Insulin action in the brain: regulation of glucose metabolism demonstrated for the first time directly in humans

Selective insulin action in certain brain areas improves glucose metabolism throughout the body. This is a finding of a study by scientists from the Institute of Diabetes Research and Metabolic Diseases of Helmholtz Zentrum München at the University of Tübingen, published in the journal ‘Diabetes’.

Source: fotolia

In this study researchers administered insulin in the form of a nasal spray to healthy young men. By means of this method, insulin is taken up through the nasal passages and transported directly to the brain. Before and after the intranasal application of insulin, the glucose metabolism and the insulin action in the entire body were measured using the hyperinsulinemic-euglycemic clamp technique.



It was found that after the intranasal application of insulin, glucose uptake into the body improved. The researchers also repeated the experiments in obese men, but they showed no improvement in glucose uptake into the cells of the body; this test group showed resistance to insulin action in the brain.





Insulin activates the metabolic control center of the brain

The brains of the study participants were assessed by magnetic resonance imaging before and after the administration of the nasal insulin spray. The assessment showed that the change in the activation of the hypothalamus by insulin correlates to the improvement of the glucose uptake into the body cells. The hypothalamus is known as the control center of the metabolism. Furthermore, the activity of the autonomic nervous system was measured after the intranasal application of insulin. This activity changed most in those study participants that showed the strongest improvement of glucose uptake into the body cells, thus demonstrating that the autonomic nervous system transmits the insulin signal in the brain to the body.



For the first time it could be demonstrated in humans that insulin action in the brain improves glucose metabolism. This mechanism probably plays an important role postprandially (after eating), when insulin levels rise to facilitate glucose uptake in the body. The effect could only be shown in lean study participants. By contrast, obese study participants were resistant to insulin in the brain. The study shows that changed reactions in the brain are involved in the development of whole-body insulin resistance, a key factor of type 2 diabetes.



To press release by the German Center for Diabetes Research





Further Information



Original publication:

Heni M. et al. (2014). Central insulin administration improves whole-body insulin sensitivity via hypothalamus and parasympathetic outputs in men, Diabetes, doi: 10.2337/db14-0477.



Link to publication





Helmholtz Zentrum München, as German Research Center for Environmental Health, pursues the goal of developing personalized medical approaches for the diagnosis, treatment and prevention of major widespread diseases such as diabetes mellitus and lung diseases. To achieve this, it investigates the interaction of genetics, environmental factors and lifestyle. The head office of the Center is located in Neuherberg in the north of Munich. Helmholtz Zentrum München has a staff of about 2,200 people and is a member of the Helmholtz Association, a community of 18 scientific-technical and medical-biological research centers with a total of about 34,000 staff members. www.helmholtz-muenchen.de



The German Center for Diabetes Research e.V. brings together experts in the field of diabetes research and combines basic research, epidemiology and clinical applications. The members of the association are the German Diabetes Center (DDZ) in Düsseldorf, the German Institute of Human Nutrition (DifE) in Potsdam-Rehbrücke, the Helmholtz Zentrum München – the German Research Center for Environmental Health, the Paul Langerhans Institutes of the Carl Gustav Carus University Hospital in Dresden and the Eberhard Karl University of Tübingen as well as the Gottfried Wilhelm Leibniz Research Association and the Helmholtz Association of German Research Centers. The aim of the DZD is to find answers to unsolved questions in diabetes research by adopting a novel, integrative approach and to make a significant contribution towards improving the prevention, diagnosis and treatment of diabetes mellitus.





