Statins are highly efficacious lipid modifying agents that reduce the risk for cardiovascular (CV) events in both primary and secondary prevention settings. However, statins affect molecular mechanisms which adversely impact on insulin sensitivity and β-cell function, thereby increasing risk for new onset diabetes mellitus (NOD). Defining the mechanisms involved is the focus of considerable current investigation. The statins reduce the risk for CV events in normoglycemic patients as well as in those with diabetes mellitus (DM) and their benefits outweigh the risk of inducing NOD. We review the clinical evidence for NOD with statin treatment, as well as the potential mechanisms involved. Our literature search was based on PubMed and Scopus listings. Further large studies are needed to elucidate both the association between NOD and statin use and the underlying mechanisms.