Coronary artery calcium scanning in asymptomatic patients with diabetes mellitus: a paradigm shift.

Coronary artery calcium (CAC) is the most powerful cardiac risk prognosticator in the asymptomatic population, with consistent superiority to all risk factor-based paradigms. More recently, the strong prognostic value of changes in CAC has been demonstrated. The application of CAC to asymptomatic patients with diabetes mellitus (DM), all of whom have been presumed to be of high risk, has yielded a range of risks from low to high, proportional to the amount of calcified plaque, as in patients without DM. These risks are higher than in non-diabetic patients at corresponding CAC levels, except for those without CAC who have the same low risk as non-diabetic patients. In addition, the value of serial scanning to assess plaque progression and prognosis in people with DM has been demonstrated. Therefore, we propose that: (i) DM is not a coronary artery disease equivalent; (ii) CAC can be used routinely in all asymptomatic diabetic patients >40 years of age, as proposed by American College of Cardiology/American heart Association guidelines; and (iii) serial CAC scanning be considered for evaluation of the response to therapy.