Non-alcoholic fatty liver disease: causes, diagnosis, cardiometabolic consequences, and treatment strategies

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing worldwide. In some patients with NAFLD, isolated steatosis can progress to advanced stages with non-alcoholic steatohepatitis (NASH) and fibrosis, increasing the risk of cirrhosis and hepatocellular carcinoma. Furthermore, NAFLD is believed to be involved in the pathogenesis of common disorders such as type 2 diabetes and cardiovascular disease. In this Review, we highlight novel concepts related to diagnosis, risk prediction, and treatment of NAFLD. First, because NAFLD is a heterogeneous disease, the advanced stages of which seem to be strongly affected by comorbidities such as insulin resistance and type 2 diabetes, early use of reliable, non-invasive diagnostic tools is needed, particularly in patients with insulin resistance or diabetes, to allow the identification of patients at different disease stages. Second, although the strongest genetic risk alleles for NAFLD (ie, the 148Met allele in PNPLA3 and the 167Lys allele in TM6SF2) are associated with increased liver fat content and progression to NASH and cirrhosis, these alleles are also unexpectedly associated with an apparent protection from cardiovascular disease. If consistent across diverse populations, this discordance in NAFLD-related risk prediction between hepatic and extrahepatic disease might need to be accounted for in the management of NAFLD. Third, drug treatments assessed in NAFLD seem to differ with respect to cardiometabolic and antifibrotic efficacy, suggesting the need to better identify and tailor the most appropriate treatment approach, or to use a combination of approaches. These emerging concepts could contribute to the development of a multidisciplinary approach for endocrinologists and hepatologists working together in the management of NAFLD.