S&T Watch-33: "Treating Type-I Diabetes without Insulin"

Type-I diabetes, also known as juvenile diabetes, is an autoimmune disease in which the immune system attacks and kills insulin-producing cells in the pancreas. About 10% of people with diabetes have this form of the disease. The only treatment for Type-I diabetes hitherto has been intramuscular administration of insulin. But soon a new line of treatment may be available using the hormone leptin. Recent studies with rodents suggest that a little extra production of leptin through gene therapy can bring terminally ill rodents with Type-I diabetes back from the brink of death (Proceedings of the National Academy of Sciences, 25 August 2008).

Leptin is a hormone made by fat cells and plays a key role in regulating energy intake and energy expenditure. It also helps control eating behaviour. A new study suggests that it can also treat diabetes , the first demonstration that the disease can be treated without replacing insulin.

Researchers at the University of Texas Southwestern Medical Centre at Dallas, USA, used adenovirus to insert extra copies of the leptin gene in diabetic mice and rats. The rodents recovered from the most severe side-effects of diabetes, even though they were not given insulin. The terminally ill diabetic rodents making extra leptin recovered with no trace in their bodies, and leptin produced more sustained health improvements than insulin injections did. These included normalising blood sugar for up to 80 days without insulin, stopping the overproduction of glucose by the liver, improving sugar use in the muscles, and allowing the animals to gain weight. The gene therapy also corrected ketosis - a process characteristic of diabetes in which the body burns fat, producing sweet-smelling chemicals called ketones.

According to the researchers, excess leptin probably blocks the action of glucagon, a hormone that works as a counterpoint to insulin, which helps cells use glucose for energy. Glucagon signals the liver to produce glucose from fats and other non-carbohydrate sources. In diabetics, high glucagon levels just raise blood sugar levels even higher and lead to other side-effects.

The researchers are not sure whether injections of leptin will work as well as making extra leptin through gene therapy does. But it is known that persons given injections of leptin for other reasons do show some improvement in blood sugar levels.

Courtesy: 'DREAM 2047', October 2008 ("Recent Development in Science and Technology" by Biman Basu - Email: bimanbasu@gmail.com).

Grateful thanks to Mr.Biman Basu and Dream 2047.