12-OR: Trends in Total and Out-of-Pocket Payment on a Yearly Insulin Supply among Private Health Insured U.S. Adults with Diabetes from 2003 to 2016

High spending, especially out-of-pocket (OOP) payment on insulin, could lead individuals with diabetes to skip or ration doses and worsen future health outcomes. We examined the trends in total and OPP payment on a yearly supply of insulin by type from 2003 to 2016. Using the 2003-2016 MarketScan claims database, we analyzed 1,703,343 adults with diabetes who were continuously enrolled in fee-for-service health plans. Insulin was grouped into 6 types (human insulin, Glargine, Lispro, Aspart, Detemir and Glulisine) using National Drug Code. Total and OOP payment for each drug type were modelled at a 30-day supply level, and later multiplied by 12 to obtain yearly estimates. A joinpoint regression was used to identify inflection points and to estimate trends in each defined segment. Payments were standardized to 2016 USD. The total payment for insulin increased at annual rate of $162 per year from 2003 ($1982) to 2012 ($3686), followed by more than a 3-fold increase in the annual rate of increase to $708 per year between 2013 ($4392) and 2016 ($6250). By type, the annual rate of increases ranged from $64 (2%) for Glulisine to $133 (6%) for Glargine before the inflection point and raised to a range from $631 (16%) for Glargine to $1246 (26%) for Glulisine after the inflection point. OPP payment on a yearly supply of insulin decreased by $6 per year (-1.5%) between 2003 ($390) and 2009 ($384) followed by a 3% ($12) per year increase between 2010 ($405) and 2016 ($451). The annual rate of changes ranged from -$72 (14.8%) for Detemir to -$31 (-6%) for Glulisine before the inflection point and varied from $8 (2%) for Aspart to $41 (7.6%) for Glulisine after the inflection point. Total payment on a yearly supply of insulin had been increasing since 2003 but accelerated after 2011. The OPP payment reversed its trends from a decrease to an increase. But the much smaller increase in OPP payment than the total payment after 2011 suggests that payers bore most of the insulin spending increase.