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Carotid ultrasound investigation as a prognostic tool for patients with diabetes mellitus

Author: Valerie Ulai

Diabetes mellitus is more commonly known simply as diabetes. It’s when the pancreas does not produce enough insulin to control the amount of glucose, or sugar in the body [1]. Diabetes mellitus is associated with increased morbidity and mortality, and is linked to some acute but mainly chronic complications, based on functional and structural damages to the blood vessels [2].

The disease is, unsurprisingly, a major risk factor for cardiovascular disease and a plethora of experimental and clinical studies link hyperglycemia (high blood sugar) to the development and progression of atherosclerosis (buildup of fats, cholesterol and other substances in and on the artery walls that can restrict blood flow), especially in the carotid artery [2]. As confirmed with a study done by Bosevski in 2014, hyperglycemia, duration of diabetes and arterial hypertension are independent factors for carotid atherosclerosis in diabetes, and aging as its predictor in this population [3].Also proven by Angelis at el in their study, diabetics were three times more likely to develop carotid stenosis than the non-diabetics with an odds ratio of 3.152, (95% CI, 2.032-4.889) [4]. Various mechanisms by which diabetes contributes to cardiovascular disease and atherosclerosis have been identified. Alterations of the vessel wall, due to endothelial and smooth muscle cell dysfunction, are the main characteristics of diabetic vasculopathy [2].

At present, carotid ultrasound is recommended in diabetic patients with cerebrovascular symptoms [3]. Since the prevalence of diabetes increases constantly, it has been recommended that diabetic patients with atleast one more risk factors and for diabetic patients above 60 years of age can undergo this investigation [3].

One of the main evidence of the connection between carotid artery disease and diabetics is measuring their carotid intima-media thickness (two layers of the carotid artery-the intima and media) using ultrasound. This has been defined as a useful tool for risk stratification of this population, because performance of carotid ultrasound is simple, cost-effective and does not pose any risk to the patient [5]. In addition, ultrasound assessment of carotid arterial atherosclerotic disease has become the first choice for carotid artery stenosis screening, permitting both the evaluation of the macroscopic appearance of plaques, as well as flow characteristics in the carotid artery [6]. The scanning mostly focuses on internal carotid artery (ICA) stenosis, with the use of both criteria: the one published by Society of Radiologists in Ultrasound (SRU) and the Sonographic NASCET Index.

1. Developed recommendations for the diagnosis and stratification of ICA stenosis by SRU includes [6];

[PSV = peak systolic velocity; EDV = end-diastolic velocity; ICA = internal carotid artery; CCA = common carotid artery]

  • normal

  • ICA PSV is <125 cm/sec and no plaque or intimal thickening is visible sonographically

  • additional criteria include ICA/CCA PSV ratio <2.0 and ICA EDV <40 cm/sec

  • <50% ICA stenosis

  • ICA PSV is <125 cm/sec and plaque or intimal thickening is visible sonographically

  • additional criteria include ICA/CCA PSV ratio <2.0 and ICA EDV <40 cm/sec

  • 50-69% ICA stenosis

  • ICA PSV is 125-230 cm/sec and plaque is visible sonographically

  • additional criteria include ICA/CCA PSV ratio of 2.0-4.0 and ICA EDV of 40-100 cm/sec

  • ≥70% ICA stenosis but less than near occlusion

  • ICA PSV is >230 cm/sec and visible plaque and luminal narrowing are seen at gray-scale and color Doppler ultrasound (the higher the Doppler parameters lie above the threshold of 230 cm/sec, the greater the likelihood of severe disease)

  • additional criteria include ICA/CCA PSV ratio >4 and ICA EDV >100 cm/sec

  • near occlusion of the ICA

  • velocity parameters may not apply, since velocities may be high, low, or undetectable

  • diagnosis is established primarily by demonstrating a markedly narrowed lumen at color or power Doppler ultrasound

  • total occlusion of the ICA:

  • no detectable patent lumen at gray-scale ultrasound and no flow with spectral, power, and color Doppler ultrasound

  • there may be compensatory increased velocity in the contralateral carotid

2. Sonographic NASCET Index: proposed the incorporation of distal ICA flow velocity information on the conventional carotid doppler study improving the diagnostic accuracy of PSV, which includes [6];

  • <15% stenosis

  • deceleration spectral broadening with a peak systolic velocity (PSV) <125 cm/s

  • 16-49% stenosis

  • pansystolic spectral broadening with a PSV <125 cm/s

  • 50-69% stenosis

  • pansystolic spectral broadening with a PSV of >125 cm/s and

  • end diastolic velocity (EDV) <110 cm/s or ICA/CCA PSV ratio >2 but <4

  • 70-79% stenosis

  • pansystolic spectral broadening with PSV >270 cm/s

  • or

  • EDV >110 cm/s or

  • ICA/CCA PSV ratio >4

  • 80-99% stenosis: EDV >140 cm/s

  • complete occlusion: no flow; terminal thump

These two criteria was also used by Hoke et al in their study which identifies that patient with diabetes and asymptomatic carotid stenosis are at an exceptional high risk for adverse outcome [2]. If a patient at time of inclusion was diagnosed with both diabetes mellitus and carotid stenosis above 50%, the patient had only approximately 20% chance to survive the following 12 years. These findings are more than alarming. They further identified that combining carotid stenosis with diabetes mellitus improved the risk stratification by near 40% for the risk of all-cause and cardiovascular death, respectively [2]. In contrast, the clinical diagnosis diabetes mellitus, based on Hemoglobin A1C test (hba1c) and serum glucose levels alone, displayed a highly significant, but rather weak association with (cardiovascular) mortality in patients in asymptomatic carotid atherosclerosis after 12-years of follow-up [2].

Therefore, it is proven that diabetic patients can have carotid stenosis and with this, they are at exceptional high risk for all-cause and cardiovascular death. Thus, routine ultrasound investigation of the carotid arteries is a valuable prognostic tool for patients with diabetes mellitus, even with no cardiovascular symptoms.


1. WebMD. Diabetes Insipidus vs. Mellitus Differences: Symptoms, Treatment and More. Available on

2. Carotid ultrasound investigation as a prognostic tool for patients with diabetes mellitus | Cardiovascular Diabetology | Full Text. Available on

3. PUbMed. Carotid artery disease in diabetic patients. Available on

4. PubMed. Prevalence of carotid stenosis in type 2 diabetic patients asymptomatic for cerebrovascular disease. Available on

5. [Google scholar]. American Diabetes A. 10. Cardiovascular disease and risk management: standards of medical care in diabetes-2019. Diabetes Care. 2019;42 (Suppl 1):S103–23.

6. Ultrasound assessment of carotid arterial atherosclerotic disease | Radiology Reference Article | Available on

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