Comparative effectiveness and costs of insulin pump therapy for diabetes.

OBJECTIVES: Continuous subcutaneous insulin infusion (CSII), or "insulin pump" therapy, is an alternative to multiple daily insulin injections (MDII) for management of diabetes. This study evaluates patterns of healthcare utilization, costs, and blood glucose control for patients with diabetes who initiate CSII.

STUDY DESIGN: Pre-post with propensity-matched comparison design involving commercially insured US adults (aged 18-64 years) with insulin-requiring diabetes who transitioned from MDII to CSII between July 1, 2009, and June 30, 2012 ("CSII initiators"; n = 2539), or who continued using MDI (n = 2539).

METHODS: Medical claims and laboratory results files obtained from a large US-wide health payer were used to construct direct medical expenditures, hospital use, healthcare encounters for hypoglycemia, and mean concentration of glycated hemoglobin (A1C). We fit difference-in-differences regression models to compare healthcare expenditures for 3 years following the switch to CSII. Stratified analyses were performed for prespecified patient subgroups.

RESULTS: Over 3 years, mean per-person total healthcare expenditures were $1714 (95% confidence interval [CI], $1184-$2244) higher per quarter for CSII initiators compared with matched MDII patients (total mean 3-year difference of $20,565). Compared with matched controls, mean A1C concentrations became lower for CSII initiators by 0.46% in year 2 (P = .0003) and by 0.32% in year 3 (P = .047). CSII initiators also had a higher rate of hypoglycemia encounters in year 1 (P = .002).

CONCLUSIONS: For adults with insulin-requiring diabetes, transitioning from MDII to CSII was associated with modest improvements in A1C but more hypoglycemia encounters and increased healthcare expenditures, without significant improvement in other potentially offsetting areas of healthcare consumption.