Comparison of hemoglobin A1c goal achievement with the addition of pioglitazone to maximal/highest tolerated doses of sulfonylurea and metformin combination therapy

OBJECTIVES: It has been proposed that the combination of thiazolidinedione (TZD) therapy to metformin and sulfonylurea is beneficial due to each medication having a unique mechanism of action. Within the Veterans Affairs Hospital, specific criteria of use define when TZD therapy can be initiated. Most patients who receive TZD therapy have failed other medications prior to use. The primary objective of this study was to determine the percentage of patients achieving the American Diabetes Association (ADA) goal hemoglobin A1c (A1c) of less than 7% with the addition of pioglitazone to the maximal/highest tolerated doses of sulfonylurea and metformin combination therapy. METHODS: This was a six healthcare system retrospective, descriptive, analysis of type 2 diabetic patients (DM-2). Patients must have received the maximal/highest tolerated doses of sulfonylurea and metformin combination therapy and have been TZD naïve or off TZD therapy for a minimum of 6 months, a baseline A1c greater than 7%, a repeat A1c at 3 and 6 months available, and deemed medication compliant. RESULTS: We evaluated 98 total patients. The percentage of veteran patients achieving ADA goal A1c of less than 7% after the addition of pioglitazone reached statistical significance at both 3 and 6 months post TZD initiation. The mean reduction in A1c post-pioglitazone initiation was 0.67% (SD ± 0.92) and 0.78% (SD ± 0.94) at 3 and 6 months, respectively. CONCLUSION: The addition of pioglitazone to veteran patients who were already receiving maximal/highest tolerated doses of sulfonylurea was able to achieve a higher percentage in with the ADA goal A1c of less than 7%. Initiating pioglitazone in patients with an A1c of 9% or greater did not reach statistical significance in achieving an A1c less than 7%. The initial starting dose of pioglitazone 30 mg can be considered as compared to 15 mg daily if contraindications do not exist.