Researchers continue to investigate the link between obesity and diabetes. Though scientists realize it is a major factor in the development of type 2 diabetes, exactly how the excess fat causes the disease is not clearly understood. The search for the link at the molecular level involves clinical research to not only find the connection, but also develop measures to combat these conditions.

One line of research involves examining the pathway that is responsible for a series of reactions within the body that lead to insulin resistance. Researchers have discovered that obesity leads to stress within a system of cellular membranes known as endoplasmic reticulum (ER). The stress in this system in turn causes the ER to suppress the insulin receptor signals, which leads to insulin resistance.

Other researchers have located a primary trigger for type 2 diabetes – a genetic “master switch” in the liver that is flipped on when people become obese. Once on, this switch creates low-level inflammation, which in turn disrupts the body’s ability to process insulin, resulting in the development of type 2 diabetes.

A hormone called resistin is also being studied as a potential link between obesity and diabetes. The hormone, discovered in mice, causes cells to be resistant to insulin. Too much of this hormone is believed to result in insulin resistance. In mice, limiting their resistin activity showed an improvement in their glucose (blood sugar) level and response to insulin.

Resistin, along with leptin and adiponectin, are signaling proteins released by fat cells. Leptin is released by fat cells after a meal, signaling the body to stop eating. Researchers have found that mice lacking the leptin gene were not receiving the signal and therefore becoming obese. However, in trials, leptin failed to combat obesity. This led researchers to conclude that additional factors must be at work in the development of obesity.

Too little of the hormone adiponectin may lead to insulin resistance. In mice models, scientists have found that drugs that lower resistin levels also increase adiponectin levels. At least in mice, adiponectin appears to help the muscles burn more energy and also reduce body weight. It is hoped that adiponectin will become a good target for new diabetes treatments in humans.

Scientists are continuing to identify genes implicated in obesity and diabetes, including the recently discovered ENPP1. Such discoveries may one day lead to treatments.

In recent years there has been growing interest into weight-loss surgery as a way to prevent or treat type 2 diabetes. Experts such as the American Diabetes Association describe type 2 diabetes as a chronic condition with no known cure, but some researchers have reported resolution of the disease in severely obese patients who underwent bariatric surgery. However, these procedures have risks and side effects, and the long-term health of such patients continues to be assessed.