Type 2 DM is not coronary artery disease equivalent.

Sir,

This letter comes in response to the article published in Jan-Feb 2012 issue by Sandeep Chopra and Soumia Peter titled “Screening for Coronary Artery Disease in Patients with Type 2 DM: An evidence based review”.

Coronary Artery Disease (CAD) is the foremost complication of Type 2 DM. Major support to the concept that Type 2 DM is a CAD equivalent came from Haffner et al's study.[1] However this study had major pitfalls it study was not powered to look into CAD. Majority of the patients were hypertensive, most patients with diabetes had uncontrolled glycemia, and their lipids were not at target as per current standards. Subsequently one more study showed in fact patients with T2DM were at lower risk for cardiovascular outcomes compared to patients with established CAD.[2] Major clarification regarding this came from the Barbara et al.'s[3] study wherein they studied the influence of single and multiple risk factors on the 10-year cumulative incidence of fatal and nonfatal CAD and cardiovascular disease (CVD) in diabetics and non-diabetics. This study showed that CAD risk equivalence in diabetics depends on concomitant risk factors for CAD than on diabetic status alone.[3] A recent meta-analysis involving in excess of 45,000 patients did not support the hypothesis that diabetes is CAD equivalent.[4] Even DIAD study showed that cardiac event rates in diabetic subjects were low.[5] In fact it is the coronary artery status that determines the future cardiac event rate than the diabetic state per se. In epidemiological studies, diabetes was shown as CAD risk equivalent mainly because moderate-risk diabetic patients without significant CAD and very high-risk diabetic patients with significant CAD add up to a grand total of high-risk diabetic patients.[6] Even ADA recent guidelines do not recommend routine screening for CAD in asymptomatic diabetic patients, as it does not improve the outcomes as long as CVD risk factors are treated, and has level A of evidence.[7] Hence, it is not the diabetic status but the additional CAD risk factors which confer the CAD equivalent state in diabetic subjects. I feel CAD risk prevention strategy in diabetes subjects still should be based on the absolute risk rather than diabetic state alone.