Rising environmental temperatures have been linked to an increased risk of obesity and type 2 diabetes in a new Dutch study.

Scientists from Maastricht University Medical Centre, the Netherlands, believe a one degree centigrade rise in outdoor temperature could lead to 100,000 new cases of type 2 diabetes in the US each year.

“This emphasizes the importance of future research into the effects of environmental temperature on glucose metabolism and the onset of diabetes, especially in view of the global rise in temperatures,” said Lisanne L Blauw, a PhD student at Leiden University Medical Center.

Blauw and colleagues believe this association is because of brown fat, which generates heat in response to cold and consequently burns fat. When environmental temperature rises, less brown fat is needed to keep warm, leading to weight gain and insulin resistance.

In their study, published in the BMJ Open Diabetes Research and Care, they recommend lowering thermostats to between 15 C and 17 C for a few hours each day.

They say that this will help lessen the risk of weight gain, particularly for those who spent more time indoors and whose bodies do not naturally burn calories to keep warm.

But Dr Louise Brown from University College London, who was not involved in the study, has questioned the significance of these findings.

“Overall, the uncovering of this association is interesting but I do not feel that is of great help in our fight against the increasing global incidence of diabetes, unless they are suggesting that we all move to colder climates,” she said.

“If they have stumbled across a useful pointer that leads to appropriate metabolic research on the role of brown fat in the development of diabetes then great, but their claims are too strong at this stage.”