Treatment Patterns and Characteristics of Individuals Initiating High-Dose Insulin for Type 2 Diabetes Mellitus

BACKGROUND: Few studies have examined patient characteristics and treatment patterns of high-dose insulin therapy (> 200 units/day) among patients with type 2 diabetes mellitus (T2DM). OBJECTIVE: To understand patient characteristics, dosing, adherence, and persistence related to high-dose insulin therapy. METHODS: This was a retrospective observational study that used administrative claims from a large national health plan. Patients were identified who had been diagnosed with T2DM and who were aged 18-89 years, enrolled in a commercial or Medicare Advantage Prescription Drug plan, newly initiated on a total daily dose (TDD) > 200 units of insulin between January 2011 and August 2015. Patients were required to be enrolled 6 months before and 12 months after the index date. Patients were categorized to Regimen-100 if treated with U-100 insulin only or Regimen-500 if treated with U-500R with or without U-100. Baseline demographic and clinical characteristics were evaluated. An adjustment factor for the days supply was calculated as the ratio of median time between insulin claims, and median pharmacy reported days supply for each insulin prescription. Adjusted days supply, quantity, and concentration were used to calculate TDD for each quarter after the index date. Adherence was measured as the proportion of days covered (PDC) for each regimen. Persistence was measured in 2 ways: the percentage of patients remaining on index medications in each quarter and the proportion of patients who maintained TDD > 200 units during all 4 quarters of the 12-month post-index period. RESULTS: We identified 2,339 patients newly titrated up to TDD > 200 units on either Regimen-100 (2,062, 88.2%) or Regimen-500 (277, 11.8%). Patients on Regimen-500 were slightly younger with higher prevalence of comorbidities. The mean TDD (SD) for Regimen-100 decreased from 228.6 (36.0) units during the first quarter to 194.2 (181.4) units during the last quarter. The mean TDD (SD) for Regimen-500 increased from 294.2 (102.2) units in the first quarter to 304.8 (281.6) units in last quarter. The average adherence to the high-dose insulin regimen was 68.2% (30.7; median 72.6%) for the Regimen-100 cohort and 75.5% (27.0; median 85.2%) for the Regimen-500 cohort. In the Regimen-100 and Regimen-500 cohorts, 45.3% and 55.2% had a PDC ≥ 80%, respectively. Only 23.0% and 51.6% of patients maintained TDD > 200 units for the Regimen-100 and Regimen-500 cohorts, respectively, throughout the 4 quarters after the index date. CONCLUSIONS: We observed that many patients did not maintain high-dose insulin use over time, especially those on standard U-100 insulin only. This dosing pattern appears to reflect the differences in patient characteristics, insulin needs, and adherence/persistence behavior between those on Regimen-100 and those on Regimen-500.