Internal company documents show that Eli Lilly concealed information about side effects of its schizophrenia drug Zyprexa, The New York Times said Saturday.

The Times said it received the documents and e-mails from a lawyer representing patients who have used Zyprexa. They show that the company was warned as early as 1999 that Zyprexa's side effects for many patients included weight gain and an increase in blood sugar, both risk factors for diabetes.

About 2 million people worldwide used Zyprexa last year, spending a total of $4.2 billion. The drug is the company's biggest moneymaker.

In 1999, Dr. Alan Breier, now Lilly's chief medical officer, told more than 20 employees he was setting up an executive committee to study the side effects of olanzapine, the chemical name for Zyprexa.

"Olanzapine-associated weight gain and possible hyperglycemia is a major threat to the long-term success of this critically important molecule," he said in an e-mail.