Detection of Ischemia in Asymptomatic Diabetes (DIAD) Trial

The Detection of Ischemia in Asymptomatic Diabetes (DIAD) trial asked the question of whether screening adenosine-stress myocardial perfusion imaging (MPI) of asymptomatic diabetics would result in improved outcomes. The idea was that since diabetics suffer from silent (asymptomatic) ischemia, early detection of coronary artery disease (CAD) would improve outcomes.

The authors randomized about 1,200 patients between the ages of 50 and 75 who had type 2 diabetes to two groups: Those in the first group would be screened for CAD with SPECT MPI. Those in the second group would be managed clinically without SPECT MPI screening. The patients were followed up for an average of about 5 years.

The following patients were excluded:

• Angina pectoris or chest discomfort
• Stress test or coronary angiography within the prior 3 years
• History of myocardial infarction, heart failure, or coronary revascularization
• Abnormal rest ECG
• Clinical indication for stress testing
• Active bronchospasm (which would prevent the use of adenosine
• Limited life expectancy due to cancer or end-stage renal or liver disease

The DIAD trial concluded that SPECT MPI of patients with asymptomatic diabetes didn’t reduce the rate of cardiac events (cardiac deaths and nonfatal infarctions). The authors admit that the study was underpowered to detect small differences between the groups, since "cardiac event rates were significantly lower than originally anticipated at the time of the design of the study" (out of the 1,200 or so patients, fewer than 20 patients in each group had cardiac events).

Finally, despite the similar outcomes in the two groups, more patients in the screened group ended up getting cardiac catheterizations.

References

Young LH, et al. Cardiac outcomes after screening for asymptomatic coronary artery disease in patients with type 2 diabetes: the DIAD study: a randomized controlled trial. JAMA. 2009 Apr 15;301(15):1547-55.