When volunteers entered a stage of sleep called deep non-rapid eye movement (NREM), also known as slow-wave sleep (SWS), researchers made noise, but not enough to wake them. After three days, the participants' ability to regulate blood glucose declined by 25%.
This impaired glucose tolerance occurred even though the participants slept for 8.5 consecutive hours. It was the quality of their sleep, not the length, that determined their ability to manage blood glucose.
The research appeared in an online edition of the Proceedings of the National Academy of Sciences (PNAS) this month:
Slow-Wave Sleep And The Risk Of Type 2 Diabetes In Humans
Some news summaries:
Lack Of Deep Sleep May Increase Risk Of Type 2 Diabetes (Science Daily)
Sleep Disruptions May Up Diabetes Risk (Yahoo)