Thigh Muscle Quality Predicts the Incidence of Type 2 Diabetes Mellitus

Background: Ectopic fat infiltration in skeletal muscle, particularly in the thigh, may impair muscle function and contribute to metabolic dysfunction. However, its predictive value for incident type 2 diabetes mellitus remains understudied. Methods: We conducted a prospective cohort study of 2,129 East Asian adults (mean age, 57.4±16.9 years; body mass index, 25.0±3.9 kg/m2; 48.5% male) with one or more cardiometabolic risk factors but no diabetes at baseline. Low-density muscle (LDM) area was quantified using non-contrast computed tomography at the midthigh level, with attenuation values of 0-30 Hounsfield units defined as LDM. The association between LDM area and incident diabetes was assessed over a median followup of 7.4 years. Results: During follow-up, 201 males (19.5%) and 156 females (14.1%) developed diabetes. Those who developed diabetes had higher baseline glycosylated hemoglobin levels (6.1%±0.3% vs. 5.7%±0.4%) and larger LDM areas (48.8±14.2 cm2 vs. 38.1±13.2 cm2, both P<0.05). In adjusted Cox models, a large LDM area was independently associated with incident diabetes (hazard ratio [HR], 2.36; 95% confidence interval [CI], 1.52-3.67 for males and HR, 2.15; 95% CI, 1.28-3.61 for females). Incorporating LDM area into models with traditional risk factors improved predictive accuracy (area under the curve increased from 0.810 to 0.838 in males and from 0.893 to 0.908 in females). Conclusion: LDM area, an indicator of thigh muscle quality and intramuscular fat infiltration, is an independent predictor of incident diabetes.