42 assessed diabetes risk in healthy lean volunteers via an intravenous glucose tolerance test following either short sleep (five nights of 4 h/night) or the rested condition (five nights of 12 h/night).42 Both insulin sensitivity and disposition index, a marker of diabetes risk, were significantly decreased following short sleep in healthy volunteers. These findings have been replicated in subsequent studies with varying degrees of sleep time and quality.43, 44, 45, 46, 47, 48. This evidence concerns the gene INS and diabetes mellitus.