Diabetes treatments are now the leading driver of prescription drug spending growth, displacing lipid-lowering drugs which fell precipitously after a decade of reigning in the top position, as generic drugs cut the cost of treating high cholesterol.

The report shows that despite continued growth in the use of cholesterol drugs, spending fell 8.5 percent in 2007 as usage of lower-cost generic versions of Pravachol and Zocor expanded in the marketplace, resulting in lipid-lowering medications experiencing the greatest spending decline of all drug categories. Meanwhile, spending on diabetes drugs increased 12 percent due to shifts toward higher-cost treatments, brand-name drug price inflation, and moderate growth in the number of patients receiving treatment.

For a decade, cholesterol drugs were the largest driver of drug trend - a measure of spending growth for pharmacy benefit plans. These medications still account for a sizable 10.8 percent of all prescription costs with utilization rising 5.9 percent last year as new clinical guidelines expanded the population that can benefit from these treatments.