Diabetes drug costs in the U.S. have almost doubled in six years to $12.5 billion as more people are diagnosed with the condition and patients receive newer, more expensive treatments such as Merck & Co.'s Januvia and Eli Lilly & Co.'s Byetta, a study found.

Researchers, writing in this week's issue of the Archives of Internal Medicine, questioned whether these newer drugs are more effective then older, cheaper treatments.

Diabetes, the inability to properly process sugar in the blood, is one of the world's fastest growing diseases, as people eat more and exercise less. About 18 million people in the U.S. were diagnosed with diabetes in 2007, an increase from 8.1 million in 1994, according to the Centers for Disease Control and Prevention, a U.S. agency in Atlanta. Worldwide sales of diabetes drugs may jump to $22 billion by 2016, analysts say.

"Are the newer costs worth it, is really the million dollar question," said lead author G. Caleb Alexander, an associate professor of medicine at the University of Chicago, in an Oct. 24 telephone interview. "The jury is still out if the greater costs we document are worth the money."

The study found the cost for diabetes drugs rose 87 percent to $12.5 billion in 2007 from $6.7 billion in 2001. Type 2 diabetes, which is linked to age, obesity and lack of exercise, accounted for as many as 95 percent of diabetes cases in the U.S. People with the condition don't produce enough insulin, or their cells ignore the insulin needed for the body to convert blood sugar to energy, according to the National Institutes of Health, a U.S. agency. The condition can lead to complications such as blindness, kidney damage and heart disease.

National Databases

Researchers in the study used two national databases to look at trends in diabetes treatment in patients ages 35 and older with type 2 diabetes who visited doctor's offices from 1994 to 2007. Information on drug costs was available from 2001 to 2007.

The authors attributed the rising number of diabetes cases to Americans' calorie-rich diets and sedentary habits, and because doctors are screening more intensively and diagnosing patients who have milder stages of the disease. The CDC has said an additional 5.7 million Americans have the condition and don't know it.

The researchers also found that more people are being prescribed more than one drug. In 2007, 47 percent of patients received only one diabetes treatment, down from 82 percent in 1994.

The average price of diabetes' prescriptions rose to $76 in 2007 from $56 in 2001, the authors said.

Five to 11 Times More

Newer drugs such as Merck's Januvia cost five to 11 times more than older, generic drugs such as metformin and glipizide, Alexander said. Januvia's third-quarter sales more than doubled to $379 million, the Whitehouse Station, New Jersey-based company said on Oct. 22.

Merck spokeswoman Amy Rose said developing and introducing new medicines for type 2 diabetes is "an important health priority."

"Not all diabetes treatments work for every patient, and it is important to research and bring new treatment options to market to help patients to control their blood-sugar levels," she said in an Oct. 24 e-mail. "The public health cost of diabetes is very high, but more than 80 percent of the cost is due to hospitalizations and outpatient care related to the management of diabetes-related complications. Drug cost represents less than one-fifth of the total cost."

Lilly spokeswoman Kindra Strupp said in an e-mail today that the company, along with marketing partner Amylin Pharmaceuticals Inc., temporarily assists low-income patients without public or private prescription drug coverage in obtaining Byetta.

`Step Back'

The study found benefits from diabetes drugs including an improvement in the national average of a blood test from 1999 to 2004. That blood test, called hemoglobin A1c, is a three-month average of blood sugar and indicates how well a person's diabetes is being managed. Still the researchers said that doesn't prove patients are benefiting from the newer drugs.

"This near-doubling of diabetes costs may partly reflect better care, but we need to step back and examine the value of newer and more costly medications that may be overused," said Randall S. Stafford, a study author and an associate professor at Stanford University in Palo Alto, California.

"Just because a drug is new or exploits a new mechanism does not mean that it adds clinically to treating particular diseases," he said in a statement from the university. "And even if a new drug does have a benefit, it's important to consider whether that benefit is in proportion to the increased cost of new therapies."

The research was funded by the Robert Wood Johnson Foundation, the Agency for Healthcare Research and Quality and the National Institutes of Health.

Separate Study

In a separate study in Archives, an analysis of 40 previous trials found that the generic diabetes treatment metformin is associated with lower risks of death from cardiovascular disease. Among other diabetes treatments, the researchers found no beneficial or harmful cardiovascular effects mostly because of insufficient data.

The authors of the cost study recommended doctors in many cases prescribe older, cheaper drugs before giving patients the newer, more expensive ones.

Alexander compared the diabetes treatments to those for other conditions such as cholesterol in which new, more expensive medicines haven't proven to be more effective.

"There's a familiar pattern here," he said.