Inclusion Criteria:  Two groups (n=10 each) of subjects will be recruited to complete this study: 1) trans men between 18 and 35 years; 2) cisgender women between 18 and 35 years (Controls). They will have a body mass index (BMI) 18-30 kg·m-2. Our subjects will be matched on BMI and IR, using hemoglobin A1c and Homeostatic Model Assessment of Insulin Resistance technique (HOMA-IR) in order to isolate testosterone effects from other co-morbidities that may impact BP, sympathetic activity or endothelial function. Subjects will have HbA1c of 4-5.9% and a HOMA-IR of 0.5-1.4 to be included in the study. Subjects who smoke, have diabetes, or BP>140/90 will be excluded. Subjects will not be taking medications during the study, including any insulin sensitizing or CV medications.  Exclusion Criteria:  Subjects with the following histories or conditions will be excluded from the study:  Gynecologic: a. current or past estrogen-dependent neoplasia, b. unexplained vaginal bleeding, c. history of uterine fibroids, d. current pregnancy, e. known or suspected breast or uterine cancer, f. partial or complete hysterectomy.  Cardiac: a. myocardial infarction, ventricular tachycardia or fibrillation, b. angina, c. valvular disease (mitral insufficiency or stenosis, aortic insufficiency or stenosis), d. congestive heart failure, orthopnea, paroxysmal nocturnal dyspnea, e. current arrhythmias, f. prosthetic valves.  Pulmonary: a. current cigarette smokers, or pipe or cigar smokers, b. chronic obstructive pulmonary disease, c. adult asthma, d. dyspnea on exertion, e. current bronchitis, pneumonia, or tuberculosis, f. lung carcinoma, g. pulmonary embolus, h. deep vein thrombosis.  Vascular: a. claudications or history of peripheral vascular disease, b. abdominal or thoracic aortic aneurysm, or repair of same, c. cerebral aneurysm, vascular malformations, d. hypertension, systolic or diastolic, or strong family history of hypertension.  Gastrointestinal: a. GI malignancy, b. hepatitis or other liver disease, current, c. splenomegaly from any cause, d. Cholecystitis, e. current diverticulosis or diverticulitis, inflammatory bowel disease, ulcerative colitis, Crohn's disease, f. previous gastrointestinal surgery.  Infectious Disease: any ongoing intercurrent infection. Hematologic/Oncologic: a. receiving chemotherapy or radiation therapy, b. any metastatic malignancy, c. anemia (hematocrit < 35), d. thrombocytopenia or thrombocytosis, e. neutropenia, f. hematologic malignancy, g. bleeding dyscrasia.  Neurologic: a. history of cerebral vascular accident with any neurologic sequels, b. uncontrolled seizures (e.g., more than 1 seizure/year), c. transient ischemic attacks, d. dementia, e. neurologic conditions producing dyscoordination, peripheral neuropathy, or myopathy.  Endocrine: a. diabetes mellitus, b. any untreated endocrinopathy. Renal: a. chronic renal diseases, b. any history of renal disease or impairment, c. current urinary tract infection.  Musculoskeletal: a. inflammatory arthritis history (e.g., rheumatoid, psoriatic, Reiters), b. any history of pathologic fractures, including vertebral compression fractures.  Pharmacologic: a. any illegal drug use, b. alcohol use greater than an average of 4 oz/day over 30 days, c. coumadin or heparin use.