Atherosclerosis is a chronic disease of the arteries characterized by inflammation and plaque building in the arterial wall, eventually leading to stenosis of the vessel. Carotid atherosclerosis (CAS), which is associated with increased cardiovascular risk . Therefore, methods for the early detection and prevention of CAS would be of clinical and societal value.
The present study provides strong evidence that an increasing TyG index is Independently associated with an increased risk of CAS in patients with T2DM. TyG index allow an early detection of carotid atherosclerotic burden and at the same time enhance our ability to determine those individuals who are at greater risk for CAS.
As mentioned above, the HIEC is considered the current gold standard to determine insulin resistance ; however, as an alternative strategy, TyG index has become an attractive option due to the highly available and inexpensive biochemical markers needed for its calculation [23, 24]. Generally, TyG index is dysregulated if insulin resistance occurs. Thus, TyG index has been described as a biochemical marker of insulin resistance.
Insulin resistance is one of the first metabolic abnormalities leading to the development of T2DM, and it is known to be a key mediator of its pathogenesis [25–27]. Insulin resistance is associated with CAS development in patients with T2DM, but the mechanism of action has not been elucidated fully. Insulin is a vascular hormone, it is not only a hormone regulating the glucose level in blood, it is also a signaling molecule in many tissues and cells [28, 29]. The alterations in vascular homeostasis due to endothelial and smooth muscle cell dysfunction are the main features of diabetic vasculopathy favouring a pro-inflammatory/thrombotic state which ultimately leads to atherothrombosis . Hyperglycemia, insulin resistance, and inflammation and metabolic derangements associated with concomitant obesity cause endothelial vasodilator and fibrinolytic dysfunction . A large cohort study found that insulin resistance measured by short insulin tolerance test is Independently associated with CAS in patients with T2DM . The research also proved that individuals with metabolic syndrome are at an increased risk for CAS compared to those without metabolic syndrome . These studies suggested that TyG index is of great value for predicting CAS. Careful consideration of the insulin resistance mechanism would help clarify the exact mechanism by which TyG index of T2DM patients contributes to atherosclerosis.
The correlation of TyG index with diabetic macrovascular disease is unclear, and a study is needed to investigate the predictive value of TyG index for CAS in patients with T2DM. Our cross-sectional study enrolled a relatively large sample with T2DM. We found that an increased TyG index was associated with a high risk of CAS. This is the first study to discover the association of TyG index with CAS in patients with T2DM. Furthermore, as a proxy for insulin resistance, TyG index has the advantage of being clinically applicable because TG and glucose concentrations are measured routinely in patients with T2DM, some patients with T2DM in developing countries refuse carotid ultrasound examination due to economic reasons.
Our Subgroup analysis also showed that when the patient is female, or younger than 65, or suffering from hypertension and obesity, the risk of CAS in patients with T2DM was significantly increased when TyG index increased. Insulin resistance may play a key role. Previous studies have found that female with T2DM are more likely to have dyslipidemia , abdominal obesity  and hypertension , and their vascular endothelial function damage and thrombosis risk are higher than men , and the risk of macrovascular disease is also higher. Studies have pointed out that the rate of progression of Chinese carotid atherosclerosis with age is more extreme. But in this article, with the increase of TyG index, patients with T2DM younger than 65 years of age are at higher risk of developing CAS. The reason may be related to insufficient sample size. Obesity is associated with an increased risk of insulin resistance and T2DM . Obesity are also the main risk factors for the development of CAS and cardiovascular disease . Insulin resistance is associated with a variety of cardiovascular disease risk factors including central obesity, essential hypertriglyceridemia, and low HDL-C , this is consistent with our research results. Prevalence of obesity and the metabolic syndrome is rapidly increasing in developing countries, leading to increased morbidity and mortality due to T2DM and cardiovascular disease . International health agencies and related governments should focus on TyG index of obese patients with T2DM in developing countries. Therefore, it is recommended that patients with T2DM should actively control their weight, blood pressure and blood sugar to reduce the risk of macrovascular events.