Pharmacogenomics of Thiazolidinediones (PPAR)

• Characterize the variability in response to thiazolidinediones (TZDs) at the physiological, cellular and molecular levels. [ Time Frame: 12 to 24 weeks ] [ Designated as safety issue: No ]
  The outcome will be measured for each subject at the end of their participation (12 to 24 weeks). However, analysis of these outcomes will occur at the completion of all subject participation.
  
  

• Define genes whose regulation correlates to TZD response. [ Time Frame: 12 to 24 weeks ] [ Designated as safety issue: No ]
  The outcome will be measured for each subject at the end of their participation (12 to 24 weeks). However, analysis of these outcomes will occur at the completion of all subject participation.
  
  
• Identify the SNPs and haplotypes in candidate genes that influence TZD response. [ Time Frame: 12 to 24 weeks ] [ Designated as safety issue: No ]
  The outcome will be measured for each subject at the end of their participation (12 to 24 weeks). However, analysis of these outcomes will occur at the completion of all subject participation.
  
  

In phase I, subjects who are eligible based on height and weight and general health information will sign informed consent. In phase II, subjects will be screened to ensure that they fit the inclusion/exclusion criteria, including an oral glucose tolerance test. Other blood tests will be performed to check complete blood count, lipids, liver functions and electrolytes.

Qualifying volunteers will enter phase III, which will consist of outpatient radioimaging and body composition, metabolic testing (intravenous glucose tolerance test), and tissue biopsies. Blood will also be drawn for genetic testing and for microarray studies of leukocytes. Written medication information and instructions for pioglitazone, discharge instructions and satisfaction surveys following the tissue biopsy procedures will be given to subjects during the study. During phase IV, subjects will begin pioglitazone therapy. Every 4 weeks throughout the drug intervention, glycemic control, lipoprotein profile, and weight will be monitored. After 12 weeks of pioglitazone therapy, the X-ray and MR measurements of body composition, the biopsies and the metabolic tests performed during phase III will be repeated (phase V), and blood will be drawn for microarray studies of leukocytes.

Thereafter, subjects will have the option to be enrolled in a 10 week, behavioral weight loss program (phase VI). Following the 10-week weight loss program, a few outcome measurements will be repeated (phase VII).

Throughout the study, Women of Child Bearing Potential (WCBP) will have HCG urine pregnancy tests. Pregnancy tests will only be performed on Women of childbearing potential, meaning women who are pre-menopausal and who have not had surgical sterilization. Women who have not had a hysterectomy or tubal ligation at least six months prior to signing informed consent or have been postmenopausal for at least one year, will be instructed to practice one of the following methods of birth control throughout the study: oral, transdermal, or implantable hormonal contraceptives, intrauterine device, diaphragm plus spermicide, condom plus spermicide, or abstinence. Pioglitazone may reduce the effectiveness of some hormonal types of contraceptives. Women using hormonal methods of birth control will be advised to use a barrier method as well. Female subjects are informed to notify the investigators immediately if they think they might have become pregnant during the study.

Participants who are eligible have 10 visits over an approximate 15-week period. Participants can choose to participate in an optional weight management program for an additional 10 weeks after treatment and before their final visit.