Fatty liver index-defined hepatic steatosis and impaired fasting glucose differentially associate with incident diabetes and cardiovascular events in older adults: a nationwide cohort study

Background Hepatic steatosis and prediabetes are increasingly prevalent among older adults; however, their respective impacts on cardiometabolic outcomes remain unclear. We aimed to evaluate the associations of hepatic steatosis and prediabetes with incident diabetes and cardiovascular outcomes in this population. Methods This nationwide cohort study included 142,518 adults aged ≥ 65 years without diabetes. Hepatic steatosis was defined using the fatty liver index (FLI ≥ 60), and impaired fasting glucose (IFG) was defined by fasting glucose levels of 100–125 mg/dL. Outcomes included incident diabetes and composite major adverse cardiovascular events (MACE), comprising myocardial infarction, stroke, heart failure, or cardiovascular death, which were analyzed using multivariable Cox proportional hazards models and Fine–Gray subdistribution hazard models. Results At baseline, FLI-defined hepatic steatosis was identified in 6.6% of participants, while 30.6% had IFG. After multivariable adjustment, FLI-defined hepatic steatosis was associated with incident diabetes (SHR 1.67; 95% CI 1.59–1.76; P < 0.001) and composite MACE (SHR 1.21; 95% CI 1.15–1.29; P < 0.001). IFG was associated with an increased risk of incident diabetes (SHR 2.54; 95% CI 2.47–2.62; P < 0.001) but was not independently associated with composite MACE. In joint analyses, FLI-defined hepatic steatosis was consistently associated with an elevated risk of composite MACE regardless of glycemic status, with SHRs of 1.23 (95% CI 1.14–1.32; P < 0.001) among normoglycemic individuals and 1.20 (95% CI 1.11–1.31; P < 0.001) among those with IFG. In contrast, IFG without FLI-defined hepatic steatosis was not associated with an increased risk of composite MACE compared with normoglycemic individuals without FLI-defined hepatic steatosis. Conclusion In older adults, FLI-defined hepatic steatosis is a strong predictor of both incident diabetes and cardiovascular events, whereas IFG shows no independent association with cardiovascular outcomes. Trial registration Not applicable (retrospectively registered).