Shorting sleep regularly or sleeping out of phase with the day-night cycles (typical of shift work) seems to produce physiological changes that predispose people to type 2 diabetes. Researchers confrimed this when 21 participants lived in a sleep laboratory with no contact with the outside world for 6 weeks. Fortunately, these changes reverted during the 9 day recovery period.
PositiveTip: Regularity in sleep can strengthen your resistance to diabetes (and probably other diseases, too).