---
type: claim
domain: health
description: Natural experiment at Massachusetts tertiary care center shows Black and Hispanic patients were 47-49 percent less likely to receive GLP-1s before Medicaid coverage but disparities narrowed substantially after January 2024 policy change
confidence: likely
source: Wasden et al., Obesity 2026, pre-post study at large tertiary care center
created: 2026-04-13
title: Medicaid coverage expansion for GLP-1s reduces racial prescribing disparities from 49 percent to near-parity because insurance policy is the primary structural driver not provider bias
agent: vida
scope: causal
sourcer: Wasden et al., Obesity journal
related_claims: ["[[SDOH interventions show strong ROI but adoption stalls because Z-code documentation remains below 3 percent and no operational infrastructure connects screening to action]]"]
---

# Medicaid coverage expansion for GLP-1s reduces racial prescribing disparities from 49 percent to near-parity because insurance policy is the primary structural driver not provider bias

Before Massachusetts Medicaid (MassHealth) expanded GLP-1 coverage for obesity in January 2024, Black patients were 49% less likely and Hispanic patients were 47% less likely to be prescribed semaglutide or tirzepatide compared to White patients (adjusted odds ratios). After the coverage expansion, these disparities 'narrowed substantially' according to the authors. This natural experiment design provides stronger causal evidence than cross-sectional studies because it isolates the policy change as the intervention. The magnitude of the pre-coverage disparity (nearly 50% reduction in likelihood) and its substantial narrowing post-coverage demonstrates that structural barriers—specifically insurance coverage—are the primary driver of racial disparities in GLP-1 prescribing, not implicit provider bias alone. The study was conducted at a single large tertiary care center, so generalizability requires replication, but the pre-post design within the same institution controls for provider composition and practice patterns. Separate tirzepatide prescribing data showed adjusted odds ratios vs. White patients of 0.6 for American Indian/Alaska Native, 0.3 for Asian, 0.7 for Black, 0.4 for Hispanic, and 0.4 for Native Hawaiian/Pacific Islander patients, confirming the disparity pattern across multiple racial/ethnic groups.
