With the increasing complexity of the modern life style, the work pressure inyoung people is increasing. The trend of diabetes mellitus in youth is gradually emerging due to the disruption of sleep and circadian rhythms [22]. Especially in youth, the fluctuating hyperglycemia can increase the risk of carotid atherosclerosis and other complications compared to persistent hyperglycemia [23, 24]. The incidence of diabetes combined with carotid atherosclerosis is growing fast. Chronic inflammation plays a decisive role in the development of diabetic vasculopathy [25]. An earlier study had shown that diabetes itself is an inflammatory disease [2], and the occurrence and development of carotid atherosclerosis are also closely related to the vascular inflammatory reactions.
The increased incidence of type 2 diabetes mellitus in youth is closely related to the gene factors and environmental factors, such as the family history of diabetes, unhealthy diet, overweight, excessive fat intake, low frequency of physical activity, long sit-in time, alcohol intake, etc. [26]. Some studies have pointed out that hyperlipidemia in pre-diabetic patients is an important risk factor after the thickening of carotid artery intima-media [27]. Among young people, IMT thickening is associated with systolic blood pressure [28], while smoking also exacerbates atherosclerosis. Therefore, the overall risk of stroke and ischemic stroke hassignificantly increased [29]. A study found that the majority of young type 2 diabetes mellitus patients were obese [30], and the increased IMT in young adults was associated with obesity [31]. Type 2 diabetes mellitus in youth becomes quickly aggressive after onset, as the rate of functional impairment in the islet B cells is swift. Therefore, the risk of comorbidities and death is higher [32]. The reported foreign studies indicated that the incidence of carotid plaque in type 2 diabetes mellitus is 64.3% [33]. The result of this study showed that the risk factors for carotid atherosclerosis in young patients with newly diagnosed type 2 diabetes were mainly hypertension, hyperlipidemia, smoking, and obesity. These outcomes were consistent with the results of previous studies.
Some studies have shown that the basic pathophysiological changes in carotid atherosclerosis plaque (CAP) caused by diabetes are arterial vascular injury and following an inflammatoryresponse [34]. Diabetes mellitus is recognized as an important harmful factor in the formation of CAP [35]. Therefore, the detection of the body’s inflammatory response is of considerable significance to judge the development and prognosis of atherosclerosis [36, 37].
PLR is considered to be a new biomarker that reflects the degree of systemic inflammation [38–41]. A high platelet count and low lymphocyte count or high PLR value may contribute to the progression of atherosclerosis and could be associated with adverse events of ischemic prognosis of cardiovascular and cerebrovascular diseases, which reflects the high risk of plaque shedding [10, 42, 43]. NLR is a risk factor for atherosclerotic plaque formation and arterial stenosis [44, 45]. Studies have reported that NLR is associated with blood glucose regulation, insulin resistance (IR), diabetes with acute myocardial infarction, diabetic retinopathy (DR), and diabetic nephropathy (DN) [46, 47].
The results of this study showed that the PLR value and NLR value of newly diagnosed type 2 diabetes young patients were significantly higher than those in normal youth. A series of inflammatory responses caused by hyperglycemia leads to abnormalities of vascular endothelium and blood vessels, thereby mediating the abnormal functional metabolism of the smooth muscle cells [2, 35]. The inflammatory factors will then result in significantly elevating of PLR and NLR values.Abnormal immune function can easily lead to the formation of vascular plaque, while unstable plaque can lead to cerebral infarction [47]. Logistic regressionshowed that PLR and NLR values were significantlyrelated to the onset of arterial plaque in newly diagnosed type 2 diabetes patients. The possible mechanisms are as follows. When oxidative stress and inflammation occur, the release of corticosteroids and catecholamines in the plasma increases and leads to bone marrow suppression.The lymphocyte apoptosis can be observed during plaque formation, rupture, and thrombosis [48]. Under the action of atherosclerosis risk factors, granular proteins released by neutrophils cause endothelial dysfunction. The released proteases can also aggravate endothelial erosion and induce the monocyte accumulation to the atherosclerotic lesions. This event can stimulate macrophage maturation and foam cell formation, and promote the atherosclerotic plaque formation [49].The rapid increase in the number of platelets can change the blood flow rate, promote the synthesis of C-reactive protein and fibrinogen. It can also facilitate the endothelial cells and lymphocytes to produce more inflammatory substances, which in turn can enhance the inflammatory response and the progress of atheromatous plaques [50]. This shows that the PLR and NLR values can be used as novel inflammation indicators to assess the severity of plaque. They can clinically assist the early and rapid screening of patients with high-risk carotid atherosclerosis to make timely and effective treatment strategies.
In this study, ultrasound Doppler was used to evaluate the thickness of IMT. The results showed that the PLR and NLR values of patients in grade III plaque group were higher than those in grade II plaque groupand in the grade I plaque group. The level of PLR and NLR in the patients of the plaque group II was higher than that in the grade I plaque group.With the increase of plaque grade, PLR and NLR values of patients also increased due to the aggravation of chronic inflammation. Along with the increased release of inflammatory mediators, the platelets were activated. Various enzymes, receptors, and cytokines prompt further platelet activation [5], which would cause platelets in the blood to rise quickly [51].On the contrary, some studieshave shown that lymphocytes are usually reduced during the pathogenesis of inflammatory reactions, which is a relatively common manifestation of the body’s stress response, normally accompanied by increased corticosteroids [44], which may be related to the role of lymphocytes in protecting plaque stability [52]. Through direct contact and the secretion of soluble mediators, platelets and lymphocytes interact and form intercellular aggregates. At the same time, platelets can also promote the recruitment of lymphocytes in the injured blood vessel wall [6]. An increase in platelet count reflects a potential inflammatory response. Some inflammatory mediators stimulate megakaryocyte proliferation to cause the associatedincrease in platelets. In addition, high platelet count indicates a high tendency to form platelet-rich thrombocytes on atherosclerotic plaques. However, lymphocytes represent the inactive state of the inflammation control process [53]. The decrease in the total number and a relative number of circulating lymphocytes during an ischemic event may be related to that the physiological stress that leads to the increase in cortisol and catecholamine levels, causing the lymphocyte redistribution [54].
The results of this study suggest that the PLR value and NLR value are related to the plaque grade, indicating that the change in these values may reflect the severity of carotid plaque. In clinical work, the PLR and NLR values can be used as effective indicators to measure the severity of carotid artery and inflammatory response. It provides evidence for assessing the condition and guiding treatment modality. At the same time, it is of far-reaching significance to conduct personalized out-of-hospital antiplatelet and anti-arteriosclerotic drugs therapy based on different PLR values and NLR values.
However, this study has certain limitations. Firstly, due to time, funding, personnel, and other constraints, this study did not follow up on the selected young patients with newly diagnosed type 2 diabetes, making it hard to understand the dynamic evolution between the CAP and PLR, NLR values. Therefore, it could not fully evaluate the relationship between PLR and NLR values and carotid atherosclerosis in young people. Secondly, the blood routine test has more variability in different periods, and it is arbitrary to make a judgment based on the result of only one blood draw. It may be necessary to test the results multiple times and calculate the average value, which may increase the reliability of the results. Lastly, the number of cases included in this study is relatively small.