All eyes were on television soap opera star Gloria Loring as she described the plight of children with diabetes.

One day soon, the actress told a Senate subcommittee, someone will write a book on how diabetes was cured. And that book, she said, "will be dedicated to you, the members of this committee, who had the vision and patience to ignore what might have been politically expedient and to do what you know in your hearts was right."

Doing what is right, in the view of the Juvenile Diabetes Foundation, which Loring represents, means approving $5.7 billion for the National Institutes of Health, an 11 percent increase over this year's budget. It also means approving $7.5 million for state diabetes control projects and $1.9 million for a model diabetes care program.

Every member of the Senate Appropriations subcommittee on Labor, Health and Human Services and Education is accustomed to these dramatic pleas for help. They sit through weeks of public testimony each spring, listening to poignant pitches for one worthy cause after another. But even these veteran politicians took notice on May 2 when the day's 20th witness took her seat.

"She's such a gorgeous thing, and she was so articulate," Sen. William Proxmire (D-Wis.), the panel's senior Democrat, said after Loring's appearance. Proxmire had been scheduled to take over the hearing from Chairman Lowell P. Weicker Jr. (R-Conn.), but Weicker refused to yield the gavel, staying on to question Loring himself.

It is called the "disease lobby" in the corridors of Congress, and no interest group in town is more effective. For each ailment -- from cancer and cystic fibrosis to arthritis, anemia, asthma and Alzheimer's disease -- there is an organization seeking more funds for research.

Their champion is Weicker, who has secured generous increases for NIH since he took over the subcommittee two years ago. While the Reagan administration has been taking a budget knife to other domestic programs, Weicker helped to boost NIH's funding by 12 percent in 1983 and 13 percent last year.

Weicker has garnered enough support on the panel to push through these large increases with little dissent. Now he is trying to prevent the administration from cutting the number of NIH grants awarded each year from 6,500 to 5,000.

During seven days of public hearings this month as the subcommittee prepared to craft a spending bill, it heard from more than 200 outside witnesses, from universities to labor unions to trade associations. The great majority were trying to ensure that Congress did nothing to stem the flow of research money handed out by the 11 NIH institutes.

Each group had a way to personalize its case. Roberta DeVito, president of the American Brittle Bone Society, highlighted the effects of the rare skeletal disease by wheeling her 9-year-old son, Congie, into the hearing room. She told Weicker of "the joy in knowing that you are working to achieve some answers to this problem."

Laura Bailey, a diabetes victim from Maine, pulled two vials of insulin and a handful of syringes from her pocketbook to show the senators how she prepares her medication three times a day. "I call this my pancreas," she said.

Some painted the panel's task as a sort of patriotic duty. "Gentlemen . . . you are the hope of thousands of chronically ill men, women and children afflicted with fatal liver diseases," said Joyce Willig, Connecticut copresident of the American Liver Foundation.

While some groups trotted out the usual collection of Washington lobbyists, others relied on respected authority figures -- doctors and college presidents -- to pass the hat.

Even Proxmire, who has given his share of "Golden Fleece" awards to silly-sounding NIH grants, views health research as a vital investment. "These are marvelous programs," said the senator, whose sister died of multiple sclerosis at an early age.

Most of the witnesses made sure to heap praise on the lawmakers. Those who supported their requests were hailed as courageous visionaries; opponents were, by implication, unfeeling penny pinchers.

"We are deeply appreciative of the work of this committee and especially you, Mr. Chairman," said Albert H. Owens, director of the Johns Hopkins Oncology Center.

"I want to thank all of you for the outstanding support, compassion and leadership you have shown," said Arlene Pessar, director of the Dystrophic Epidermolysis Bullosa Research Association.

These public hearings can grow tedious, and brevity is enforced by a red light that flashes four minutes into each presentation. Nonetheless, it is a ritual that the interest groups take seriously, right down to recruiting witnesses from Weicker's home state.

One subcommittee official said these annual show-and-tell sessions "may be a trade organization's only reason for being. They have to blanket the troops with paper showing what a great job they're doing."

The cameras were rolling, for example, when Dale Stuard, chairman of the Home Builders Institute, urged the panel to save the Job Corps from extinction. Aides filmed the talk for presentation at the group's next meeting.

"The hearings are fairly pro forma, but it's important that the people who care about the programs go on the public record," said the builders' LaVera Leonard. "It provides important boilerplate for the staff."

The Juvenile Diabetes Foundation is one of the smoothest practitioners of the art. The nonprofit health organization makes its case through a Washington law firm, a glossy annual report and ads filmed by its honorary chairman, Mary Tyler Moore.

Loring, a star of "Days of Our Lives," has a 10-year-old diabetic son, as she explained to key House and Senate members she visited this month. The group also dispatched a famous diabetic -- former Chicago Cubs third baseman Ron Santo -- to talk to Proxmire. The senator, as someone divined, is a lifelong Cubs fan.

The foundation distributed a fact sheet with all sorts of statistics on diabetes, the third leading cause of death in the United States. But perhaps none is more telling than this one: "There are approximately 25,000 people with diabetes in each congressional district."

Not to be outdone, the American College of Cardiology reminded the panel that heart disease is "the nation's number one killer." The American Association for Dental Research bemoaned the nation's annual dental bill, which it pegged at $24 billion.

As the senators listen to lesser known groups, from the American Academy of Orthopaedic Surgeons to the Association of Sleep Disorders Centers, the testimony becomes a numbing array of statistics that leaves one wondering how many healthy people are left in the country.

Mental disorders account for 25 percent of hospital inpatient stays at a cost of $6 billion a year, says one witness. Mental illness, alcoholism and drug abuse affect up to 45 million Americans and drain $185 billion a year from the economy, says another. Arthritis costs the country $20 billion a year and the toll will soar to $100 billion in 15 years, says a third.

The lawmakers have a passing interest, of course, in how the money they approve is spent. When Congress created six digestive disease centers last year, one happened to be placed at Yale University, in Weicker's state. And Yale dispatched one of its professors, Joyce D. Gryboski, to urge the panel to approve another $10 million for four new centers, plus $2 million for a digestive diseases data system.

"Digestive diseases rank second only to cardiovascular diseases as a cause of disability due to illness in the United States and are the primary cause of over 190,000 deaths each year," said Gryboski, a member of the National Digestive Diseases Advisory Board. "These diseases include more than 40 acute and gastrointestinal conditions, ranging from common illnesses such as heartburn, gallstones, diarrhea and hemorrhoids to . . . cirrhosis, inflammatory bowel disease and cancer."

In the end, though, nothing beats the personal appeal. Barbara Matia, an arthritis victim, argued for research on an antibiotic that she said transformed her "from a jaundiced, heartbroken, dying wife and mother to an active, vital woman."

Matia put the issue more bluntly than most. "The political decision," she said, "is whether this subcommittee thinks the 37 million arthritics are worth $2.2 million, which could potentially lead to the availability of the best treatment program for arthritis yet known."

Does this sort of testimony make it difficult for senators to say no?

"You bet it does," Proxmire said. "We're all human beings. You remember it; it touches you. You think, my God, I'll write them a check myself."