CHICAGO » Americans with diabetes nearly doubled their spending on drugs for the disease in just six years, with the bill climbing last year to an eye-popping $12.5 billion.

Newer, more costly drugs are driving the increase, said researchers, despite a lack of strong evidence for the new drugs' greater benefits and safety. And there are more people being treated for diabetes.

The new study follows updated treatment advice for Type 2 diabetes, issued last week. In those recommendations, an expert panel told doctors to use older, cheaper drugs first.

In Hawaii more than 110,000 people have diabetes, roughly 8.6 percent of the population of 1,275,000, according to the Hawaii Diabetes Plan 2010, issued by the Health Department in 2005. Of those, an estimated 39,000 are undiagnosed.

Type 2 diabetes, when the body does not produce enough insulin or cannot use it properly, accounts for 90 percent to 95 percent of diabetes cases. That translates to 63,900 to 67,450 of the 71,000 diagnosed cases in Hawaii.

A typical person with Type 2 diabetes using insulin spends more than $700 per month on medication and supplies, according to the American Diabetes Association. At $8,400 per year for 67,450 people with diagnosed Type 2 diabetes in Hawaii, that adds up to $566.6 million per year.

Type 2 is often related to obesity or being overweight from a poor diet and/or sedentary lifestyle. But ethnic factors also play a part. Native Hawaiians, Filipinos and Japanese have a higher incidence than whites, according to the Health Department. Native Hawaiians also have the highest death rates from diabetes.

And a second study, also out yesterday, adds to evidence that metformin — an inexpensive generic used reliably for decades — could prevent deaths from heart disease while the newer, more expensive Avandia did not show that benefit.

The studies, appearing in yesterday's Archives of Internal Medicine, were both funded by federal grants.

In one, researchers from the University of Chicago and Stanford University looked at which pills and insulin doctors prescribed and total medication costs. Diabetes drug spending rose from $6.7 billion in 2001 to $12.5 billion in 2007, a period when costs dropped for metformin.

More patients got multiple prescriptions as new classes of drugs came on the market. And more patients with diabetes were seeing doctors, increasing from 14 million patients in 2000 to 19 million in 2007.

“;There's been a remarkable change in diabetes treatments and remarkable increases in the cost of treatments over the past several years,”; said study co-author Dr. Caleb Alexander, assistant professor of medicine at the University of Chicago. “;We were surprised by the magnitude of the changes and the rapid increase in the cost of diabetes care.”;

In the other study, Johns Hopkins University researchers analyzed findings from 40 published trials of diabetes pills that measured heart risks. Compared with other diabetes drugs or placebo, metformin was linked to a lower risk of death from heart problems.

The findings hint that Avandia has a possible increased risk for heart disease death, but that increase was not statistically significant, meaning it could have been the result of chance.