Is the human adipose tissue responsible for diabetes?

The functions and the distribution of adipose tissue in humans is pivotal for who gets diabetes and who does not

Extensive overweight (obesity / adiposity) strongly increases the risk to develop diabetes. Thus, the growing number of adipose women and men also mean ever more diabetics. However, about 15 percent of the obese individuals have a healthy metabolism. Scientists have found out that the functions and the distribution of adipose tissue in humans is pivotal for who gets diabetes and who does not. The Integrated Research and Treatment Center (IFB) AdiposityDiseases in Leipzig examines the so far little-known processes in adipose tissue, which are responsible for diabetes and further diseases associated with obesity. On the occasion of this year’s World-Diabetes-Day (Nov. 14, 2013) the IFB gives an insight into its adipose tissue research.

Round butt better than round belly

“Especially abdominal obesity increases the risk for diabetes and cardiovascular diseases”, explains IFB scientist Prof. Matthias Blüher. Besides the abdominal (visceral) fat accumulation, there are increased fat depositions in the liver, pancreas, and muscles. This kind of fat distribution is associated with a decreasing effectiveness of insulin in somatic cells. In this way an insulin resistance is developing which eventually leads to diabetes.

Pathogenic processes in the adipose tissue

“Particularly in the visceral adipose tissue dysfunctions in the fat cells and in the cellular structure can be found. These dysfunctions are finally pathogenic”, says Blüher. Researchers could detect enlarged fat cells, inflammatory markers and a dysfunctional secretion of adipose hormones (adipokines) in obese patients. The deficient supply with blood and oxygen may be one of the reasons for these dysfunctions in adipose tissue.

Especially the inflammatory processes in the visceral adipose tissue aggravate insulin resistance, arteriosclerosis, and fatty liver. These processes lead to a deluge with macrophages, immune cells that normally fight germs. IFB scientists could proof that high levels of the hormone progranulin in the blood are an indicator for these inflammatory processes. By measuring progranulin levels high risk patients could be detected and treated at an earlier stage.

Hormones of the adipose tissue

The adipose tissue produces a series of protein hormones (adipokines), which are engaged in metabolism and immune defense. They play a crucial role in the regulation of insulin sensitivity, appetite and satiety, of energy metabolism as well as the body’s inflammatory reactions.

Thus, the adipose tissue has to be seen as part of the human immune and hormonal system. The adipokine leptin for instance influences metabolism, energy consumption, and lowers hunger. Adiponektin positively aims at glucose metabolism and seems to be anti-inflammatory. In obesity the secretion of these hormones can however be affected. This promotes metabolic and cardiovascular diseases.

Can adipose tissue provide a new diabetes therapy?

Researchers in the field of adipose tissue assume the adipkine vaspin to be a possible basis for a new remedy, since animal tests have shown its blood suger lowering effect. Dr. John Heiker from the Institute of Bio-Chemistry in Leipzig, a co-opertion partner of the IFB, decoded vaspin’s mode of action: It improves the glucose metabolism in insulin resistance by inhibiting an enzyme (protease), which degrades insulin. Heiker received the notable research prize of the Max-Bergmann-Group for this scientific work.

“The research of adipose tissue opens up many opportunities. So far, there are no pharmacological therapeutic approaches aiming at the dysfunctions of adipose tissue. With Germany’s largest adipose tissue bank in Leipzig, sponsored by the federal research ministry, we are at an advantage in this field of research”, underlines Prof. Michael Stumvoll, scientific head of the IFB AdiposityDiseases.

Doris Gabel

Keywords: IFB-research, fat tissue & BMI, causes of obesity