Resistance to insulin can lead to poor blood glucose control (blood sugar levels that are higher than normal). In this research study we will apply advanced imaging technology, called Positron Emission Tomography (PET), in combination with Magnetic Resonance Imaging (MRI), to study how insulin works on sugar in your body's muscle and fat tissue. We recently demonstrated that young, non-obese African American women have a separate form of lower insulin sensitivity (a major risk factor for development of diabetes) compared to Caucasian women, with lower tissue glucose uptake, but similar insulin sensitivity in the liver.