Lack of sleep may raise the risk of diabetes - even in healthy people, a study has warned.
Researchers found getting too little shut-eye for just three nights reduces the ability of insulin to regulate blood sugars.
US researchers suggest insufficient sleep may be playing a role in the current epidemic of obesity and type 2 diabetes.
Something as simple as getting enough sleep could help reverse those trends, they claim.
The study, from Chicago University, is the first to examine the impact of sleep loss on 24-hour fatty acid levels in the blood.
They found sleep restriction can elevate levels of free fatty acids in the blood by up to a third, leading to temporary pre-diabetic conditions in healthy young men.
Assistant professor of medicine, Dr Esra Tasali, said: 'At the population level, multiple studies have reported connections between restricted sleep, weight gain, and type 2 diabetes.
'Experimental laboratory studies, like ours, help us unravel the mechanisms that may be responsible.'
A study last year found shift work raises the risk of developing type 2 diabetes by more than a third.
This is possibly because disruption to the body clock affects hormone levels which may lead to insulin resistance and diabetes.
In the latest study, researchers found after three nights of getting only four hours of sleep, blood levels of fatty acids, which usually peak and then recede overnight, remained high for several hours.
As long as fatty acid levels remained high, the ability of insulin to regulate blood sugars was reduced.
The study, published online in Diabetologia, the journal of the European Association for the Study of Diabetes, involved 19 healthy men aged between 18 and 30.
First, they got a full night's rest of 8.5 hours in bed and an average 7.8 hours sleep during four consecutive nights.
Then, four weeks on, they got just 4.5 hours in bed with an average 4.3 hours asleep for four consecutive nights.
Each man's sleep was carefully monitored, diet was strictly controlled and blood samples were collected at 15 or 30 minute intervals for 24 hours, starting on the evening of the third night of each study.
The researchers measured blood levels of free fatty acids and growth hormone, glucose and insulin, and the stress hormones noradrenaline and cortisol.
After four nights in each sleep condition, a glucose-tolerance test was performed.
Too little sleep resulted in a 15 to 30 per cent increase in late night and early morning fatty acid levels.
The nocturnal elevation of fatty acids (from about 4 a.m. to 6 a.m.) correlated with an increase in insulin resistance - a hallmark of pre-diabetes - that persisted for a nearly five hours.
Cutting back on sleep prolonged night time growth hormone secretion and led to an increase in the stress hormone noradrenaline in the blood, both of which contributed to the increase in fatty acid levels.
Although glucose levels were unchanged, the ability of available insulin to regulate blood glucose levels decreased by about 23 per cent after a short sleep, ‘suggesting an insulin-resistant state.’
Study leader Dr Josiane Broussard said: 'Curtailed sleep produced marked changes in the secretion of growth hormone and levels of noradrenaline - which can increase circulating fatty acids.
‘The result was a significant loss of the benefits of insulin. This crucial hormone was less able to do its job.
'Insulin action in these healthy young men resembled what we typically see in early stages of diabetes.’
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