Elevated liver fat content is independently associated with insulin resistance in people with type 1 diabetes

BACKGROUND: Insulin resistance is associated with metabolic dysfunction-associated steatotic liver disease (MASLD) in the general population, but its relationship with MASLD in people with type 1 diabetes (T1D) remains insufficiently defined. METHODS: /min hyperinsulinaemic-euglycaemic clamp (HEC) to quantify whole-body glucose disposal (M-value, mg/kg/min). Insulin sensitivity was further assessed using the 13C glucose breath test (13C-GBT) and the estimated glucose disposal rate (eGDR). Liver fat content (LFC) was measured by magnetic resonance spectroscopy, and vibration-controlled transient elastography was performed. Participants were stratified 1:1 by MASLD status based on mean LFC >/≤5.56%. RESULTS: =0.47). Lower M-value was associated with MASLD (adjusted OR 3.12, 95% CI 1.17-8.37, p=0.024). Both 13C-GBT (aOR 1.54, 95% CI 1.03-2.33, p=0.033) and eGDR (aOR 1.61, 95% CI 1.09-2.38, p=0.016) were also independently associated with MASLD. CONCLUSION: Insulin resistance is independently associated with MASLD in adults with T1D. IMPACT AND IMPLICATIONS: This study addresses the limited understanding of how MASLD relates to insulin resistance in T1D. We show a robust association between LFC and insulin resistance using gold standard and practical non-invasive measures. These findings may help clinicians identify metabolically at-risk individuals with T1D, although further research is required to clarify whether screening and targeted intervention improve outcomes.