Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) causes progressive liver fibrosis. Although erythrocyte mean corpuscular volume (MCV) has been shown to have a positive correlation with all-cause mortality, the association between MCV and the development of MASLD has not been fully elucidated. Here, we examined the clinical significance of the association between MCV and MASLD. Methods: A cross-sectional study was carried out in 1009 Japanese individuals (including 186 individuals aged < 60 years and 823 individuals aged ≥ 60 years) with metabolic disorders. The relationships between MCV and noninvasive clinical markers of liver fibrosis, including fibrosis-4 (FIB-4) index, aspartate aminotransferase-to-platelet ratio index (APRI), and non-alcoholic fatty liver disease (NAFLD) fibrosis score (NFS), were statistically evaluated. Results: Using multiple and logistic regression analyses in overall subjects, it was found that MCV was positively and independently associated with the values of FIB-4 index, APRI, NFS, and the prevalence of liver fibrosis defined by each index. However, the associations between the MCV value and MASLD indices were found to be positive in subjects aged ≥ 60 years but not in those aged < 60 years. Conclusions: MCV might be a simple and useful biomarker for the development of MASLD in the elderly.

Background/Objectives: Visit-to-visit glycated hemoglobin A1c (HbA1c) variability is associated with cardiovascular diseases (CVDs) and all-cause mortality, independent of mean HbA1c levels. Metabolic dysfunction–associated steatotic liver disease (MASLD) is associated with CVDs and mortality. We aimed to clarify the association between annual HbA1c variability and MASLD development in individuals with type 2 diabetes (T2D). Methods: A retrospective cohort study was conducted in 402 Japanese patients (219 men, 183 women) with T2D. The participants’ HbA1c levels were measured every 2 months, and their HbA1c coefficient of variation (HbA1c-CV) was calculated from the HbA1c in the past year. We statistically evaluated the association between HbA1c-CV and noninvasive clinical indices of MASLD, including the hepatic steatosis index (HSI), fibrosis-4 (FIB-4) index, aspartate aminotransferase-to-platelet ratio index (APRI), and non-alcoholic fatty liver disease fibrosis score (NFS). Results: Multiple regression analysis of clinical variables and each MASLD index showed that all liver fibrosis indices, including the FIB-4 index (p < 0.001), APRI (p = 0.005), and NFS (p < 0.001), were positively correlated with HbA1c-CV, whereas the HSI was not (p = 0.148). These associations remained even after adjusting for the medications used in the participants. Conclusions: The development of liver fibrosis, estimated using noninvasive blood biochemical indices, is independently and positively associated with annual HbA1c-CV in individuals with T2D. This result suggests that a comprehensive approach, including early MASLD risk stratification, may be beneficial for optimal diabetes management.