Changes in Fatty Liver Disease and Incident Diabetes Mellitus in Young Korean Adults

Introduction

This study sought to assess the association between the changes in nonalcoholic fatty liver disease (NAFLD) and risk of type 2 diabetes in young individuals with prediabetes.

Methods

Data from the Korean National Health Insurance System database were collected from 2009 to 2019 and analyzed in 2022. A total of 446,813 young adults aged 20–39 years with prediabetes who underwent two National Health Screening examinations from 2009 to 2012 were followed up. NAFLD was defined as a fatty liver index≥60 without liver disease or history of alcohol abuse. Multivariable Cox proportional hazards regression was used to calculate the HR and CIs for type 2 diabetes according to NAFLD changes.

Results

During a median follow-up of 8.3 years, 26,464 (5.9%) young individuals developed type 2 diabetes. Multivariable adjusted HR of type 2 diabetes according to the NAFLD change was 5.38 (95% CI 5.08–5.70) in individuals with persistent NAFLD when compared to those who never had NAFLD. Even in individuals who were consistently nonobese, resolved NAFLD, new NAFLD, and persistent NAFLD were associated with>3-fold increased risk of type 2 diabetes compared to nonobese individuals without NAFLD. The risk of type 2 diabetes also increased in obese individuals without NAFLD by 2-fold when compared to nonobese individuals without NAFLD.

Conclusions

NAFLD that either existed persistently or ever existed plays a critical role in the development of type 2 diabetes in young adults with or without obesity. Nonobese individuals with NAFLD warrant special attention.