Purpose <p>Traditional markers such as HbA1c and BMI are commonly used to assess metabolic risk in adolescents with type 1 diabetes mellitus (T1DM), but novel biomarkers like the triglyceride-glucose (TyG) index and phase angle (PA) may provide a more comprehensive evaluation of metabolic risk. However, their potential role in this population remains unclear. We aimed (1) to evaluate the association of the TyG index and PA with glycemic control, cardiovascular risk and body composition in adolescents with T1DM, and (2) to determine optimal cut-off points for these biomarkers to predict metabolic risk.</p> Methods <p>Seventy-three adolescents (46.6% female, 10–19 years) with T1DM from two hospitals were included in this cross-sectional study. Sociodemographic, bioelectrical impedance (BIA) and clinical data were collected during routine visits. The TyG index was calculated from fasting triglyceride and glucose levels, and PA was measured via BIA. Correlations were analyzed using Pearson or Spearman coefficients, and ROC curve analyses were used to determine optimal cut-off points.</p> Results <p>PA correlated positively with skeletal muscle and fat-free mass and inversely with cardiovascular risk indicators. TyG was strongly associated with adiposity, glycemic variability and cardiovascular risk markers. A preliminary TyG threshold of 8.09 was identified, while no PA cut-off could be established.</p> Conclusions <p>PA and the TyG index are promising, non-invasive biomarkers that complement traditional measures in assessing metabolic risk in adolescents with T1DM. Integrating these biomarkers into routine evaluation may enhance early risk detection and support holistic management in this population.</p> Trial registration number <p>NCT07021326.</p>