Editing Proinsulin (section)

=== [[Diabetes mellitus|Diabetes Mellitus]] ===
Increased levels of proinsulin in the [[circulatory system]] relative to mature insulin concentrations can indicate impending [[insulin resistance]] and the development of [[type 2 diabetes]].<ref>{{cite journal | vauthors = Mykkänen L, Haffner SM, Hales CN, Rönnemaa T, Laakso M | title = The relation of proinsulin, insulin, and proinsulin-to-insulin ratio to insulin sensitivity and acute insulin response in normoglycemic subjects | journal = Diabetes | volume = 46 | issue = 12 | pages = 1990–5 | date = December 1997 | pmid = 9392485 | doi = 10.2337/diab.46.12.1990 | s2cid = 44874023 }}</ref> Additional problems with proinsulin that can lead to diabetes include mutations in the number of cysteines present, which could affect correct folding.<ref name="Weiss_2009"/> If the mutation causes only a mild change it could simply stress the endoplasmic reticulum’s ability to properly fold the protein.<ref name="Weiss_2009" /> This stress, after a while, would lead to a decrease in the number of [[Beta cell|β-cells]] producing mature insulin, and would then lead to diabetes mellitus.<ref name="Weiss_2009" />