Background We examined whether primary prevention with statins and high adherence to statins reduce the associated risk of cardiovascular events or death in a low-risk population with type 2 diabetes mellitus (T2D). Methods and Results Using Danish nationwide registers, we included patients with new-onset T2D, aged 40 to 89 years, between 2005 and 2011, who were alive 18 months following the T2D diagnosis (index date). In patients who purchased statins within 6 months following T2D diagnosis, we calculated the proportion of days covered (PDC) within 1 year after the initial 6-month period. We studied the combined end point of myocardial infarction, stroke, or all-cause mortality, whichever came first, with Cox regression. Reported were standardized 5-year risk differences for fixed comorbidity distribution according to statin treatment history, stratified by sex and age. Among 77 170 patients, 42 975 (56%) were treated with statins, of whom 31 061 (72%) had a PDC >= 80%. In men aged 70 to 79 years who were treated with statins, the standardized 5-year risk was 22.9% (95% CI, 21.5%-24.3%), whereas the risk was 29.1% (95% CI, 27.4%-30.7%) in men not treated, resulting in a significant risk reduction of 6.2% (95% CI, 4.0%-8.4%), P= 80%; PDC