Triglyceride-glucose index (TyG) as a predictor of insulin resistance and peripheral artery disease in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a chronic metabolic illness distinguished by insulin resistance (IR), impaired production of insulin, and elevated blood sugar concentration. Prevention focuses on healthy living & managing risks. Peripheral artery disease (PAD) shares risk factors with type 2 diabetes, but diabetes significantly contributes to its development & progression. Chronic high blood sugar and IR worsen microvascular & macrovascular complications, potentially leading to limb amputation. We aimed in this research to assess the serum triglyceride glucose index (TyG index) level as possible screening & severity biomarker of IR & in prediction of PAD. We further tried to correlate the level of this biomarker with different clinical features of the cases & other laboratory tests. This case-control study was conducted on 110 subjects, classified into two groups: 55 T2DM with no known PAD manifestations and 55 apparently healthy subjects as a control group recruited from the internal medicine, diabetes, and endocrinology outpatient clinics at Kasr Al Ainy Hospital, Cairo University, across a 20-month duration from October 2022 to March 2024. Data collection included the lipid profile, fasting insulin, fasting blood glucose (FBS), & glycated hemoglobin (HbA1c). Homeostatic model assessment of insulin resistance (HOMA IR) has been determined with regard to formula: HOMA-IR = {fasting glucose (milligram per decilitre) ×fasting insulin (international unit per millilitres)} /405. The TyG index has been determined as: ln (fasting triglycerides [milligram per decilitre] × fasting blood glucose [milligram per decilitre] /2). The ankle-brachial index (ABI) has been calculated utilizing a high-resolution color-coded Doppler Ultrasonography and the presence of PAD was described as right or left ABI ≤ 0.9. Statistical analyses focused on exploring the efficacy of TyG index for diagnosis of IR and PAD. PAD is significantly greater among diabetic cases in comparison with control group (p value < 0.001). In diabetic cases, a significant positive association has been detected between triglyceride glucose index (TyG index) & (duration of diabetes, total cholesterol, Hb A1c, fasting insulin, and HOMA IR) with a significant negative association has been found among TyG index & ABI with p value < 0.001. ROC curve was done for TyG index for diagnosis of IR showed that a cut off value above nine had a sensitivity & specificity 98% and 93% respectively with area under the curve (AUC) 0.98 with p value < 0.001. ROC curve was done for TyG index + for diagnosis of PAD showed that a cut off value > 9.7 showed a higher sensitivity & specificity 89%and 90% respectively with AUC 0.9 with p value < 0.001. The logistic regression model showed that TyG index is the only indicator of PAD. We report a significant correlation among TyG index & both of IR & PAD. TyG index is an inexpensive, rapid marker that may be applied in the determination of IR& the prediction of PAD in type 2 diabetic cases.