Diabetes treatment becoming more complex, more expensive

In a survey of trends in diabetes treatment from 1994 to 2007, investigators observed an increasing incidence of diabetes, a greater variety of drugs and combinations available for treatment, and a marked increase in the annual cost of diabetes medications. The investigators state that the current lack of cost-effectiveness data raises questions about whether these more expensive drug therapies are associated with a corresponding improvement in treatment outcomes. These results were published in the Archives of Internal Medicine.

For this study, investigators analyzed data from the National Disease and Therapeutic Index (NDTI), which is a physician survey conducted by IMS Health. The NDTI collects data from approximately 3,500 office-based physicians. For this analysis, investigators focused on visits from patients who were diagnosed with diabetes and treated with at least 1 medication (defined as treatment visits). The investigators attempted to limit their analyses to patients with type 2 diabetes by including patients aged >35 years who had been diagnosed with diabetes and by excluding patients who had received a diagnosis associated with type 1 diabetes. Information on prescription expenditures was obtained from the National Prescription Audit (NPA), a national sample of approximately 20,000 retail, mass merchandise, and mail-order pharmacies.

The number of patient visits for type 2 diabetes increased from 29 million in 1994 to 37 million in 2000 and to 45 million in 2007. The proportion of visits increased among ethnic minorities (from 23% in 1994 to 33% in 2007), among women (from 45% in 1994 to 51% in 2007), and among patients aged
The number of treatment visits increased from 25 million in 1994 to 30 million in 2000 and to 36 million in 2007. The mean number of diabetes medications prescribed increased from 1.06 per treatment visit in 1994 to 1.45 per treatment visit in 2007. In 1994, these medications included insulin formulations (38%) and sulfonylureas (67%); by 2007, these percentages had shifted considerably, owing to newly available drug classes (metformin, 54%; sulfonylureas, 34%; glitazones, 28%; insulin, 28%; sitagliptin, 8%; exenatide, 4%).

Prescriptions for newer insulin preparations have been increasing; prescriptions for ultrashort-acting insulin analogues and combinations that include these preparations have increased from 2% of treatment visits in 2001 to 7% in 2007. Long-acting insulin analogues have also become more prevalent (increasing from 2% in 2001 to 12% in 2007). The use of older insulin preparations and combinations including these preparations has steadily declined.

Prescriptions for sulfonylureas also decreased over the course of the study period. Combination drugs that include sulfonylureas were prescribed at 11% of treatment visits in 2003 but at only 6% of treatment visits in 2007.

Metformin was prescribed at 18% of treatment visits in 1996 and at 38% of treatment visits in 2000; its use increased to 54% of treatment visits in 2007. By 2007, metformin-containing combination drugs, including metformin plus sulfonylureas, metformin plus glitazones, and metformin plus sitagliptin, were prescribed at 12% of treatment visits.

Prescriptions for glitazones peaked at 34% in 2005 and decreased to 28% by 2007, with a significant reduction in use apparent during 2007. In 2004, rosiglitazone was the most commonly used glitazone (59%); by 2007, pioglitazone had become the most commonly used glitazone (64%).

Sitagliptin and exenatide, which were introduced to the US market in 2006 and 2005, respectively, have been rapidly adopted in clinical practice; several more years of follow-up data are necessary to determine what place these agents will ultimately have in therapy for diabetes.

Between 2001 and 2007, drug expenditures for diabetes increased by 87% (from $6.7 billion in 2001 to $12.5 billion in 2007). The mean price of a diabetes medication increased from $56 in 2001 to $76 by 2007; much of this increase was caused by increasing use and high prices of glitazones ($160 in 2007), ultrashort-acting insulin ($156 in 2007), long-acting insulin ($123 in 2007), exenatide ($202 in 2007), and sitagliptin ($160 in 2007). The costs of metformin and sulfonylurea decreased over the course of the study (from $63 to $29 and from $27 to $20, respectively).

The authors pointed out that these results demonstrate “the increasing complexity and costs of diabetes pharmacotherapy.” They also said that cost-effectiveness analyses are needed, stating that “substantial outcome differences would be needed to overcome the high cost of the newer drugs, with prescription costs for glitazones, exenatide, and sitagliptin 8 to 10 times those of sulfonylureas and 5 to 7 times those of metformin.”

SourceAlexander GC, Sehgal NL, Moloney RM, Stafford RS. National trends in treatment of type 2 diabetes mellitus, 1994–2007. Arch Intern Med. 2008;168:2088–2094.