Association between nonalcoholic fatty liver disease and incident diabetes mellitus among Japanese: a retrospective cohort study using propensity score matching

Abstract Background Previous studies have demonstrated that nonalcoholic fatty liver disease (NAFLD) is a significant risk factor for diabetes mellitus (DM). However, these studies did not completely determine the relationship between NAFLD and DM due to unbalanced confounding factors. The propensity score (PS) is the conditional probability of having a particular exposure, given a set of baseline measured covariates. Propensity score matching (PSM) analysis could minimise the effects of potential confounders. Thus, this study aimed to use PSM analysis to explore the association between NAFLD and DM in a large Japanese cohort. Methods This retrospective PSM cohort study was performed on 14,280 Japanese participants without DM at baseline in Murakami Memorial Hospital between 2004 and 2015. The independent variable was NAFLD at baseline, and the outcome was the incidence of DM during follow-up. One-to-one PSM revealed 1671 participants with and without NAFLD. A doubly robust estimation method was applied to verify the correlation between NAFLD and DM. Results The risk of developing DM in participants with NAFLD increased by 98% according to the PSM analysis (HR = 1.98, 95% confidence interval [CI]: 1.41–2.80, P