Patients with lipodystrophy have low levels of a human hormone called leptin, which plays a key role in regulating the break-down of fats and sugars in the body. This leads to loss of fat from under the skin and its build-up in places such as the liver and muscles, as well as high levels of fat in the blood. It also results in insulin resistance (when the body is unable to recognise insulin, a hormone that helps regulate blood sugar levels).

The active substance in Myalepta, metreleptin, is similar to leptin. It replaces leptin and increases fat breakdown in the blood, muscles and liver, thereby correcting some abnormalities in patients with lipodystrophy, including insulin resistance. However, the medicine does not restore fat tissue under the skin.