The impact of non-alcoholic fatty liver disease on incident type 2 diabetes mellitus in non-overweight individuals.

BACKGROUND & AIMS: The aim of this study was to evaluate the impact of non-alcoholic fatty liver disease (NAFLD) on incident type 2 diabetes mellitus (T2DM) in non-overweight individuals with NAFLD. METHODS: A population-based retrospective cohort study of 4629 participants who were enrolled in a health check-up programme for more than 10 years. A standardized questionnaire and abdominal ultrasonography were used to diagnose NAFLD. A cut-off point of BMI 23 kg/m(2) was used to define overweight (≥23.0 kg/m(2)) or non-overweight (<23.0 kg/m(2)). The primary outcome was incident T2DM. RESULTS: Over a mean follow-up of 12.8 years, 351 participants (7.6%) developed T2DM. The incidence rate of T2DM was 3.2% in the non-overweight without NAFLD group, 14.4% in the non-overweight with NAFLD group, 8.0% in the overweight without NAFLD group and 26.4% in the overweight with NAFLD group. The adjusted hazard ratios for incident T2DM compared with the non-overweight without NAFLD group were as follows: 3.59 (95% CI: 2.14-5.76) in the non-overweight with NAFLD group, 1.99 (95% CI: 1.47-2.69) in the overweight without NAFLD group and 6.77 (95% CI: 5.17-8.91) in the overweight with NAFLD group. The adjusted hazard ratio in the non-overweight with NAFLD group was significantly higher than that in the overweight without NAFLD group or that in the non-overweight without NAFLD group. CONCLUSIONS: Non-overweight individuals with NAFLD had a high risk of incident T2DM. Diagnosis of NAFLD is important in non-overweight individuals, and therefore it might be necessary to follow their health conditions on a long-term basis after detection of NAFLD.