HbA1c of 5.8% or higher as the most useful indicator for recommendation of ultrasonography to detect nonalcoholic fatty liver disease.

Background and Aim: Nonalcoholic fatty liver disease (NAFLD) is closely associated with metabolic syndrome. This study was performed to examine the association between NAFLD and each factor of metabolic syndrome and to identify the factors that are most strongly associated with NAFLD in participants undergoing health checkups. Methods: We studied 6538 participants who underwent a health checkup from 2017 to 2018 in our institution. Participants with alcohol intake exceeding 20 g/day or with other chronic liver diseases were excluded. Fatty liver was detected by ultrasonography. Results: In total, 4310 participants were enrolled, and 28.4% had fatty liver (NAFLD). The prevalence of NAFLD was highest in the diabetes mellitus (DM)-only group than in the dyslipidemia-only or hypertension-only group. The DM-only group was the only group whose prevalence of NAFLD was >50% in the overall study and in males. The prevalence of NAFLD was higher in males than in females in the DM-only, hypertension-only, and dyslipidemia-only groups. The prevalence of NAFLD was >70% in the dyslipidemia and DM combined group. Multivariate analysis showed that gender and HbA1c were the independent factors most strongly associated with NAFLD. The cutoff value for HbA1c by receiver operating characteristic curve analysis was 5.8% (sensitivity, 57.9%; specificity, 72.6%; area under the curve, 0.70). Conclusion: NAFLD was most strongly associated with DM, among the various components of metabolic syndrome. We strongly recommend abdominal ultrasonography to detect NAFLD in patients with an HbA1c of ≥5.8% in general practice and during health checkups.