The Outcomes and Costs of Diabetes Prevention with a Diet and Exercise Program or Metformin: A Computer Model

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The summary below is from the full report titled "Clinical Outcomes and Cost-Effectiveness of Strategies for Managing People at High Risk for Diabetes." It is in the 16 August 2005 issue of Annals of Internal Medicine (volume 143, pages 251-264). The authors are D.M. Eddy, L. Schlessinger, and R. Kahn.

What is the problem and what is known about it so far?

Type 2 diabetes mellitus interferes with the body's ability to store energy from food. The result is high blood sugar levels that can lead to complications, such as blindness, kidney failure, and heart disease. Many people with type 2 diabetes have moderately high levels of blood sugar for years before the levels reach true diabetes levels and symptoms begin. This condition is called abnormal glucose tolerance or "prediabetes." A large study showed that 2 different methods can prevent or delay the development of diabetes in people with prediabetes. The first method is an intensive diet and exercise program supervised by a clinic. The other is a small daily dosage of a diabetes medication called metformin. Because many Americans have prediabetes, using 1 of these prevention methods in all people who might benefit would be expensive. However, caring for diabetes and its complications is also expensive. It is important to know whether the costs of diabetes prevention are worth the potential benefits. A previous analysis using a computer model estimated that, compared with no prevention, the diet and exercise program would cost about $8800 and metformin about $29,000 per quality-adjusted year of life saved.

Why did the researchers do this particular study?

To estimate whether the costs of using an intensive clinic-based diet and exercise program or metformin to prevent type 2 diabetes is worth the potential benefits.

Who was studied?

Rather than studying actual patients, the researchers used computers to simulate what would happen to a virtual group of adults with prediabetes.

How was the study done?

The researchers used published information to estimate what might happen (and how much it would cost) if doctors prescribed an intensive clinic-based diet and exercise program or metformin for adults with prediabetes. They put these estimates into a computer model called the Archimedes model and calculated how much each strategy would cost per year of life saved. The Archimedes model includes more detailed biological and administrative information than models typically used to conduct these types of analyses.

What did the researchers find?

Both the diet and exercise program and the metformin program would benefit people with prediabetes. However, the program provides more than twice the degree of benefit as metformin. The program is more expensive than metformin, costing approximately $672 a year. Compared with no program at all, and taking its benefits into account, it would cost society about $62,600 per quality-adjusted year of life saved. The diet and exercise program would save money if its yearly cost could be decreased from $672 to $100.

What were the limitations of the study?

We can never be certain how well a computer model represents what would happen with real patients over long time periods. Much of the information on use of health care services was based on data from Kaiser Permanente and may not accurately represent other health care settings.

What are the implications of the study?

These authors confirm that a clinic-based diet and exercise program has important benefits for people with prediabetes. However, they estimate that the cost to society of a formal clinic-based program per amount of benefit is higher than previous estimates.