Medicare Part D parameters are updated annually so member costs typically do not change significantly from one year to the next. However, as rebates have increased over time, the ratio of member cost sharing to the allowed cost net of rebates, or net drug cost, has increased. This is creating an increasing gap between the gross member share and the net member share of the Part D benefit. This paper explores how member cost sharing has changed over time for Part D non-low income members taking diabetic medications.

This paper was commissioned by The Pharmaceutical Research and Manufacturers of America (PhRMA).