INS and type 2 diabetes mellitus: From the experimental data discussed, we can summarise as follows: in short-term, acute, laboratory and cross-sectional studies, disturbed or reduced sleep is associated with glucose intolerance, insulin resistance, reduced acute insulin response to glucose and a reduction in the disposition index, reduced peripheral insulin response and up- and down-regulation of the expression of genes involved in metabolic pathways, all predisposing factors to the development of type 2 diabetes.