Utilization of Triglyceride Levels and Estimated Average Plasma Glucose Using Glycated Hemoglobin in Assessing Insulin Resistance: TyHBA1c index

IntroductionInsulin resistance (IR) is a metabolic disorder characterized by reduced sensitivity to the physiological effects of insulin, leading to an impaired ability of cells to take up glucose from the bloodstream. There are multiple indices available for assessing IR, however, they often rely on a single glycemic parameter at a specific moment, leaving a gap in the evaluation of IR over a certain period. ObjectiveTo develop a novel index for assessing IR by combining triglyceride levels and estimated glycemia through glycated hemoglobin (HBA1c). MethodWe used the fasting triglycerides and glucose levels (TyG) index formula by replacing fasting glucose with estimated average glucose calculated through HbA1c. The study included 200 laboratory samples, including fasting glucose, triglycerides, insulin, homeostasis model assessment for IR (HOMA-IR) index, TyG index, and estimated average glucose by HbA1c. The ideal cut-off value of the TyHBA1c index for estimating IR was established compared to the HOMA-IR index, and TyG index using a receiver operating characteristic (ROC) analysis. A weighted kappa test was used to estimate the diagnostic agreement between the TyHBA1c index and the HOMA-IR and Tyg index. ResultsThe TyHBA1c index showed a higher correlation with the HOMA-IR index (r = 0.273, p = 0.000) compared to the TyG index (r = -0.617, p < 0.000). An association between HBA1c and the HOMA-IR index was observed (r = 0.215, p = 0.002). The ROC curve showed that the cutoff value for the TyHBA1c index to best estimate IR is Ln 4.74 (sensitivity 85.0% and specificity 95.0%) compared to the TyG index. The weighted kappa test revealed moderate agreement between the TyHBA1c index and the HOMA-IR index (k = 0.45, p = 0.006), and satisfactory agreement between the TyHBA1c index and the TyG index (k = 0.71, p = 0.009). ConclusionOur results demonstrated a strong association between the TyHBA1c index and TyG index, and the HOMA-IR index, suggesting that the TyHBA1c index may be more a indicator of IR, and more a tool in clinical practice for assessing IR.