78% Lower Overdose Risk: The Volkow Study That Shocked Addiction Medicine

The Study

Published in JAMA Network Open in September 2024, this study came from a powerhouse team: William Wang and Rong Xu at Case Western Reserve University, alongside Nora D. Volkow, MD — the longtime director of the National Institute on Drug Abuse (NIDA) and one of the most influential figures in addiction science.

The researchers used a method called target trial emulation, analyzing de-identified electronic health records from over 33,000 patients who had both Type 2 diabetes and opioid use disorder. They compared patients prescribed semaglutide against those prescribed other antidiabetic medications — insulin, metformin, DPP-4 inhibitors, SGLT2 inhibitors, sulfonylureas, thiazolidinediones, and even other GLP-1 receptor agonists like liraglutide and dulaglutide.

The question was straightforward: did semaglutide users experience fewer opioid overdoses over a one-year follow-up period?

The Numbers

The range of 42-68% lower risk depending on the comparison group represents a massive effect size for an observational study. And the fact that semaglutide outperformed other GLP-1 receptor agonists — not just non-GLP-1 diabetes drugs — suggests something specific about semaglutide's pharmacology may be at work.

Why Semaglutide Specifically?

This is one of the most intriguing aspects of the data. Older GLP-1 receptor agonists like exenatide and liraglutide showed some anti-addiction properties in preclinical studies, but results in humans were mixed. An early clinical trial of exenatide for alcohol use disorder was inconclusive.

Semaglutide appears to be different, and the leading hypothesis centers on brain penetration. GLP-1 receptors are expressed throughout the brain's reward circuitry — the ventral tegmental area (VTA), nucleus accumbens, amygdala, and prefrontal cortex. These are the exact regions hijacked by addictive substances. But to modulate those receptors, a drug needs to actually reach them.

Semaglutide has superior ability to access the central nervous system compared to first-generation GLP-1 agonists. This may explain why it produces stronger effects on craving and reward-seeking behavior — not just for food, but across multiple substances including opioids, alcohol, and nicotine.

The Confirmation: 1.3 Million Records

The Wang/Volkow findings were reinforced by a separate large-scale study published in Addiction in early 2025. Led by Fares Qeadan at Loyola University Chicago, this analysis examined electronic health records from 136 U.S. health systems covering over 1.3 million patients.

Among 503,747 patients with a history of opioid use disorder, those prescribed any GLP-1 receptor agonist demonstrated a 40% lower rate of opioid overdose events over a two-year follow-up period, even when stratified by comorbidities. The finding was consistent regardless of whether patients also had Type 2 diabetes or obesity.

That consistency across comorbidity subgroups matters. It suggests the protective effect isn't just a side effect of better metabolic health — it's something the drug is doing directly to reward and craving pathways.

What's Coming Next: The Penn State Trial

While the observational data is compelling, the field needs randomized controlled trials. The most significant one currently underway is led by Patricia Grigson and colleagues at Penn State, with a protocol published in mid-2025.

This trial will enroll 200 participants with treatment-refractory opioid use disorder who are already enrolled in medication-assisted treatment programs (100 on buprenorphine, 100 on methadone). Half will receive semaglutide, half placebo. The primary outcome: abstinence from illicit and non-prescribed opioids, measured by urine toxicology screens.

This is the first controlled clinical trial designed to determine whether a GLP-1 receptor agonist can actually increase abstinence rates in OUD patients. If positive, it would represent a paradigm shift — a non-opioid pharmacological intervention for opioid addiction.

The Scale of the Problem

Context matters here. Roughly 65,000 Americans died from fentanyl overdoses in the most recent 12-month reporting period. Total opioid-related deaths remain above 80,000 annually. Existing medications for OUD — methadone, buprenorphine, naltrexone — are effective but insufficient. Many patients are treatment-refractory, meaning they continue to use despite being enrolled in medication-assisted treatment programs.

If semaglutide can add even an incremental layer of protection against overdose and craving in this population, the public health implications would be enormous. A 40-68% reduction in overdose risk, if confirmed by RCTs, would represent one of the most significant advances in OUD treatment in decades.