Leptin is famously known as the satisfaction hormone. It's what triggers that sensation of fullness you get after you've eaten. Leptin comes from fat and, when released, it binds with receptors all over your body, but especially in your brain. In addition to playing a role in weight control, leptin also impacts the cells that release insulin. A lack of leptin in the pancreas sets the stage for insulin resistance and diabetes.
Leptin's Ascent
Dr. Jeffrey Friedman and his colleagues from Rockefeller University discovered leptin in the mid-1990s through research with mice. They first saw leptin as a hormone produced by fat cells that seemed to play a role in weight management. With proper levels of leptin, mice maintained their weight, but without it they would eat with abandon. Health authorities and media announced that the discovery would help slash obesity rates, but early trials haven't been so successful. Some people are resistant to the effects of leptin, and leptin's actions in the body are far more complex than previously thought. Today, researchers know leptin plays a role not only in weight management, but also fertility and reproduction, heart health, immune function and the way other hormones work -- especially insulin. The latter makes leptin of interest to those fighting diabetes.
Leptin and Insulin
Researchers from Harvard University's Joslin Diabetes Center first detected the link between leptin and diabetes in 2007. Leptin, they said, provides a check on your insulin level to keep it from getting too high. It does that by affecting insulin secretion from the pancreas. The researchers knew from an early experiment that when they knocked out leptin receptors in the pancreas, more insulin was released and the mice in their experiment showed greater glucose tolerance. What the researchers were trying to resolve, however, is the common problem of obese people developing diabetes, despite having high levels of insulin and leptin. Insulin's job is to help remove blood sugar, and leptin is supposed to control your weight.
Leptin and the Development of Diabetes
In a second part of the 2007 experiment, Joslin researchers fed the genetically engineered group of mice and a control group a high-fat diet. Both sets of mice became obese. However, only those lacking leptin receptors in the pancreas developed insulin resistance, a precursor to diabetes. The researchers concluded that, in the face of obesity, the lack of leptin signaling in the pancreas leads to poor development of the cells that produce insulin, which leads to glucose intolerance and ultimately diabetes. Scientists have been investigating diabetes treatment models that manipulate insulin and leptin, and the results could have implications for both type 1 and type 2 diabetes.
Metreleptin
As of 2011, you can't buy leptin to help treat diabetes and obesity, but that could change. In Dec. 2010, Amylin Pharmaceuticals submitted an application to the FDA for metreleptin to treat diabetics with a metabolic disorder called lipodystrophy. Metreleptin is the synthesized version of human leptin. Lipodystrophy causes abnormalities in the way fat tissue is distributed throughout your body. Commonly, it involves serious fat accumulation in the belly, breasts and back of the neck. In June 2011, Amylin representatives announced results from clinical trials of metreleptin. They told attendees of the 93rd Annual Meeting and Expo of the the Endocrine Society that metreleptin improved diabetics' A1C levels, an index of blood sugar levels over the course of three months. In addition, it improved their triglyceride levels. Amlyn also reported that participants who were on diabetes medications, including insulin, were able to stop or reduce their diabetes treatment.
References
- Rockefeller University: Leptin
- Amylin Pharmaceuticals, Inc.; Amylin Submits Clinical and Nonclinical Sections of Rolling Biologics License Application for Metreleptin to Treat Rare Forms of Lipodystrophy; December 2010
- Joslin Diabetes Center; Joslin Researchers Uncover Potential Role of Leptin in Diabetes; October 2007
- PR Newswire; Study Finds Treatment with Metreleptin Improved Diabetes and Lipid Control in Patients with Partial Lipodystrophy; June 2011
- "Expert Opinion on Biological Therapy"; Leptin Gene Therapy in the Fight Against Diabetes; Yuqing Wang et al.; October 2010
