Comment on the article titled “Association of the triglyceride‐glucose index with subclinical left ventricular dysfunction in type 2 diabetes mellitus patients: A retrospective cross‐sectional study”

To the Editor, Diabetes mellitus is one of the foremost causes of cardiovascular disease-related morbidity and mortality worldwide. Significant alterations in the anatomy and physiology of the heart occur before the onset of clinical cardiac disease in patients with diabetes. Among these cardiac changes, the early detection and management of subclinical left ventricular dysfunction (SLVD) is vital in preventing cardiovascular disease progression. In the Journal of Diabetes Investigation, Sun et al.1 examined whether the triglyceride-glucose (TyG) index, a surrogate marker of insulin resistance, is related to the risk of SLVD in hospitalized patients with type 2 diabetes. They showed that the TyG index is an independent indicator of SLVD in this population after controlling for various confounding factors1. The detection of a high risk of SLVD linked to insulin resistance using the TyG index, but not with the more widely used homeostasis model assessment 2 for insulin resistance, significantly increased the value of this clinical study. However, we would like to discuss a few variables that might be useful for investigating this relationship. First, clinical factors and biochemical measurements were well presented in the study1, but no information was provided on the history of antidiabetic drugs. These data could make a significant contribution to this study, because antidiabetic drugs can exert a significant protective effect on the cardiovascular system with a mechanism partially independent of the hypoglycemic effect. A meta-analysis of 48 randomized controlled trials and 4,790 participants with diabetes found that sodium–glucose cotransporter type 2 inhibitors and glucagon-like peptide-1 agonists showed a beneficial effect on reducing the risk of heart failure by improving the left ventricular (LV) end-diastolic diameter, LV ejection fraction and LV end-systolic volume2. Furthermore, in the same study, dipeptidyl peptidase-4 inhibitors were found to increase the LV end-diastolic volume and heart failure2. Second, physical activity is beneficial for cardiovascular risk factors, because it enhances endothelial function and antithrombotic activities, and improves insulin resistance and blood pressure. Both aerobic and anaerobic exercises can be preventive and therapeutic for chronic health conditions. Resistance and aerobic exercises can cause improvement in vascular smooth muscle function and stiffness in type 2 diabetes. Meta-analysis of the effects of exercise on metabolic outcomes in type 2 diabetes showed that different exercise programs improved glucose homeostasis and insulin resistance in adults3. In contrast, in an observational study, exercise training protocol was found to improve left and right ventricular systo-diastolic dysfunction using tissue Doppler velocity and strain imaging measurements, suggesting a positive impact of physical activity on subclinical changes in ventricular function4. Thus, taking into account the modulation of exercise-induced insulin resistance and ventricular dysfunction when interpreting the results of the study might increase the clarity of findings. In conclusion, evidence from this study suggests that a higher TyG index is independently associated with an increased risk of SLVD. These results need to be confirmed in larger populations, but the inclusion of antidiabetic drugs and physical activity as variables in statistical models beforehand might help us better understand the relationship between the TyG index and SLVD. The author declares no conflict of interest. Approval of the research protocol: N/A. Informed consent: N/A. Registry and the registration no. of the study/trial: N/A. Animal studies: N/A.