WASHINGTON -- Pfizer (PFE - Get Report) says its studies in the U.S. and the U.K. show more thanhalf of patients suffering from the most common form of diabetes delay taking insulin injections, including some who hold off for more than four years.

The drugmaker released the studies Monday as it tries to put some numbers behind its claim that the inhaled insulin Exubera will meet a receptive market because many diabetics don't want to inject the drug. The report was issued a few days after Pfizer revealed it would begin marketing Exubera in the U.S. in July.

The Food and Drug Administration approved the drug in January, but Pfizer decided to conduct an education campaign for doctors and patients before making Exubera available. The company still hasn't announced a price.

Exubera is a dry powdered form of insulin that patients inhale through themouth with a device developed by Nektar Therapeutics ( NKTR - Get Report). The drug is approved for both Type 1 and Type 2 diabetes. In the former, which accounts for about 5% of cases, the body can't produce insulin to convert sugar into fuel. In the latter, the body doesn't make enough insulin or the cells don't do a good job of using the insulin.

The studies "demonstrate that people put their health at risk and suffer devastating complications to avoid injecting insulin," says Dr. Jack Watters, vice president for medical affairs at Pfizer, in a prepared statement. "We believe that Exubera will improve patients' acceptance of insulin and thereby reduce the risk for serious complications in the future."

One Pfizer study looked at 2,501 patient records from more than 100 general practices in the U.K. over 17 years. Half the patients delayed starting insulin for at least four years after the blood-sugar control pills stopped being effective, according to the study. The results were released at the annual scientific session of the American Diabetes Association. Those patients delayed taking insulin even if they had already suffered complications from diabetes.

A similar study in the U.S. examined 4,367 patient records over eight years from the Portland, Ore., unit of the Kaiser Permanente health system. "Only half of the patients taking two diabetes pills achieved targeted control of blood sugar levels, and half the patients delayed the start of insulin for four years," Pfizer says.

Pfizer's release of the studies is designed not only as a marketing tool but also as a challenge to British health care regulators. Although the European Union has approved Exubera, and the drug is now available in Germany and Ireland, the U.K. is undecided on reimbursement. The British agency that makes recommendations to the National Health Service issued a preliminary report in April recommending against reimbursement.

The studies "counter the basis for the preliminary opinion" by the British agency, Pfizer says. The opinion "was based in part on the belief that injected insulin was not a concern for the majority of people with diabetes."

The agency's preliminary report will be reviewed, and a final decision is expected in the fall. Pfizer has sent the results of the patient satisfaction reports to the agency and continues to press its case.

In April, the U.K. agency expressed concerns about the survey methods it had received from Pfizer. In each of five studies, respondents favored inhaled insulin over injectable insulin.

The preliminary report says the government shouldn't pay for inhaled insulin"except in the context of clinical studies designed to evaluate the clinical and cost-effectiveness of inhaled insulin" vs. injectable insulin in people whose blood-sugar levels aren't controlled with existing medications. The agency says it didn't receive any cost-effectiveness studies.

The agency recommended against inhaled insulin "for the diabetic population as a whole." It says Exubera "should not be recommended for patients whose blood glucose levels remained uncontrolled because of a very strong aversion to insulin injections," adding that "there is currently insufficient evidence of clinical effectiveness in this patient group."

Although Pfizer hasn't announced a price for Exubera, some analysts say it will definitely cost more than injectable insulin. James Kelly of Goldman Sachs told clients in a report issued before the ADA convention that Exubera may cost $4 a day compared with the $3-a-day price for injectable insulin. In another report issued before the convention, Andrew Forman of WR Hambrecht speculated that Exubera would cost $4.40 a day.

The big questions for Pfizer and Nektar are how much extra will people pay and how much more will insurers pay for a product whose blood-sugar control ability is similar to injectable insulin?

"For some patients, doctors and budget holders, the issue of drug costs, cost-effectiveness and uncertainty regarding potential long-term adverse effects ... will outweigh the perceived benefits of ease of administration," said an editorial in the British Medical Journal last month by two medical professors from the University of Virginia. One of the authors has received consulting fees, speaking fees and a research grant from Pfizer.

However, the authors said that patients "who are distressed by frequent injections may be able to improve their blood sugar control substantially and avoid complications with this new product."