Shortly after new antipsychotic drugs came on the market in the late 1990s, the Food and Drug Administration started to worry that they might trigger diabetes in some patients.

So in 2000, the FDA asked AstraZeneca P.L.C. and other pharmaceutical companies to share data on cases of new-onset diabetes and related illnesses in patients taking the drugs. London-based AstraZeneca, which has U.S. headquarters in Wilmington, told the FDA that patients and doctors had reported 12 new cases of diabetes and five cases of related illnesses among the 623,000 who had taken its antipsychotic drug Seroquel.

But internally, the company had reported the number as 27 cases of diabetes and two of hyperglycemia, according to court documents released late Thursday.

The documents surfaced in lawsuits filed in Orlando, Fla., by patients who say taking Seroquel caused their diabetes. Last month, the FDA required AstraZeneca to make information about Seroquel and weight gain, a risk factor in diabetes, more prominent on the drug's label.

Thursday's filing says that in a 2008 deposition, AstraZeneca's medical director, Wayne Geller, explained the difference between the 12 and 27 cases by saying the company had given the FDA only what it requested.

AstraZeneca spokesman Tony Jewell said the same thing yesterday.

"AstraZeneca's 2000 submission provided all of the information that the FDA specifically requested," Jewell said. "AstraZeneca reported the cases of new-onset diabetes-related events, as requested by the FDA."

In its 2000 response to the agency, AstraZeneca said it was "unlikely" that taking Seroquel led to diabetes.

The FDA said it could not comment. Company e-mail messages show that Geller in 2001 called the 27 cases "fairly sizeable." In a deposition last year, Geller said he no longer agreed with that statement. He said he had made it before he knew how many patients had taken Seroquel.

Robert Cowan, the lawyer who wrote the document for plaintiff firm Bailey, Perrin & Bailey in Houston, said AstraZeneca should have reported the larger number.

"It means that AstraZeneca was underreporting adverse events," he said.

Thursday's filing was the latest in a series of documents unsealed in the Florida cases. Documents released last week contained AstraZeneca e-mail in which employees discussed "buried" studies showing connections between Seroquel and weight gain.

AstraZeneca faces personal-injury claims from about 15,000 people who took Seroquel and say it caused diabetes. A judge dismissed the first two cases, saying the patients had failed to show Seroquel caused their diabetes; the other cases are pending.

Contact staff writer Miriam Hill

at 215-854-5520 or hillmb@phillynews.com.