Evaluation of the Relationship Between Macrovascular Complications and Hemoglobin Glycation Index (HGI) in Patients with Type 2 Diabetes Mellitus

The Hemoglobin Glycation Index (HGI) reflects individual differences in hemoglobin glycation beyond mean blood glucose levels and may provide a more accurate assessment of vascular risk in type 2 diabetes mellitus (T2DM). This retrospective cross-sectional study included 391 adults with T2DM who were treated in the internal medicine outpatient clinic of a tertiary hospital between January and December 2024. Patients were categorized based on the presence of macrovascular complications, including coronary artery disease, ischemic stroke, and peripheral artery disease. HGI was calculated as the difference between measured HbA1c and the HbA1c predicted from fasting plasma glucose using the equation Predicted HbA1c = 0.024 × FPG + 3.1. Patients with macrovascular complications had significantly higher HGI values compared to those without (median (IQR): 1.68 (1.31–2.06) vs. 0.48 (0.11–1.14); p < 0.001). Receiver operating characteristic (ROC) curve analysis demonstrated a strong discriminative power of HGI for identifying macrovascular complications (AUC = 0.870, 95% CI: 0.833–0.908; p < 0.001), with an optimal cutoff value of 1.13 providing 87.6% sensitivity and 74.2% specificity. In multivariate logistic regression analysis, HGI (OR = 6.75, 95% CI: 4.25–10.71; p < 0.001), diabetes duration, and urinary albumin-to-creatinine ratio were independent predictors of macrovascular complications, regardless of HbA1c levels and traditional cardiovascular risk factors. These findings suggest that elevated HGI is closely associated with macrovascular complications and may serve as a simple and reliable marker of glycation-related vascular stress, complementing HbA1c in cardiovascular risk assessment for patients with T2DM.