In 1999, Peggy Bryant, a fifty-year-old oncology nurse in Boston, received a postcard asking whether she’d like to take part in a clinical trial aimed at preventing diabetes. Well, this is fitting, she thought. How many patients have I asked to enroll in trials? Bryant, who’d long struggled with her weight, told me that she had cared for people dealing with grave complications of diabetes—vision loss, kidney failure, limb amputations—and had worried that “full-blown diabetes might be in my future.” She decided to sign up. Some of the trial’s participants were given a medication called metformin; others were given a placebo. Bryant was assigned to a third group, in which volunteers didn’t receive a pill but instead worked with trial staff to meet their health goals, exercise more, and lose weight. About once a month, she gave blood and urine samples. “It changed the way I approached my health,” she told me. “The staff were so committed that it made you more committed.” The study found that, in people with prediabetes, metformin lowered the risk of diabetes by roughly a third; the life-style intervention cut the risk by more than half. Both components were so successful that the trial was stopped early. (All participants got the life-style intervention for a year; since then, the study has mostly been observational.) The Secretary of Health and Human Services held a press conference to announce the findings. “I’ve been doing this a long time, and I’ve never heard of a study’s results being announced by the head of H.H.S.,” David M. Nathan, a Harvard professor who chaired the study, told me. “It was a big fucking deal.”

Diabetes is a lifelong condition whose consequences can be varied: nerve damage, heart disease, digestive problems, foot ulcers. It affects nearly forty million Americans and kills more than a hundred thousand each year. “Studying it for three or five years seemed shortsighted,” Nathan said. His team applied for funding to extend their project and consider follow-up questions. How long do the health benefits last? How do blood-sugar levels affect the body and the brain over time? For more than a quarter of a century, Nathan and his colleagues tracked thousands of patients—which was itself a feat of logistical and scientific endurance. (Many doctors struggle to get their patients to attend annual physicals, let alone engage them for a study of this duration.)

The Diabetes Prevention Program Outcomes Study, as the project is known, has led to more than two hundred scientific publications. Simply by continuing to exist, it has overcome one of the central difficulties of chronic-disease research: time. Most studies enroll patients for months or for years. But, if you want to prove that a drug or a life style can extend a person’s life—not in theory but in fact—you have to follow them for, well, much of their life. And to study a condition with wide-ranging effects, such as diabetes, you tend to gather wide-ranging data: genetic information, dietary habits, imaging, metabolic markers. The study collected hundreds of thousands of samples, which serve as a sort of time capsule of America’s health. Such troves of medical information can often lead to unexpected breakthroughs. This month, a study found that the people who’d participated in a rigorous diet-and-exercise program in the late nineteen-nineties, as Bryant did, were substantially less likely to develop diabetes decades later. Midlife investments in health compound into older age. As the study’s participants have aged, researchers have turned their focus to a link between diabetes and dementia.

The study’s funding comes from the National Institutes of Health, which in 2022 committed some eighty million dollars to cover five years of further research, one of its largest grants. The N.I.H. sends the money to a coördinating center—in this case, Columbia University—which then distributes the funds to dozens of participating trial sites around the country. But, in early March, the Trump Administration froze hundreds of millions of dollars in funding to Columbia, and the diabetes study was abruptly terminated. Columbia informed collaborators at other institutions that trial-related work needed to stop immediately. “We had to call some participants that night and tell them not to come in the next day,” Nathan said. Bryant, who now lives in New York City, got a call from a study coördinator at Montefiore Einstein Medical Center informing her of the cancellation. “I was shocked,” she said. “It just seemed so pointless.” A few days later, she joined other Montefiore study participants on a Zoom call with the site’s lead researcher and a member of the study’s executive committee, an endocrinologist named Jill Crandall. Even the N.I.H. team overseeing the grant had been blindsided, Crandall told me. They learned of the termination not from the government for which they work but from the study’s leaders. “They were completely in the dark,” she said.

