Taking power naps during the day, which was previously thought to be beneficial, may in fact increase the risk of developing Type 2 diabetes, according to new research.

The study of 16,480 people in China found that those who napped even once a week were 26 per cent more likely to develop the disease than those who did not.

Several factors might be linked to this finding, the researchers suggest, such as an association between napping and reduced physical activity - people who nap are also probably taking less exercise.

Napping during the day could also disrupt night sleep. Shorter night sleeps have been found to be linked to increased risk of Type 2 diabetes.

The research, conducted by scientists from the University of Birmingham and from Guangzhou Hospital in China, will be presented at Diabetes UK's annual conference in Glasgow's SECC.

The researchers will tell delegates that waking up from napping also activates hormones and mechanisms in the body that stop insulin working effectively, and this could predispose people to Type 2 diabetes that can develop when the insulin the body makes does not work properly.

Iain Frame, director of research at Diabetes UK, said, "We already know that people who are overweight or obese, and therefore more at risk of developing Type 2 diabetes, can have problems sleeping. "This new research could be another step towards explaining the possible link between disturbed sleep patterns and Type 2 diabetes."

''However, in terms of being major risk factors for developing Type 2 diabetes, disturbed sleep or napping are likely to remain less significant than already established risk factors such as being overweight, being over the age of 40 or having a history of diabetes in the family," Frame added.

Diabetes is a serious condition that can lead to long-term complications such as heart disease, stroke, blindness, kidney failure and amputation. Short-term complications include hypoglycaemic episodes, which can lead to unconsciousness and hospitalisation if left untreated, and persistent high blood glucose levels that can be fatal if untreated.

Lead researcher Shahrad Taheri said, ''Our research provides us with an additional insight on the risk factors behind type 2 diabetes.''

A total of 2.25 million people in the UK are diagnosed with Type 2 diabetes, which is linked to unhealthy lifestyles and obesity, and another 500,000 are thought to be undiagnosed.