When should ultrasonography be used to detect asymptomatic carotid atheroma in diabetic patients?

While guidelines for detection of silent myocardial and lower limb ischemia are established, data on screening asymptomatic carotid lesions remain scarce. However, such screening would be costly. Since the prevalence of diabetes increases constantly, it is necessary to keep screening costs low by setting up criteria for the selection of patients at risk of ischemic cerebral attack and those who will need medical or surgical attention. Diabetic patients, particularly type 2, often have many reasons to take anti-platelet agents and lipid-lowering therapy. Therefore, carotid ultrasonography screening would have little effect on treatment modification or on glycaemia and blood pressure objectives, but could improve the prognosis of operable lesions.

A one-time screening program was considered worthwhile if the prevalence of severe asymptomatic stenosis was over 20%. The presence of another arterial occlusive disease or other cardio-vascular risk factors could be a major argument for screening.

Carotid intima-media thickness (IMT) was recognized as a reliable prognostic indicator of heart attack and stroke. It worsens with duration of diabetes, renal failure, cardiac neuropathy and poor long term glycaemic control.

Our review suggests that a one-time carotid ultrasonography screening could be recommended for diabetic patients with coronary disease or lower limb atherosclerosis (secondary prevention), all diabetic patients above 60 years of age, smokers, hypertensive and with hypercholesterolemia; type 1 diabetic patients with poor long term glycaemic control; all type 2 diabetic patients with renal failure, a long duration of ill-controlled diabetes or with a carotid bruit. This literature review should be analyzed with caution. It would be helpful to organize a prospective long term study on all types of diabetic patients, including a carotid ultrasonography screening program by experienced radiologists.