Night work provokes diabetes and obesity

Overweight and type II diabetes through night work

22/02/2013

Obesity and type II diabetes are among the typical diseases of prosperity in western industrialized countries. What is certain is that an oversupply of unhealthy foods is responsible for this. US researchers have now found that certain ways of working, such as shiftwork and lack of sleep, favor the metabolic disease of diabetes. Because who works at night and in addition to too little sleep, brings his inner clock out of balance. „In addition, the insulin budget is disturbed“, as the researchers at Vanderbilt University in Nashville summarize.

In addition to a permanently wrong diet, too little exercise and family bias, US scientists have discovered a new possible cause of diabetes and obesity. If workers in shifts have to work at night and thus sleep too little, the patient's internal clock and thus also the insulin balance are disturbed. „For the weight, it is not only important what is eaten, but also when“, the scientists report in the journal "Current Biology". A mouse experiment showed that the effects of the hormone insulin change during the day. Just that hormone has a significant influence on the blood sugar level.

Disruption of daily rhythms provokes insulin resistance
However, if the internal clock is continually disturbed by various daily rhythms, shift workers are likely to develop insulin resistance over time and become more susceptible to overweight and obesity. At any rate, this was shown during the laboratory experiment with mice. „The results of the investigations can be of great importance in the treatment of diabetes and obesity“, explain the study authors. The biological clock is currently not included in treatment options for metabolic disorders.

Earlier studies had shown that people who suffer from sleep disorders, for example because they have jet lag or are constantly working at night, often suffer as a result of metabolic disorders. In addition, further research has shown that special types of so-called clock genes, which are responsible for controlling the internal clock, are associated with diabetes, obesity and hypertension (high blood pressure).

„Not enough research was done on the insulin action, which is altered by the rhythm of the hormone“, Study Director Shu-qun Shi reports. With the current study, researchers were able to show that nocturnal mice were most resistant to insulin by day. As a result, blood sugar levels were highest among rodents at that time because less sugar is being transported out of the blood. In contrast, the insulin effect increases at night, because then the animals are active and the metabolism is stimulated. This also reduces the blood sugar level. „In genetically modified animals, where the internal clock has been intentionally disturbed, they show insulin resistance by day and by night“, as the authors write.

In the further experimental setup mice were exposed to a permanent light. This condition inevitably destroys the biological clock. Thus, the insulin household also fluctuates. In addition, when the animals were given a high-fat diet, those animals stored more fat than others without permanent light.

Study allows new therapeutic approaches
Although it was „normal that the insulin effect fluctuates during the day“, the scientists write, that is natural after all, because „the environment also behaves rhythmically“. Living beings who can adapt to just those fluctuations can adapt their behavior, their metabolism and their gene activities to the external circumstances. These creatures have much better chances of survival because they can keep their organic functions constant.

Coordinated diets where the meal is regulated by time, „can not stop or reverse the overweight and diabetes epidemic, but it could help fight it“, explained the researcher Carl Johnson. In order to develop the knowledge for therapeutic purposes, further research in this area will take place. (Sb)

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Picture: me