Trends in treating type 2 diabetes

Availability of newer medications, increasing number of medications have led to more complexity, higher costs of treating diabetes.

A recent manuscript in the Archives of Internal Medicine described the trends in treating type 2 diabetes from 1994 to 2007.

The idea was to examine how the introduction of newer agents over the past decade have influenced prescribing patterns and drug cost. The authors used data from the National Disease and Therapeutic Index, an ongoing physician survey, to collect information on prescribing trends for type 2 diabetes. Data on drug costs was obtained from the National Prescription Audit, which provides a nationally representative sample from various pharmacies.

This column serves to highlight some of the findings of this important manuscript.

Changes in office-based visits, medication use

Estimated office visits for type 2 diabetes increased from 29 million in 1994 to 45 million in 2007. During this time, there was a notable increase in visits by ethnic minorities and women and patients younger than 60 years. However, the mean number of annual office visits per patient decreased from 2.9 to 2.4.

Not surprisingly, there were significant changes in medication use over this time. In 1994, 38% of treatment visits involved use of an insulin therapy and 67% involved use of a sulfonylurea. In 2007, metformin (Glucophage, Bristol Myers Squibb) was used in 54% of office visits, thiazolidinediones in 28%, sitagliptin (Januvia, Merck) in 8%, and exenatide (Byetta, Amylin) in 4%. Insulin and sulfonylurea use decreased to 28% and 34%, respectively.

James R. Taylor, PharmD, CDE

In 1994, regular and intermediate insulins accounted for nearly all insulin use. The introduction of newer insulin analogues (rapid and long acting) led to a shift in the types of insulins now most commonly used. As of 2007, the insulin analogues are now more commonly prescribed than regular and intermediate acting insulins. In 2007, the most commonly prescribed insulins were insulin glargine (Lantus, Sanofi-Aventis) and insulin lispro (Humalog, Eli Lilly).

Sulfonylureas were previously the primary treatment for type 2 diabetes. With the introduction of newer medications with novel mechanisms of action, their use has declined dramatically. Glipizide (Glucotrol XL, Pfizer) is now the most commonly used sulfonylurea as a single agent; glyburide plus metformin and glimepiride plus a TZD are the most common combination products now used.

The use of metformin has steadily increased since it was introduced — from 18% of office visits in 1996 to 54% in 2007. Metformin combination products are also commonly used and accounted for 12% of office visits in 2007.

The TZD troglitazone was rapidly incorporated into treatment plans soon after its introduction and accounted for 10% of treatment visits in 1998. It was removed from the market in 2000 due to concerns of hepatotoxicity. Rosiglitazone (Avandia, Glaxo Smith Kline) and pioglitazone (Actos, Takeda) were introduced in 1999 and accounted for 34% of office visit subscriptions in 2005. Their use has subsequently decreased.

While little data were available for the newer medications, such as sitagliptin and exenatide, the numbers indicate that they have been widely incorporated into treatment regimens. Not all of the newer agents have been as widely accepted — α-glucosidase inhibitors were reportedly used in less than 0.5% in 2007. Likewise, metaglinides and pramlinitide (Symlin, Amylin) only accounted for 2% and less than 0.5%, respectively, in 2007.

Drug costs

With the advent of newer medications, drug expenditures increased by 87% from 2001 to 2007. The mean price for a diabetes drug increased from $56 in 2001 to $76 in 2007.

The only drugs that saw a decrease in price over this time were metformin and sulfonylureas, due to the availability of generic formulations.

The introduction of newer drugs and combination products, along with increasing number of diabetes medications each patient takes, has led to increased complexity and costs of treating diabetes.

Continued research demonstrating the outcomes of these newer agents would help justify these increased costs. Of note, the mean HbA1c level in patients with diabetes decreased from 7.6% in 1999 to 2000 to 7.1% in 2003 to 2004. As the authors point out, cost-benefit analysis would help determine if increasing treatment costs are balanced by improved outcomes.

James R. Taylor, PharmD, CDE, is a Clinical Associate Professor in the Department of Pharmacy Practice at the University of Florida.

For more information:

• Alexander GC, Sehgal NL, Mooney RM, Stafford RS. National trends in the treatment of type 2 diabetes mellitus, 1994-2007. Arch Intern Med. 2008;168:2088-2094.