Letter to the Editor in Response to “A novel index for diagnosis of type 2 diabetes mellitus: Cholesterol, high density lipoprotein, and glucose ( CHG ) index”

To the Editor, We read with great interest the article “A novel index for diagnosis of type 2 diabetes mellitus: cholesterol, high density lipoprotein, and glucose (CHG) index1.” This accessible tool has significant potential for screening in resource-limited settings. However, two methodological considerations merit clarification to strengthen its validity. First, the CHG index was derived and validated within the high-risk MASHAD cohort, which is enriched for cardiovascular and metabolic disorders. This may lead to spectrum bias, potentially overestimating its diagnostic accuracy (AUC 0.864) compared to its performance in a general, lower-risk screening population. Could the authors clarify whether external validation has been or is planned in a more representative community-based cohort to assess its true generalizability? Second, the analysis did not account for lipid-lowering medication use, particularly statins, which are common in diabetic populations. Statins directly alter total cholesterol and may influence HDL-C, both core components of the CHG index2. This introduces a potential confounder, as the index may reflect treatment effects rather than underlying metabolic pathology. Adjusting for or stratifying by statin use would help clarify the index's true diagnostic performance. Addressing these points would enhance the clinical interpretability and generalizability of the CHG index. We commend the authors for their work and look forward to their insights. The authors declare 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. Ying Li, Lei Jin: methodology, writing—review and editing. Data sharing is not applicable to this article as no datasets were generated or analyzed during the current study.