Visceral adipose tissue mediates the relationship between left ventricular global longitudinal strain and insulin resistance among adults living with type 2 diabetes

BACKGROUND: Adipose tissue distribution plays a crucial role in the development of cardiovascular complications. In particular, visceral adipose tissue (VAT) has been linked to insulin resistance (IR) and cardiovascular disease (CVD). However, the relationship between VAT, cardiac dysfunction and the meditation capacity of VAT related to IR has not been fully characterized. METHODS: This cross-sectional study included adults living with type 2 diabetes (T2D). VAT was measured using electrical bioimpedance and also estimated with the Metabolic Score for Visceral Fat (METS-VF). LV function was assessed using left ventricular global longitudinal strain (LV-GLS) by speckle tracking echocardiography analysis. Spearman correlation coefficients, adjusted linear regression models guided by direct acyclic diagrams and causal mediation analysis were performed. RESULTS: Among 195 adults living with T2D (median age: 57, IQR: 49-64, women: 63%), VAT showed a positive association with LV-GLS (β = 0.482, 95% CI: 0.060-0.904, p = 0.039) after adjusting for relevant confounders. The effect was strongly replicated using METS-VF as a surrogate for VAT. The mediation analysis revealed that VAT accounted for 60.9% (95% CI: 15.82-171) of the total effect between IR and LV-GLS. CONCLUSION: This study demonstrated a positive association between VAT and LV-GLS. This relationship was consistently observed using the clinical surrogate METS-VF. Visceral adiposity was identified as a strong mediator in the relationship between IR and LV-GLS, underscoring its role in the pathophysiology of cardiovascular disease in patients with T2D.