Background: People with diabetes are at an increased risk of developing numerous complications, resulting in increased health care expenditures, economic burden, and higher mortality. For patients using an insulin pump or multiple insulin injections, self-monitoring of blood glucose (SMBG) is recognized as a core component of effective diabetes self-management. However, little is known about the real-world frequency and true costs associated with SMBG as a percentage of an insulin regimen in the United States.
Objective: To evaluate SMBG frequency, SMBG-related costs (including blood glucose test strips and testing supplies), and insulin therapy costs among insulin-dependent patients with diabetes and at least 1 pharmacy claim for blood glucose testing strips during a 12-month follow-up period.
Methods: A retrospective database analysis was conducted using the IMS LifeLink Health Plan Claims database to capture the frequency and costs associated with SMBG in relation to a specific insulin regimen, and SMBG expenditure compared with other treatment costs. The study employed a retrospective cohort analysis of patients with 2 or more claims for insulin between January 1, 2007, and June 30, 2009, with the first such claim representing the index date. All patients were required to have 6 months of pre-index continuous enrollment (pre-index period) and 12 months of post-index continuous enrollment (follow-up period). Patients were also required to have a diagnosis of diabetes in the pre-index period and to have no gaps of more than 90 days between consecutive insulin claims during the 360-day follow-up period. Patients without at least 1 pharmacy claim for blood glucose testing strips during the 12-month follow-up period and patients with pharmacy claims with extreme values (greater than 1,500 strips) were excluded. Depending on the insulin types used within the 30 days immediately following their index date, patients were subcategorized into 1 of 4 insulin regimen groups (basal, bolus, premixed, or basal-bolus). Patients' frequency of blood glucose testing was measured throughout their 12-month post-index follow-up period through analysis of clinical codes found on pharmacy claims. Quantity supplied fields on pharmacy claims were used to calculate total tests utilized over the follow-up period (e.g., 50 test strips dispensed=50 tests assumed). Insulin-related costs were also evaluated for the 12-month follow-up period.
Results: Among an initial sample of 373,946 patients with at least 2 claims for insulin between January 1, 2007, and June 30, 2009, 45,555 patients (12.2%) formed the final overall cohort who met the inclusion and exclusion criteria. SMBG-related pharmacy costs accounted for 27% of the insulin-and SMBG-related treatment costs for insulin users with an average $772 per patient in prescription testing strips and supplies versus $2,078 for insulin prescriptions and supplies. With an overall mean utilization for pharmacy-based SMBG testing of 764.3 strips per year, the average cost per testing strip was $0.98. Annual SMBG costs were 24.5% of total insulin and SMBG-related pharmacy costs for the basal insulin group compared with 35.8% for bolus, 21.0% for premixed, and 26.4% for basal-bolus.
Conclusion: For insulin users with at least 1 pharmacy claim for glucose test strips, SMBG-related costs accounted for about one-fourth of total insulin and SMBG-related pharmacy costs.