In this prospective study, we aimed to identify the relationships between LDL-C/HDL-C ratio, TG/HDL-C ratio with Type 2 Diabetes Mellitus (T2DM), coronary heart disease (CHD) and stroke in Chinese elder adults. Our results indicated a significant association between LDL-C/HDL-C ratio with CHD. However, the association may be interacted by gender, WHR, smoking, drinking and physical activity. Inversely, the association between TG/HDL-C ratio and T2DM was independent on confounders. In addition, the hazard ratios of T2DM, CHD and Stroke were increased with LDL-C, TG/HDL-C ratios.
Dyslipidemia can cause a series of metabolic disorders, which are closely related to abnormal insulin levels, metabolic syndrome and cardiovascular disease.[29, 30] Laboratory investigation found that lipids abnormality was one of the causes of glucose metabolism disorders. Additionally, as a hydrolysate of triglyceride (TG), the free fatty acid is easily reactivated into TG by activation of a non-oxidative metabolic pathway, and then the apoptotic pathway is activated to cause cell death and to decrease the function of islet cells.[14, 32] Besides, the accumulation of free fatty acids in the plasma will enter the cells to hinder the oxidation and utilization of glucose, promote structural changes in the insulin receptor substrate in the liver and muscle, and inhibit insulin signaling, thereby causing insulin resistance.[32, 33] Increased dyslipidemia and glucose metabolism, metabolic syndrome, and elevated risk of an atherosclerotic cardiovascular disease characterized by elevated LDL cholesterol, elevated triglycerides and decreased high-density lipoprotein cholesterol.[14, 15] For a long time, the metabolism of blood lipids has been judged by the traditional indicators LDL-C, TG, HDL-C, and recently found that the ratio of LDL-C/HDL-C had the same effects on the predictability cardiovascular disease.[16, 34, 35]
The lipid ratio is a simple and effective index to identify apparently healthy individuals who are at increased diabetes and cardiometabolic risk. The reaction to blood lipids triggers a more serious disorder of lipid metabolism. Therefore, abnormal blood lipids accelerate evolution and gradually develop into cardiovascular diseases or diabetes. Most people will take measures after they are overweight or after the disease occurs, but people with normal body weight or without T2DM and CVD may also have dyslipidemia and develop lesions. Therefore, we want to use the blood lipid index to screen out high-risk groups early, control the occurrence of cardiovascular diseases and diabetes, and reduce the harm. The result of MY Hong et al revealed the LDL-C/HDL-C ratio and TG were independently associated with diabetes. After the interaction variable was included, the LDL-C/HDL-C ratio remained an independently associated with diabetes, but TG was replaced by TG*LDL-C/HDL-C. However, the significant association was obtained in LDL-C/HDL-C with CHD, the association with T2DM was eliminated in upper LDL-C/HDL-C ratio when included covariates. The result alerted that the association of LDL-C/HDL-C with T2DM may be feint. LDL-C/HDL-C ratio is an independent risk factor for coronary heart disease and it is positively correlated with the severity of coronary artery lesions. In addition, TG/HDL-C ratio was associated with T2DM, and the relationship with stroke also was observed in upper. Increases in plasma triglyceride and decreases in HDL-C have been identified, as risk factors for CHD. Several studies have shown that levels of the triglyceride/HDL-C ratio are closely associated with parameters of cardiovascular risk, and that it can predict the development of CHD and cardiovascular mortality.[40, 41] Meanwhile, high TG/HDL-C ratio in adolescence was associated with hypertension in early adulthood. Contradictorily, the association of high TG/HDL-C ratio with CHD wasn’t observed in our result that informed us this association with CVD may be caused by diabetes.
From the results of the demographic characteristics, the mean age, systolic blood pressure, diastolic blood pressure, BMI, and waist circumference increased with the TG/HDL-C and LDL-C/HDL-C levels. However, with the increasing of LDL-C/HDL-C levels, the proportion of males is increasing gradually, the proportion of females is decreasing, and the proportion of smokers and light manual workers is increasing, while proportion of the drinkers, moderate and heavy physical activists is decreasing. This suggests that males have more dyslipidemia than females and dyslipidemia is more common in smokers in Chinese elder adults, which is consistent with previous study. However, workers with moderate physical activities have lower dyslipidemia than mild manual workers, the reason may be that the fat accumulates hardly and the decomposition products are less in workers with moderate physical activities than obesity. The blood lipids of drinkers are more normal than those who do not drink, which is contrary to the conclusion that alcohol may be a risk factor for dyslipidemia. In order to unify the data collected by on-site questionnaires in different regions, the alcohol-related data only retains the “yes/no drinking”, and the difference in the amount of alcohol consumed by drinkers may trigger the bias in results, which can be further explored.
The present study, was performed with qualified Chinese elder adults and the sample size is large enough for stratification. However, several limitations warrant mentioning. Firstly, we were unable to avoid the potential effects of medication and the presence of other diseases on the concentration of lipid proteins due to inadequate information. Additionally, this is a single-center study and the subjects were periodic health check-ups population could lead to selection bias. Most subjects of the study were recruited from similar regions, where people had similar lifestyles, and the study population was Chinese and findings did not be replicated in other racial groups. Nevertheless, it was helpless that we assessed the prospective risk of cardio-metabolic disease and related organ damage according to those lipoprotein ratios that are needed to fully elucidate the reported relationships.