When Bryant joined the trial, her daughter was a child; her daughter now has two children of her own. On the Montefiore video call, Bryant noticed an older man who looked ill—a fellow-participant who appeared to be sleeping or unconscious. The man’s wife was there with him. She held his hand as she explained that he had dementia, and that it had progressed. She wanted everyone to understand the stakes of the research they’d been engaged in. Perhaps hidden somewhere in the time capsule was a key to prevent, or at least delay, such an outcome. “I thought, Wow, that could be any of us one day,” Bryant told me. “We should be doing more—a lot more. Instead, here we are, moving in the wrong direction.”

Robert F. Kennedy, Jr., the Trump Administration’s Secretary of Health and Human Services, has called chronic diseases such as diabetes an “existential threat.” He has railed against the food industry, calling sugar a “poison” and labelling high-fructose corn syrup “a formula for making you obese and diabetic.” Strangely—perhaps incoherently—his agency is also responsible for ending a diabetes study that has been running for longer than any other. In recent months, H.H.S., which oversees the Centers for Disease Control and Prevention, the Food and Drug Administration, the Centers for Medicare and Medicaid Services, and nearly a dozen other entities, has cut some twenty thousand jobs, or about a quarter of its workforce. (Kennedy has acknowledged that the mass layoffs could result in many mistakes.) A C.D.C. unit that works to prevent childhood lead poisoning was purged. Another unit dedicated to helping people stop smoking, the country’s leading cause of preventable death, was also eliminated. At the F.D.A., veterinarians focussed on curtailing the risks of the ongoing bird-flu outbreak were let go; some fired employees at C.M.S. were told to direct their complaints to an administrator who died last year. “I have no argument with the need for government to do things better and more efficiently,” Richard Besser, a former C.D.C. director, told me. “But this is not about that. This is about tearing down institutions they don’t like. I doubt that rebuilding them will be possible in my lifetime.”

Patients are already feeling the effects. It’s estimated that at least a hundred clinical trials are at risk of stopping or have already halted, including some dedicated to preventing sexually transmitted infections, reducing rates of postpartum depression, and keeping organ-transplant recipients safe from infectious threats. More may soon follow. Bryant told me that she’s been working at a contract research organization that helps enroll patients in trials. Even studies sponsored by the pharmaceutical industry are being affected: many rely partially on federal funding, or are run by staff who do, and who have consequently been laid off. An oncologist told me about a patient with Stage IV cancer who, until recently, had three options for experimental trials. She now has none. Meanwhile, people who have never participated in a trial will suffer the costs of unrealized discoveries—potential treatments and insights that never materialize.

The lapse in funding means that the Diabetes Prevention Program Outcomes Study can no longer continue to collect patient data as planned; it can no longer pay staff to do blood work, collect urine samples, scan brains, or conduct neurocognitive tests. Even worse, the study’s existing data are at risk. Scientists need funds to properly store and retrieve samples; they need money to pay for computer servers and to hire statisticians and analysts, who clean and curate the data. (Although the N.I.H. stores some study samples, the agency has told researchers that it doesn’t have the capacity to accept the entire collection.) “The absence of funding could prevent us from continuing to maintain the integrity of the database,” Nathan, the Harvard professor, told me. “It’s a tremendous waste of resources.” The contents of the time capsule may become irrecoverable.

In recent weeks, Nathan, Crandall, and others involved with the study have worked furiously to try to have the N.I.H. funding restored. They’ve spoken with agency representatives and members of Congress. They’ve gone to the media and lobbied professional societies. In March, the bipartisan chairs of the Congressional Diabetes Caucus sent a letter to Kennedy and the N.I.H. acting director, urging them to “take necessary action” to insure that the diabetes study continues. (The N.I.H. and H.H.S. did not respond to my requests for comment.)

The longer that the trial is paused, the harder it will be to resume. Trial staff at the various clinical sites, with whom some participants have decades-long relationships, are already being laid off. “People think trials are just about collecting data, but there’s an art to keeping participants invested and engaged,” Crandall said. “That personal connection will fade.” She told me about an older participant who’d recently passed away. The woman didn’t have much family; a friend organized her memorial service and wound up inviting the study team. At the service, the friend spoke about how much the study had meant to the woman—how, through it, she felt that she was contributing to something larger than herself, something that might help others. “That’s what a trial like this can be,” Crandall said. “If we let this study fade, it will never be duplicated. No one else is going to do it.” ♦