Background: \- Generalized lipodystrophy can cause high blood fat levels and resistance to insulin. This can lead to health problems including diabetes. Researchers have found that the drug metreleptin improves health in people with this disease.

Objective: \- To test the safety and effectiveness of metreleptin.

Eligibility: * People ages 6 months and older with generalized lipodystrophy who: * have received metreleptin through NIH studies AND * cannot get it through approved or compassionate use mechanisms in their home country.

Design: * Participants will come to NIH approximately every 6 months during year one, then every 1 2 years. Financial assistance may be available for travel within the U.S. * At visits, participants will get a supply of metreleptin to take home for daily injections. They will have: * plastic catheter placed in an arm vein. * blood tests, urine collection, and physical exam. * oral glucose tolerance test, drinking a sweet liquid. * ultrasound of the heart, liver, uterus, and ovaries. A gel and a probe are placed on the skin and pictures are taken of the organs. * echocardiogram, which takes pictures of the heart with sound waves. * Resting Metabolic Rate taken. A plastic hood is worn over the head while the oxygen they breathe is measured. * Participants will have up to 3 DEXA scan x-rays per year. * Participants may have: * annual bone x-rays. * liver biopsies every few years. A needle will be inserted into the liver to obtain a small piece. Participants will sign a separate consent for this. * Participants must be seen regularly by their local doctors and have blood tests at least every 3 6 months at home.