To determine the association among nonalcoholic fatty liver disease (NAFLD), metabolic function, and cardiac function in obese adolescents.

Intrahepatic triglyceride (IHTG) content (magnetic resonance spectroscopy), insulin sensitivity and β-cell function (5-hour oral glucose tolerance test with mathematical modeling), and left ventricular function (speckle tracking echocardiography) were determined in 3 groups of age, sex, and Tanner matched adolescents: (1) lean (n = 14, body mass index [BMI] = 20 ± 2 kg/m²); (2) obese with normal (2.5%) IHTG content (n = 15, BMI = 35 ± 3 kg/m²); and (3) obese with increased (8.7%) IHTG content (n = 15, BMI = 37 ± 6 kg/m²).

The disposition index (β-cell function) and insulin sensitivity index were 45% and 70% lower, respectively, and whole body insulin resistance, calculated by homeostasis model of assessment-insulin resistance (HOMA-IR), was 60% greater, in obese than in lean subjects, and 30% and 50% lower and 150% greater, respectively, in obese subjects with NAFLD than those without NAFLD (P < .05 for all). Left ventricular global longitudinal systolic strain and early diastolic strain rates were significantly decreased in obese than in lean subjects, and in obese subjects with NAFLD than those without NAFLD (P < .05 for all), and were independently associated with HOMA-IR (β = 0.634). IHTG content was the only significant independent determinant of insulin sensitivity index (β = −0.770), disposition index (β = −0.651), and HOMA-IR (β = 0.738).

These findings demonstrate that the presence of NAFLD in otherwise asymptomatic obese adolescents is an early marker of cardiac dysfunction.