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

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.