Effects of Exenatide Plus Rosiglitazone on β-Cell Function and Insulin Sensitivity in Subjects With Type 2 Diabetes on Metformin

OBJECTIVE: Study the effects of exenatide (EXE) plus rosiglitazone (ROSI) on β-cell function and insulin sensitivity using hyperglycemic and euglycemic insulin clamp techniques in participants with type 2 diabetes on metformin. RESEARCH DESIGN AND METHODS: In this 20-week, randomized, open-label, multicenter study, participants (mean age, 56 ± 10 years; weight, 93 ± 16 kg; A1C, 7.8 ± 0.7%) continued their metformin regimen and received either EXE 10 μg b.i.d. (n = 45), ROSI 4 mg b.i.d. (n = 45), or EXE 10 μg b.i.d. + ROSI 4 mg b.i.d. (n = 47). Seventy-three participants underwent clamp procedures to quantitate insulin secretion and insulin sensitivity. RESULTS: A1C declined in all groups (P < 0.05), but decreased most with EXE+ROSI (EXE+ROSI, −1.3 ± 0.1%; ROSI, −1.0 ± 0.1%, EXE, −0.9 ± 0.1%; EXE+ROSI vs. EXE or ROSI, P < 0.05). ROSI resulted in weight gain, while EXE and EXE+ROSI resulted in weight loss (EXE, −2.8 ± 0.5 kg; EXE+ROSI, −1.2 ± 0.5 kg; ROSI, + 1.5 ± 0.5 kg; P < 0.05 between and within all groups). At week 20, 1st and 2nd phase insulin secretion was significantly higher in EXE and EXE+ROSI versus ROSI (both P < 0.05). Insulin sensitivity (M value) was significantly higher in EXE+ROSI versus EXE (P = 0.014). CONCLUSIONS: Therapy with EXE+ROSI offset the weight gain observed with ROSI and elicited an additive effect on glycemic control with significant improvements in β-cell function and insulin sensitivity.