In this protocol, to be carried out at both the NIH and the University of Texas in Dallas, we test the hypotheses that leptin can be safely administered to patients with lipoatrophic diabetes and they will benefit from treatment with A-100 (recombinant form of human leptin provided by Amgen). We will study patients with lipoatrophy, low leptin levels, and at least one of the following metabolic abnormalities: severe insulin resistance, diabetes, and/or hypertriglyceridemia.