Impact of Actos (Pioglitazone) on Muscle Glucose Transporters in Type 2 Diabetes

Twelve subjects with type 2 diabetes, with fair control on oral medication, will be recruited to participate in a randomized, double-blind, placebo-controlled study of the impact on muscle glucose transporter expression of the addition of the insulin-sensitizing agent, pioglitizone (Takeda Pharmaceuticals). Therapy with the active drug will be at 30 mg daily. The other oral medications will be adjusted downward if hypoglycemia occurs. Glycemic control will be monitored by at least twice daily home blood glucose monitoring, weekly telephone contacts, and follow-up visits to the ETSU/VAMC Clinical Research Unit (CRU) every two weeks. During the eight weeks of therapy, subjects will be instructed to maintain their weight and keep their dietary and exercise regimens unchanged. Muscle biopsies will be obtained before and at the end of eight weeks of therapy. Specimens will be assayed for GLUT1, GLUT3, GLUT4, GLUT5, GLUT8, GLUT11, and GLUT12 mRNA and protein content and the subcellular distribution of these proteins as described below. Peroxisome proliferator-activated receptor gamma (PPARgamma), a member of the ligand-activated nuclear hormone receptor superfamily (14), will be quantified in these specimens by immunoblot as described below. This study design involving a randomized, double-blinded, placebo-controlled treatment regimen is needed to control for confounding variables causing changes in glucose transporter expression that may be erroneously attributed to the drug. These potential variables include close contact with the diabetes management team resulting in improved compliance with diet, exercise, medication, and monitoring and thus better glycemic control, weight loss, or improved fitness.