WASHINGTON — A diabetic in Ohio sends basic medical information each night to a nurse who may be a thousand miles away. If a significant condition change is detected, the nurse calls to find out why and contacts the patient's doctor and pharmacist.

The goal of this heightened monitoring is to prevent a medical crisis that could send the patient to the hospital. Such coordinated care for people with chronic illnesses such as diabetes, heart disease and high blood pressure is the focus of disease management programs, which got a big boost in the Medicare law signed by President Bush last week. It is these patients who consume most health care dollars.

The government hopes to enroll as many as 400,000 older people with chronic conditions in these programs. By involving the patient, physicians, pharmacists and other providers in commonsense steps to improve patient health, the government seeks to limit costly hospital stays.

"We want to prevent diabetics from becoming dialysis patients," said Rep. Nancy Johnson, R-Conn., a leading supporter of including disease management in Medicare.

The chronic care effort, plus a new Medicare physical and other preventive screenings, are a marked change in the 38-year-old government health care program for 40 million older and disabled Americans. Traditionally, Medicare has paid for treating illnesses, not preventing them.

But the number of Medicare beneficiaries with chronic conditions is large and growing, said Mark Miller, executive director of the federal Medicare Payment Advisory Commission.

Three-fourths of Medicare beneficiaries have at least one chronic condition, and close to one-third have four or more, Miller said. These people account for 80 percent of Medicare spending.

Such numbers make the benefit of early intervention indisputable, said Health and Human Services Secretary Tommy Thompson.

"It is better for us to start managing diabetes, hypertension, asthma and other conditions before they get exacerbated," Thompson said. "It will save us money in the long run."

Programs in place on a small scale are demonstrating savings, proponents of disease management say.

At Aetna Inc., 3,000 people with chronic heart failure are in a disease management program that has produced a 17 percent drop in costs and a 32 percent reduction in hospitalizations, according to John W. Rowe, the company's chairman and chief executive officer.

Among obstacles to making the programs work smoothly are persuading people to enroll and coordinating care among a dozen or more doctors who may be treating patients with several illnesses.

"Particularly in the elderly population, you have an increased level of suspicion and of people being set in their ways," said Christobel Selecky, chief executive of Lifemasters of Irvine, Calif., a private disease management company.

The Medicare program will select up to 10 regions of the country that cover a total of about 4 million clients, said Stuart Guterman of the Centers for Medicare and Medicaid Services. Using recent medical claims, officials will try to concentrate on about 40,000 people in each region who could most benefit.

The government will contract with private companies, which will sign up patients and take charge of coordinating the care. The new push for chronic care is a boon for Lifemasters and others that use nurses and in some cases computers to facilitate frequent communication with patients.

The companies must show a drop in health care claims by an amount at least equal to their fees, or the companies will have to repay the government, the law says.

Disease management companies had combined revenues of $600 million last year and are growing rapidly as the population ages, said Selecky, who also is president-elect of the Disease Management Association of America.

Lifemasters, which works with 300,000 patients around the country, runs a disease management program with the State Teachers Retirement System of Ohio. For more than a year, James Williams, 61, of Wheelersburg, Ohio, has checked his blood sugar levels four times daily. Using a toll-free number, he enters the information each night using his telephone key pad.

If the numbers are too high or low, "they call the next morning to see how I am, and they also notify my doctor," Williams said. "To me, it's another form of accountability."

In addition, a Lifemasters nurse calls Williams the first and third Friday of every month to talk about his health, he said.

In a program involving several hundred veterans in Florida, a small countertop computer called a Health Buddy asks patients how they feel and allows them to transmit information.

"It's a daily check in," said Steve Brown, chief executive of Health Hero Network of Mountain View, Calif., maker of the computer. "It's something that breaks the cycle of isolation and crisis. You can have a huge impact if you just provide people with continuity of care."