Metabolic significance of nonalcoholic fatty liver disease in nonobese, nondiabetic adults.

Background: Obesity and type 2 diabetes are well-known risk factors for the development of nonalcoholic fatty liver disease (NAFLD). However, NAFLD is not rare in nonobese, nondiabetic adults. The aim of this study was to evaluate the metabolic significance of NAFLD in nonobese, nondiabetic adults.

Methods: This study examined 768 nonobese (body mass index [BMI] [calculated as weight in kilograms divided by the square of height in meters], > or =18.5 and <30) (460 normal-weight and 308 overweight subjects), nondiabetic individuals older than 30 years who participated in a medical checkup. All the subjects had negative serologic findings for hepatitis B and C viruses and had an alcohol intake less than 140 g/wk. A standard interview, anthropometrics, a biochemical study, and abdominal ultrasonography were conducted.

Results: The prevalence of NAFLD in the enrolled subjects was 23.4%. In the normal-weight (BMI, > or =18.5 and <25) and overweight (BMI, > or =25 and <30) groups, NAFLD was a significant predictor of insulin resistance and other metabolic disorders, including hypertriglyceridemia and hyperuricemia. The odds ratio of the metabolic disorders in subjects with NAFLD compared with those without NAFLD in the normal-weight group was higher than that in the overweight group. Multiple logistic regression analysis showed that sex, waist circumference, triglyceride level, and insulin resistance were independently associated with NAFLD in the normal-weight group.

Conclusions: Nonalcoholic fatty liver disease is closely associated with metabolic disorders, even in nonobese, nondiabetic subjects. Nonalcoholic fatty liver disease can be considered an early predictor of metabolic disorders, particularly in the normal-weight population.