Saxagliptin Added to a Thiazolidinedione Improves Glycemic Control in Patients with Type 2 Diabetes and Inadequate Control on Thiazolidinedione Alone

Context: Due to the natural progression of type 2 diabetes (T2D), most patients require combination therapy to maintain glycemic control. Objective: Our objective was to evaluate efficacy and safety of saxagliptin plus thiazolidinedione (TZD) in patients with T2D and inadequate glycemic control on TZD monotherapy. Design: The study was a multicenter, randomized, double-blind, placebo (PBO)-controlled phase 3 trial conducted from March 13, 2006, to October 15, 2007. Setting: Patients were recruited from 172 outpatient centers. Patients: Patients with inadequately controlled T2D [glycosylated hemoglobin (HbA(1c)) 7.0-10.5%], 18-77 yr, receiving stable TZD monotherapy (pioglitazone 30 or 45 mg or rosiglitazone 4 or 8 mg) for at least 12 wk before screening were eligible. Interventions: A total of 565 patients were randomized and treated with saxagliptin (2.5 or 5 mg) or PBO, once daily, plus stable TZD dose for 24 wk. Main Outcome Measures: Primary outcome was change in HbA(1c) from baseline to wk 24. Secondary outcomes were change from baseline to wk 24 in fasting plasma glucose, proportion of patients achieving HbA(1c) less than 7.0%, and postprandial glucose area under the curve. Results: At 24 wk, saxagliptin (2.5 and 5 mg) plus TZD demonstrated statistically significant adjusted mean decreases vs. PBO in HbA(1c) [-0.66% (P = 0.0007) and -0.94% (P < 0.0001) vs. -0.30%] and fasting plasma glucose [-0.8 mmol/liter (P = 0.0053) and -1 mmol/liter (P = 0.0005) vs. -0.2 mmol/liter]. Proportion of patients achieving HbA(1c) less than 7.0% was greater for saxagliptin (2.5 and 5 mg) plus TZD vs. PBO [42.2% (P = 0.001) and 41.8% (P = 0.0013) vs. 25.6%]. Postprandial glucose area under the curve was significantly reduced [-436 mmol . min/liter (saxagliptin 2.5 mg plus TZD) and -514 mmol . min/liter (saxagliptin 5 mg plus TZD) vs. -149 mmol . min/liter (PBO)]. Saxagliptin was generally well tolerated; adverse event occurrence and reported hypoglycemic events were similar across all groups. Conclusions: Saxagliptin added to TZD provided statistically significant improvements in key parameters of glycemic control vs. TZD monotherapy and was generally well tolerated. (J Clin Endocrinol Metab 94: 4810-4819, 2009)