You may be eligible to take part in this study if you
- are 18-65 years old;
- have been medically diagnosed with Type 2 diabetes and currently taking metformin (500-2550 mg daily), but otherwise healthy as determined by the study physician;
- have an HbA1c < 8% as determined by laboratory analysis on initial screening;
- are not taking any medications, dietary/herbal supplements, or citrus juices that can interfere with your ability to eliminate the study drugs and goldenseal;
- are willing to abstain from consuming alcohol, caffeinated beverages or other caffeine-containing products the evening before and the morning of the first day of each study arm;
- are female and are willing to use an acceptable method of contraception that does not include oral contraceptive pills or patches (such as abstinence, copper IUD, condom); and/or
- have the time to participate.