DIAD study by Young et al. JAMA 09 

The potential of routine screening to alter treatment and consequently to prevent cardiac events is highly controversial.

While endorsed by some professional organizations, there is limited evidence on this topic.

Patients with type 2 diabetes represent probably the ideal candidates for such an empirical approach as diabetes has been considered a coronary artery disease (CAD) equivalent and in patients with type 2 diabetes cardiovascular disease is by far the leading cause of mortality and morbidity.

In the Detection of Ischemia in Asymptomatic Diabetics (DIAD) study, 1123 asymptomatic diabetic patients were randomized to be screened with adenosine-stress radionuclide myocardial perfusion imaging or no screening. The primary endpoint was the occurrence of death or nonfatal myocardial infarction at follow-up. The study failed to show any benefit in terms of the primary endpoint or for any secondary endpoints in the actively screened group as compared to conventional management with a cumulative composite of death or MI in the range of 3% in both groups after a median follow-up of 5 years.

Authors conclude by emphasizing that this is not a negative study, rather it conveys the positive message that diabetic patients have a fairly good outcome with state-of-art medications when managed in a conventional manner.

However, there a number of caveats which may merit attention before concluding that screening for CAD in this relatively high risk group is of no use, including that fact that a much higher event rate was originally expected, thus this study is technically largely underpowered, and secondly the fact that despite roughly 20% of screened patients was found to have a positive cardiac scan only a fraction of them underwent coronary angiography and subsequent coronary revascularization.
While evidence is still pending, there remains room for discussing whether and in whom the aggressive search for myocardial ischemia beyond symptoms may lead to improved cardiovascular outcomes.