GLP-1 Manufacturers Argue Gastroparesis Lawsuits Should Require Contemporaneous Diagnostic Testing

Plaintiffs’ experts have maintained that there are multiple reliable ways to diagnose gastroparesis, which should not require specific testing results that doctors often do not order when the injury first surfaces.

Eli Lilly, the manufacturer of the diabetes drug Mounjaro and the weight loss drug Zepbound, is asking the U.S. District Judge presiding over all GLP-1 stomach paralysis lawsuits to put stringent requirements in place for establishing that plaintiffs have a gastroparesis diagnosis after using the medications.

Mounjaro and Zepbound are part of the same new class of drugs as blockbuster treatments Ozempic and Wegovy, known as glucagon-like peptide-1 (GLP-1) receptor agonists, which are widely used for the treatment of type 2 diabetes and for weight loss. 

Amid growing popularity of the drugs in recent years, both Eli Lilly and other GLP-1 manufacturers now face more than 1,500 Ozempic lawsuits, Wegovy lawsuits, Mounjaro lawsuits and other claims brought by former users of the medications, who indicate that they developed a severe form of stomach paralysis, known as gastroparesis.

Each of the lawsuits raises similar allegations, indicating that the drug makers knew or should have known about the potential gastroparesis side effects, but placed a desire for profits above consumer safety, by withholding critical warnings and safety information from consumers and the medical community.

Given common questions of fact and law raised in complaints brought throughout the federal court system, all GLP-1 lawsuits have been centralized as part of a multidistrict litigation (MDL) in the Eastern District of Pennsylvania, where they are currently being overseen by U.S. District Judge Karen Marston.

To effectively manage the rapidly growing litigation, Judge Marston established a pretrial process that directed the parties to focus early discovery and motions practice on resolving a number of “cross-cutting” issues in the GLP-1 lawsuits, including whether plaintiffs should be required to present specific diagnostic testing evidence to substantiate their injuries, whether the claims are preempted by federal law, and whether there is sufficient general causation evidence linking gastrointestinal injuries to GLP-1 drugs, which is expected to address whether the failure to warn claims survive.

In a motion (PDF) filed on March 5, Eli Lilly called for Judge Marston to issue an order requiring contemporaneous objective testing as the only means by which a gastroparesis injury can be diagnosed. Although plaintiffs’ experts have maintained that there is more than one reliable way to diagnose the condition, Eli Lilly wants the judge to exclude those opinions from being presented at trial.

“The overwhelming majority—more than 80 percent—of Plaintiffs in this MDL allege gastroparesis as an injury. One of the defining features of gastroparesis is delayed gastric emptying, accompanied by gastrointestinal symptoms like early fullness after meals, abdominal pain, nausea, vomiting, belching, and bloating,” the motion states. “These symptoms are non-specific; they overlap with many other, more common conditions; and they do not alone reliably indicate delayed gastric emptying or gastroparesis.”

The manufacturer claims that gastroparesis is misdiagnosed as much as 80% of the time without objective testing. Plaintiffs have not yet responded to the motion, and it is unclear how many claims would be affected by the motion, if Judge Marston approves it.

March 2025 GLP-1 Lawsuits Update

The lawyers involved in the litigation are scheduled to meet with Judge Marston for a status conference tomorrow, on March 18.

According to an agenda (PDF) submitted by the parties last week, the pending motion to require contemporaneous diagnostic testing in gastroparesis lawsuits is not expected to be addressed by the court at the conference. However, the parties have asked Judge Marston to review deposition protocols, a coordination order and a short form complaint that future plaintiffs can use to file their lawsuits.

After the “cross-cutting” issues are resolved, and if the lawsuits are cleared to move forward, Judge Marston is expected to schedule a series of early bellwether trials, which will test how juries may respond to certain evidence and testimony likely to be repeated throughout the litigation.

Due to the time needed to resolve the “cross-cutting” issues and then select and prepare a group of early cases for trial, the first GLP-1 lawsuits are unlikely to go before federal juries until at least 2027.

While the outcomes of these early test cases will not be binding on other claims, they will be closely watched and may help the parties negotiate GLP-1 settlements to resolve large numbers of lawsuits in the future.