Treatment approach and HbA_1c control among US adults with type 2 diabetes: NHANES 1999–2004

ABSTRACT

Objective: To examine the distribution of diabetic medications among adults with type 2 diabetes, and the association between glucose control and treatment approach in the US population.

Methods: Interview and prescription medication data from the 1999–2004 National Health and Nutrition Examination Survey (NHANES) were used to determine the treatment approach for US adults with type 2 diabetes. Mean glycosylated hemoglobin (HbA_1c) and the proportion of adults meeting recommended guidelines for glucose control were estimated for each treatment approach. The most important study limitation was that participants were not asked what type of diabetes they had. Among adults with diabetes, a classification algorithm was used to identify those with type 2 diabetes.

Results: During 1999–2004, approximately 60% of adults with type 2 diabetes used oral agents only to manage their diabetes. The distribution of oral treatment therapies changed over time (p < 0.01); the most prevalent treatment shifted from sulfonylurea monotherapy in 1999–2000 (23.0%) to any oral agent regimen containing thiazolidinedione (TZD) in 2003–2004 (21.4%). Overall, only 52.2% of adults with type 2 diabetes met the American Diabetes Association (ADA) goal for HbA_1c control (<7.0%) during 1999–2004. Across oral agent treatment categories, the proportion with HbA_1c controlled at the 7.0 level was significantly lower (p < 0.01) for those on triple therapy (31.9%) (TZD, sulfonylurea, and metformin), than those on metformin alone (62.2%), likely reflecting a progressive treatment approach of prescribing additional medications for those with uncontrolled HbA_1c levels.

Conclusions: Use of multiple oral agents among adults with type 2 diabetes has increased (sulfonylurea and metformin, p = 0.03, triple therapy, p = 0.02). However, nearly half of adults with type 2 diabetes have HbA_1c levels above ADA guidelines for control, indicating that available treatments could be used more optimally, and new diabetic agents may be needed.

Key words: :

• Glucose control
• HbA_1c
• NHANES
• Prescription medication
• Treatment
• Type 2 diabetes

Transparency

Declaration of funding

Eli Lilly and Company sponsored this study and provided financial support to Mathematica Policy Research, Inc.

Declaration of financial/other relationships

A.H.D., M.C., R.B. and C.F. have disclosed that they are employees of Mathematica Policy Research, Inc. K.S.B. has disclosed she is an employee and shareholder of Eli Lilly and Company and an executive board member of the EuroQol Group. S.K. has disclosed that she was a paid consultant to Eli Lilly, providing expert opinion on epidemiology and biostatistics.

All peer reviewers receive honoraria from CMRO for their review work. Peer Reviewer 1 has disclosed he/she has no relevant financial relationships. Peer Reviewer 2 has disclosed he/she has no relevant financial relationships.

Acknowledgment

The authors acknowledge the contributions of the following Mathematica Policy Research, Inc. employees: Nancy Clusen consulted on statistical approaches; Thomas Croghan provided thoughtful feedback on an earlier version of the manuscript; and Christal Stone served as the technical writer. Jim and Molly Cameron of Cameron Editorial Services edited the manuscript.

Notes

* Portions of this research were presented in a poster presentation at the 44th European Association for the Study of Diabetes Annual Meeting, Rome, Italy, 7–11 September 2008