Estimated Changes in Insulin Prices and Discounts After Entry of New Insulin Products, 2012-2019

Abstract

Importance: Despite the political salience of insulin prices, no study to date has quantified trends in insulin prices that account for manufacturer discounts (net prices).

Objective: To describe trends in insulin list prices and net prices faced by payers from 2012 to 2019 and estimate changes in net prices after the 2015 to 2017 entry of new insulin products.

Design, setting, and participants: This longitudinal study included an analysis of Medicare, Medicaid, and SSR Health drug pricing data from January 1, 2012, to December 31, 2019. Data analyses were performed from June 1, 2022, to October 31, 2022.

Exposures: US sales of insulin products.

Main outcomes and measures: Net prices faced by payers were estimated for insulin products as list prices minus manufacturer discounts negotiated in commercial and Medicare Part D markets (ie, commercial discounts). Trends in net prices were evaluated before and after the entry of new insulin products.

Results: Net prices of long-acting insulin products increased at an annual rate of 23.6% from 2012 to 2014 but decreased at an annual rate of 8.3% after the introduction of insulin glargine (Toujeo and Basaglar) and degludec (Tresiba) in 2015. Net prices of short-acting insulin increased at an annual rate of 5.6% from 2012 to 2017 but then decreased from 2018 to 2019 after the introduction of insulin aspart (Fiasp) and lispro (Admelog). For human insulin products, which did not experience entry of new products, net prices increased at an annual rate of 9.2% from 2012 to 2019. From 2012 to 2019, commercial discounts increased from 22.7% to 64.8% for long-acting insulin products, from 37.9% to 66.1% for short-acting insulin products, and from 54.9% to 63.1% for human insulin products.

Conclusions and relevance: In this longitudinal study of US insulin products, results suggest that insulin prices substantially increased from 2012 to 2015, even after accounting for discounts. The introduction of new insulin products was followed by substantial discounting practices that lowered net prices faced by payers.

Figure 1.. Trends in List Prices, Net Prices, and Discounts for Long-Acting Insulin Analogues

List prices were estimated as mean reimbursement rates in Medicare Part D per 100 insulin units. Net prices were estimated as the difference between list prices and commercial discounts and represent the prices faced by Part D and private plans after rebates. The insulin glargine Toujeo was approved in February 2015, insulin degludec (Tresiba) in September 2015, and the insulin glargine Basaglar in December 2015. As explained in the Methods, prices and discounts of new products are not reported for the first year after market entry (drugs approved in the first half of a calendar year) or 2 years after market entry (drugs approved in the second half of a calendar year) to mitigate how inventory variation may have affected the data, which is why data for Toujeo are first reported in 2016 and data for insulin degludec and Basaglar are first reported in 2017. Outcomes are expressed per 100 insulin units. The dashed line indicates approval for Toujeo, insulin degludec, and Basaglar.

Figure 2.. Trends in List Prices, Net Prices, and Discounts for Short-Acting Insulin Analogues

List prices were estimated as mean reimbursement rates in Medicare Part D per 100 insulin units. Net prices were estimated as the difference between list prices and discounts and represent the prices faced by Part D and private plans after rebates. Fiasp was approved in September 2017 and insulin lispro (Admelog) in December 2017. As explained in the Methods, prices and discounts of new products are not reported for the first year after market entry (drugs approved in the first half of a calendar year) or 2 years after market entry (drugs approved in the second half of a calendar year) to mitigate how inventory variation may have affected the data, which is why data for Fiasp and insulin lispro are first reported in 2019. Outcomes are expressed per 100 insulin units. The dashed line indicates approval for Fiasp and insulin lispro.

Figure 3.. Trends in List Prices, Net Prices, and Discounts for Human Insulin Products

List prices were estimated as mean reimbursement rates in Medicare Part D per 100 insulin units. Net prices were estimated as the difference between list prices and discounts and represent the prices faced by Part D and private plans after rebates. Outcomes are expressed per 100 insulin units.