Nonalcoholic fatty liver disease is a risk factor for glucose intolerance onset in men regardless of alanine aminotransferase status

Introduction Fatty liver disease (FLD) is a surrogate condition for glucose intolerance development. FLD may involve normal or abnormal liver enzyme levels. Whether FLD is a risk factor for glucose intolerance, regardless of liver enzyme levels, remains unknown. We assessed relationships between the development of impaired fasting glucose (IFG) and FLD, liver enzyme abnormalities, and alcohol consumption. Materials and Methods We retrospectively evaluated 8,664 participants with more than two annual health check-ups. Participants were classified according to sex, alcohol consumption, alanine aminotransferase (ALT) levels, and fatty liver status. Results In univariate analyses, IFG onset among men was related to normal or high ALT levels with FLD in the nonalcoholic and alcoholic groups (P-trend < 0.01). In multivariate analyses, IFG onset among nonalcoholic men was associated with normal or high ALT levels with FLD, independent of potential confounding factors (P-trend < 0.01). However, IFG onset was non-independently associated with any condition among alcoholic men. In univariate analyses, IFG onset among women was related to normal or high ALT levels with FLD in the nonalcoholic group (P-trend < 0.01) and high ALT levels with FLD in the alcoholic group (P-trend < 0.05). In multivariate analyses, IFG onset was independently associated with only normal ALT levels in nonalcoholic FLD women. Conclusions Among nonalcoholic men and women, FLD was a risk factor for IFG onset, including normal ALT concentrations. Care is needed for individuals with nonalcoholic FLD, regardless of liver injury, possibly helping reduce glucose intolerance risk.