Costarting sitagliptin with metformin is associated with a lower likelihood of disease progression in newly treated people with type 2 diabetes: a cohort study.

ABSTRACT

AIM: To examine whether early addition of sitagliptin to metformin is associated with a delay in type 2 diabetes progression. METHODS: Administrative health records from Alberta, Canada, for the period April 2008 to March 2015, were used to conduct a retrospective cohort study in new metformin users. People who started sitagliptin on the same day they initiated metformin therapy were compared with those who added sitagliptin later. Insulin initiation served as a surrogate marker for diabetes progression, and multivariable logistic regression models were used to evaluate the association with sitagliptin addition (costart vs later use). A mixed-effects linear regression model was used to examine the effect of timing of sitagliptin addition on HbA1c change over 1 year. RESULTS: The mean (sd) age of the 8764 people who used sitagliptin was 52.1 (11.1) years, 5665 (64.6%) were men, and 1153 (13.2%) started sitagliptin on the same day as metformin. Insulin was added to the therapy of 173 (15.0%) costarters and 1453 (19.1%) later sitagliptin users. The adjusted odds ratio for adding insulin was 0.76 (95% CI 0.64 to 0.90) in favour of costarting sitagliptin. HbA1c levels decreased in both groups 1 year after starting sitagliptin, with costarters having a significantly greater reduction [absolute between-group difference of 0.5% (95% CI 0.3 to 0.7)] compared with later sitagliptin users. CONCLUSION: Costarting drug therapy with sitagliptin and metformin was associated with a lower likelihood of disease progression in people with type 2 diabetes compared with adding sitagliptin later.