National trends in treatment of type 2 diabetes mellitus, 1994-2007

Abstract

Background: Diabetes mellitus is common, costly, and increasingly prevalent. Despite innovations in therapy, little is known about patterns and costs of drug treatment.

Methods: We used the National Disease and Therapeutic Index to analyze medications prescribed between 1994 and 2007 for all US office visits among patients 35 years and older with type 2 diabetes. We used the National Prescription Audit to assess medication costs between 2001 and 2007.

Results: The estimated number of patient visits for treated diabetes increased from 25 million (95% confidence interval [CI], 23 million to 27 million) in 1994 to 36 million (95% CI, 34 million to 38 million) by 2007. The mean number of diabetes medications per treated patient increased from 1.14 (95% CI, 1.06-1.22) in 1994 to 1.63 (1.54-1.72) in 2007. Monotherapy declined from 82% (95% CI, 75%-89%) of visits during which a treatment was used in 1994 to 47% (43%-51%) in 2007. Insulin use decreased from 38% of treatment visits in 1994 to a nadir of 25% in 2000 and then increased to 28% in 2007. Sulfonylurea use decreased from 67% of treatment visits in 1994 to 34% in 2007. By 2007, biguanides (54% of treatment visits) and glitazones (thiazolidinediones) (28%) were leading therapeutic classes. Increasing use of glitazones, newer insulins, sitagliptin phosphate, and exenatide largely accounted for recent increases in the mean cost per prescription ($56 in 2001 to $76 in 2007) and aggregate drug expenditures ($6.7 billion in 2001 to $12.5 billion in 2007).

Conclusions: Increasingly complex and costly diabetes treatments are being applied to an increasing population. The magnitude of these rapid changes raises concerns about whether these more costly therapies will result in proportionately improved outcomes.

Figure 1

National trends in the use of different therapeutic drug classes to treat diabetes, 1997–2004. Data are from the IMS Health National Disease and Therapeutic Index; drugs from most new therapeutic classes (eg, dipeptidyl-peptidase-IV inhibitors) are omitted and reflected in the Table.

Figure 2

National trends in the use of different types of insulin to treat diabetes, 1994 to 2007. Data are from the IMS Health National Disease and Therapeutic Index and include combination products that contain these medications.

Figure 3

National trends in the amount spent per year on diabetes drugs, 2001 to 2007. Data are from the IMS Health National Prescription Audit and include combination products that contain these medications. “Other” includes secretagogues (eg, nateglinide), α-glucosidase inhibitors (eg, acarbose), dipeptidyl-peptidase-IV inhibitors (ie, sitagliptin phosphate), and incretins (ie, exenatide).

Figure 4

National trends in the amount spent per year on different types of insulin, 2001 to 2007. Data are from the IMS Health National Prescription Audit and include combination products that contain these medications.