Fatty liver index as a predictor for incident type 2 diabetes in community-dwelling adults: longitudinal findings over 12 years

Background: Diagnosing fatty liver and identifying disease status are important for fatty liver related-diseases prevention. The fatty liver index (FLI), which can be easily available in clinical practice, can be very useful for managing fatty liver and preventing related diseases. No large-scale and long-term follow-up prospective studies have investigated the relationship between FLI and incident type 2 diabetes (T2DM) independent of baseline insulin resistance status. Therefore, this study aimed to evaluate the association between FLI and incident T2DM and to determine whether FLI could be used as an indicator of T2DM using a large-sample, community-based Korean cohort over 12 years. Methods: Among the 10,030 total participants, 7,777 (3,676 men and 4,101 women) without diabetes were selected from the Korean Genome and Epidemiology Study (KoGES). FLI grade, which ranged from 0 to 100, was categorized into three groups: low, FLI (< 30); intermediate, FLI (30–59); and high, FLI (≥ 60). The hazard ratios (HRs) with 95% confidence intervals (CIs) for incident T2DM were calculated using multivariate Cox proportional hazards regression models after adjusting for potentially confounding variables. Results: In total, 1,490 individuals (19.2%) developed T2DM during follow-up. Compared to the reference FLI (< 30), the HRs of incident T2DM for the FLI (30–59), and FLI (≥ 60) increased after adjusting for potentially confounding variables, including the HOMA-IR marker. Conclusions: FLI grade at baseline could be a future indicator of T2DM even when prior glucose or insulin (HOMA-IR) levels are normal.