First study to show cost-effectiveness of pre-diabetes intervention

Feb 28 2005

More than 40 million Americans face a high risk of developing Type 2 diabetes, and it would cost a lot to give all of them intensive help with diet and exercise, or medication, to keep them from developing diabetes.

But not helping them would cost a lot, too -- and would do nothing to stem the nation's diabetes epidemic and its vastly expensive medical consequences, according to a new study in the March issue of the Annals of Internal Medicine.

The study is the first to show that it would be cost-effective for society to try to prevent diabetes in people with a condition known as "pre-diabetes," or impaired glucose tolerance. An estimated 41 million Americans have the condition, in which blood sugar levels are higher than normal. Pre-diabetes is closely linked to obesity.

The new research shows that the costs of diabetes prevention are well within the range that American society has previously accepted for other preventive and curative health efforts.

The authors, led by a diabetes researcher from the University of Michigan Health System, conclude that American health policy should immediately begin promoting diabetes prevention in high-risk people. An accompanying editorial, by the leader of a large Finnish diabetes study, concurs.

The findings are based on sophisticated computer modeling of data from a large national clinical trial completed in 2001. It showed that in just three years, a one-on-one weight loss and exercise program substantially reduced the chance that a person with pre-diabetes would develop diabetes. It also showed that a diabetes drug called metformin can have a smaller, but still significant, preventive effect.

That study of 3,234 Americans, called the Diabetes Prevention Project, was funded by the National Institutes of Health, the Centers for Disease Control and Prevention, the American Diabetes Association and two pharmaceutical companies.

"By projecting the DPP's findings into the future, and factoring in all costs including the future cost of diabetes complications, we were able to show cost-effectiveness on a societal basis, and in some age groups, cost savings compared with no action," says lead author William Herman, M.D., MPH, director of the Michigan Diabetes Research and Training Center at UMHS.

Three years after DPP's results were published, he says, it hasn't had the major impact on clinical practice that the researchers would have hoped for, because of cost concerns. He hopes the new paper will change that.

"The bottom line is, we shouldn't be asking if we can afford to reach out to every at-risk person and help them reduce their risk," says Herman. "The real question is, in the face of today's epidemic of obesity, can we afford not to?"

About half of the DPP participants were African American, American Indian, Asian American, Pacific Islander, or Hispanic American/Latino, because of the high risk of Type 2 diabetes in those groups. The DPP lifestyle intervention included brisk walking for 30 minutes five days a week, lowered fat and calorie intake, and a weight-reduction goal of 7 percent of body weight. Those who took metformin, and those in the placebo group, received information on exercise and diet.

In just three years, the risk of developing Type 2 diabetes was reduced by 58 percent among those in the lifestyle change group, and 31 percent in the metformin group.

The new study's computer model shows that a lifestyle-change program could delay the onset of diabetes by an average of 11 years and reduce the risk of developing diabetes by 20 percent, when compared with no intervention. Twice-daily doses of 850 milligrams of metformin would delay the onset by 3 years, on average, and lead to an 8 percent reduction in the overall risk of diabetes.

Neither intervention would prevent every case of diabetes. But both approaches would spare many individuals, and society, the costs of long-term blood-sugar monitoring and medications, and the cost of treating the expensive complications of diabetes that may occur later in life, including blindness, kidney failure, disabling nerve damage and heart disease.

The result would be a better quality of life, and longer life, than many would have otherwise had. The researchers used a measure called a "quality adjusted life year" or QALY to calculate how diabetes and its complications, or delaying the onset of diabetes, would affect the length and quality of a person's life.

"The QALY measure is often used to evaluate whether spending money on a treatment is worthwhile for society," explains Herman, a professor of internal medicine at the U-M Medical School and of epidemiology at the U-M School of Public Health. "Preventive steps that cost less than $20,000 per QALY are generally considered affordable. There's debate over the value of treatments that cost more than that. Those over $100,000 are often considered to be too expensive."

The new analysis showed that, over a lifetime, intensive lifestyle interventions for people with pre-diabetes would cost society $8,800 for every QALY saved, making it highly cost-effective.

This number includes costs of both the intervention and of an individual's medical care for all conditions, related to diabetes or not. If the lifestyle efforts were done in small groups rather than one-on-one, the cost would be less. And even if the diabetes-delaying effects of the lifestyle intervention were half of what was observed in the DPP, the effort would still be cost-effective.

On the other hand, giving people with pre-diabetes doses of metformin to reduce their blood sugar would cost society $29,000 per QALY saved, if the brand-name drug Glucophage was used, the researchers found. If a generic equivalent drug was used, the cost would be less. Metformin was still within the cost-effective range for most people, except those over age 65.

The researchers also calculated the direct medical costs (or savings) of the intervention (lifestyle change, medication or placebo) and the direct cost of diabetes care and treatment of complications.

In this analysis, the lifestyle-modification option would actually cost less than placebo for people between the ages of 25 and 44; for people who took part in group sessions rather than individual sessions; and even for people who got half as much benefit from the program as DPP participants.

In addition to Herman, the study's authors are Thomas Hoerger, Ph.D., Michael Brandle, M.D., M.S., Katherine Hicks, M.S., Stephen Sorenson, Ph.D., Ping Zhang, Ph.D., Richard Hamman, M.D., Dr.PH., Ronald Ackerman, M.D., MPH, Michael Englegau, M.D., M.S. and Robert Ratner, M.D., for the DPP Research Group. The editorial accompanying the paper is by Jaakko Tuomilehto, M.D., Ph.D., MPolSc, of the University of Helsinki, Finland.