Getting too much or too little sleep could make more people at high risk of prediabetes more likely to develop type 2 diabetes, scientists suggest.
The link between sleep and type 2 diabetes is well established: various sleep disturbances, such as jet lag or night shift work can affect blood glucose control in type 2 diabetes.
In this new trial, US researchers investigated how poor sleep patterns affected people at risk of prediabetes, which can precede type 2 diabetes.
The University of Chicago study involved nearly 1,000 overweight or obese adults aged between 20 and 65. They participated in blood tests and kept a sleep diary.
The data showed that those who had less than five hours of sleep a night on average, or more than eight hours, had poorer blood glucose control over three months. These findings were consistent irrespective of whether participants had type 2 diabetes or prediabetes.
The trial’s findings also suggest that having too much sleep also has a similar impact as poorer blood glucose control was observed in those sleeping for more than eight hours a night.
Those who regularly experienced seven to eight hours a night seemed to have better glucose control. The way the study was run means we that the researchers were able to find associations related to sleep time, however, the study cannot show conclusively that sleep time is necessarily a causal factor for poorer blood glucose.
Lead author Dr Babak Mokhlesi of the University of Chicago said: “In the past, the general wisdom was that short sleep duration is bad for you but here we also found that maybe too long of a sleep duration is also not good for you.”
At the moment, the research team are not clear on why sleeping for longer periods of time might increase the risk of type 2 diabetes.
The findings have been published in the Diabetes Care journal.