A committee of 178 doctors specializing in treating diabetes was rebuffed yesterday by the U.S. Court of Appeals here in an attempt to examine "raw data" used in a controversial, federally-financed $7.3 million study of the disease.

The Boston-based medical group, known as the Committee on the Care of the Diabetes, long has sought access to the basic research data in what the appeals court termed an attempt by the doctors to challenge the study's validity.

The Court of Appeals, in a 2-to-1 ruling, held that the physicians did not have the right to obtain the raw data under the Freedom of Information Act because these data were in the possession of universities and private researchers who carried out their studies under U.S. grants. The data are not in the hands of the federal government itself the court noted.

Michael X. Morrell, one of the lawyers who has represented the physician's committee, said the group would either seek a re-hearing of its appeal or would appeal yesterday's ruling to the U.S. Supreme Court.

At issue is a study conducted at 12 university medical centers in which more than 1,000 diabetics were treated for periods of 9 to 11 years. The study largely completed in 1970, was financed by the National Institutes of Health.

Among the study's controversial findings was that there is no evidence that use of insulin or other substances designed to lower blood sugar in adults with mild diabetes will prevent progressive damage to blood vessels - the main cause of disabilities and death among diabetics.

A U.S. Food and Drug Administration spokesman said yesterday that the FDA is audating the NIH-financed diabetes study to determine whether its scientific conclusions were accurate. The audit will be completed by the end of this month, the spokesman said.