Individuation of a cut-off value of triglyceride-glucose index for incident diabetes mellitus in patients with essential hypertension

The prevalence of obesity and diabetes, risk factors for atherosclerotic vascular diseases, is increasing worldwide; therefore, it is desirable to early identify them to reduce cardiovascular events. Thus, we investigated whether the triglyceride-glucose index (TyG index), a new marker of insulin resistance, is associated with incident diabetes in patients with newly diagnosed arterial hypertension. We selected 585 patients with newly diagnosed arterial hypertension referred to our tertiary Clinic of Catanzaro University Hospital for the evaluation of their cardiometabolic risk profile. None of the patients had diabetes mellitus at enrollment and took any drug known to affect glucose metabolism. Patients underwent medical history collection, clinical examination and laboratory tests. The TyG index was calculated as the ln [fasting TG (mg/dl) × FPG (mg/dl)/2], as previously suggested. During the follow-up [mean 8.5 years (range 3.1-10.7)], there were 78 new cases of incident diabetes (1.57% patient-year). Patients who developed diabetes mellitus were older and had a higher body mass index (BMI), baseline blood pressure, fasting glucose, insulin, homeostatis model sssessment (HOMA) index, triglyceride, creatinine and hs-CRP mean values, while estimated glomerular filtration rate values were lower. At the Cox regression analysis, covariates significantly associated with incident diabetes were: BMI (HR = 2.842, 95%CI = 2.299-3.514), TyG index (HR = 2.392, 95%CI = 1.745-3.192), age (HR = 1.944, 95%CI = 1.527-2.474), hs-CRP (HR = 1.409, 95%CI = 1.153-1.722), and HOMA (HR = 1.325, 95%CI = 1,079-1.756). The best estimated cut-off value of TyG index in predicting diabetes was 4.71. In addition, we documented a significant relationship between TyG index and HOMA (r = 0.575; p