct medical costs ($9340 vs. $9995; P < 0.0001), despite some component costs being slightly higher with exenatide: diabetes-related drug costs ($1765 vs. $1743; P=0.0062), diabetes-related medical costs ($4142 vs. $4002; P < 0.0001), and emergency room costs ($43 vs. $29; P=0.0388). Exenatide was associated with lower outpatient costs ($4498 vs. $5942; P < 0.0001). Compared with the use of sitagliptin, exenatide was associated with lower total medical costs (difference of $655) despite higher total diabetes-related costs (difference of $140). As a result, there appears to be overall cost savings associated with the use of exenatide relative to sitagliptin.