Association of nonalcoholic fatty liver disease with components of metabolic syndrome according to body mass index in Korean adults.

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease, and its prevalence is much higher in obese individuals. NAFLD is closely related to metabolic syndrome (MetS); however, most concepts about the relationship between NAFLD and MetS have emphasized obesity, although NAFLD is not a rare disease in the non-obese population. In the present study, we aim to determine the association between NAFLD and MetS and to compare this association between non-obese and obese individuals. A total of 29,994 adults who underwent routine comprehensive health evaluations, including abdominal ultrasonography, were selected. We calculated the adjusted prevalence ratios (PRs) for components of MetS (high blood pressure (BP), impaired fasting glucose, low high-density lipoprotein cholesterol (HDL-C), and high triglycerides (TG)) according to NAFLD in non-obese and obese patients. NAFLD was found in 12.6% of non-obese subjects and 50.1% of obese subjects. NAFLD was associated with most components of MetS in both obese and non-obese subjects. However, non-obese NAFLD patients had significantly higher PRs for certain components of MetS than did obese patients, especially among women. Adjusted PRs (95% confidence interval) for components of MetS in non-obese women vs. obese women were as follows: (1) high BP: 1.41 (1.31-1.51) vs. 1.05 (0.89-1.22) (2) impaired fasting glucose: 2.04 (1.95-2.75) vs. 1.37 (1.21-1.53) (3) low HDL-C: 2.00 (1.92-2.08) vs. 1.40 (1.26-1.55), and (4) high TG: 3.36 (3.24-3.47) vs. 1.97 (1.76-2.17). NAFLD was associated with risk for components of MetS, and the association was stronger in non-obese than in obese individuals, especially in women. Therefore, NAFLD should be considered a meaningful predictor of metabolic diseases in the non-obese population.