Changes in diabetes prescription patterns following Affordable Care Act Medicaid expansion

Most patients with diabetes mellitus are prescribed medications to control their blood glucose. The implementation of the Affordable Care Act (ACA) led to improved access to healthcare for patients with diabetes. However, impact of the ACA on prescribing trends by diabetes drug category is less clear. This study aims to assess if long-acting insulin and novel agents were prescribed more frequently following the ACA in states that expanded Medicaid compared with non-expansion states.

In this analysis of a natural experiment, prescriptions reimbursed by Medicaid (US public insurance) for long-acting insulins, metformin, and novel agent medications (DPP4 inhibitors, sodium/glucose cotransporter 2 inhibitor antagonists, and glucagon-like peptide-1 receptor agonists) from 2012 to 2017 were obtained from public records. For each medication category, we performed difference-in-differences (DID) analysis modeling change in rate level from pre-ACA to post-ACA in Medicaid expansion states relative to Medicaid non-expansion states.

Expansion and non-expansion states saw a decline in both metformin and long-acting insulin prescriptions per 100 enrollees from pre-ACA to post-ACA. These decreases were larger in non-expansion states relative to expansion states (metformin: absolute DID = +0.33, 95% CI=0.323 to 0.344) and long-acting insulin (absolute DID: +0.11; 95% CI=0.098 to 0.113). Novel agent prescriptions in expansion states (+0.08 per 100 enrollees) saw a higher absolute increase per 100 Medicaid enrollees than in non-expansion states (absolute DID= +0.08, 95% CI=0.079 to 0.086).

There was a greater absolute increase for prescriptions of novel agents in expansion states relative to non-expansion states after accounting for number of enrollees. Reducing administrative barriers and improving the ability of providers to prescribe such newer therapies will be critical for caring for patients with diabetes-particularly in Medicaid non-expansion states.