Just three nights of bad sleep is enough to dramatically reduce the body’s ability to process glucose and raise the risk of diabetes, a study has found.

Suppressing deep sleep for three nights in a row decreased the glucose tolerance of young, healthy adults as much as if they had gained eight to 13 kilos, researchers at the University of Chicago’s medical school found.

And while it is possible that the body’s ability to process glucose would adjust to chronic sleep deprivation, it is likely that poor sleep patterns in the elderly and obese play a role in the development of diabetes, the authors concluded.