The global epidemiology of NAFLD and NASH in patients with type 2 diabetes: A systematic review and meta-analysis

Background & Aims

Although non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH) and NASH with advanced fibrosis are closely associated with type 2 diabetes mellitus (T2DM), their global prevalence rates have not been well described. Our aim was to estimate the prevalence of NAFLD, NASH, and advanced fibrosis among patients with T2DM, by regions of the world.

Methods

We searched for terms including NAFLD, NASH and T2DM in studies published from January 1989 to September 2018, using PubMed, Ovid MEDLINE®, EMBASE and Web of Science. Strict exclusion criteria were applied. Regional and global mean prevalence weighted by population size in each country were estimated and pooled using random-effects meta-analysis. Potential sources of heterogeneity were investigated using stratified meta-analysis and meta-regression.

Results

Among 80 studies from 20 countries that met our inclusion criteria, there were 49,419 individuals with T2DM (mean age 58.5 years, mean body mass index 27.9 kg/m², and males 52.9%). The global prevalence of NAFLD among patients with T2DM was 55.5% (95% CI 47.3–63.7). Studies from Europe reported the highest prevalence (68.0% [62.1–73.0%]). Among 10 studies that estimated the prevalence of NASH, the global prevalence of NASH among individuals with T2DM was 37.3% (95% CI 24.7–50.0%). Seven studies estimated the prevalence of advanced fibrosis in patients with NAFLD and T2DM to be 17.0% (95% CI 7.2–34.8). Meta-regression models showed that geographic region and mean age (p <0.5) were associated with the prevalence of NAFLD, jointly accounting for 63.9% of the heterogeneity.

Conclusions

This study provides the global prevalence rates for NAFLD, NASH, and advanced fibrosis in patients with T2DM. These data can be used to estimate the clinical and economic burden of NASH in patients with T2DM around the world.

Lay summary

Non-alcoholic fatty liver disease (NAFLD) is now recognized as the most prevalent chronic liver disease worldwide. Type 2 diabetes mellitus (T2DM) is an important risk factor for NAFLD. Additionally, T2DM seems to accelerate the progression of liver disease in NAFLD. Despite the high prevalence and serious clinical implications of NAFLD in patients with T2DM, it is usually overlooked in clinical practice. This meta‐analysis provides evidence of the high prevalence of NAFLD and NASH in patients with T2DM. In this context, increasing awareness about the importance of NAFLD in patients with T2DM among all important stakeholders (primary care physicians, specialists, and health policy makers) must be prioritized.