Dolphins have diabetes off switch

A study in dolphins has revealed genetic clues that could help medical researchers to treat type 2 diabetes.

Scientists from the US National Marine Mammal Foundation said that bottlenose dolphins are resistant to insulin – just like people with diabetes.

But in dolphins, they say, this resistance is switched on and off.

The researchers presented the findings at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Diego.

They hope to collaborate with diabetes researchers to see if they can find and possibly even control an equivalent human “off switch”.

The team, based in San Diego, took blood samples from trained dolphins that “snack” continuously during the day and fast overnight.

“The overnight changes in their blood chemistry match the changes in diabetic humans,” explained Stephanie Venn-Watson, director of veterinary medicine at the foundation.

This means that insulin – the hormone that reduces the level of glucose in the blood – has no effect on the dolphins when they fast.

Big brains

In the morning, when they have their breakfast, they simply switch back into a non-fasting state, said Dr Venn-Watson. In diabetic people, chronic insulin resistance means having to carefully control blood glucose, usually with a diet low in sugar, to avoid a variety of medical complications.

But in dolphins, the resistance appears to be advantageous. Dr Venn-Watson explained that the mammals may have evolved this fasting-feeding switch to cope with a high-protein, low-carbohydrate diet of fish.

“Bottlenose dolphins have large brains that need sugar,” Dr Venn-Watson explained. Since their diet is very low in sugar, “it works to their advantage to have a condition that keeps blood sugar in the body