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Despite the fact that non-alcoholic fatty liver disease (NAFLD) and its severe clinical forms [non-alcoholic steatohepatitis (NASH) and NASH-cirrhosis] are highly prevalent in the general population, there are no licensed drugs for NAFLD, and lifestyle intervention remains the only treatment accepted by international guidelines. This is despite massive investments in research by pharmaceutical companies. In the presence of type 2 diabetes, novel anti-diabetic drugs offer an opportunity to reduce the burden of NAFLD, by adequate control of glucose and lipid metabolism, also reducing the risk of NASH progression, advanced fibrosis, and finally hepatocellular carcinoma. We extensively reviewed the literature, based either on registration studies, ad hoc randomized studies or real-world data, to define the effectiveness of anti-diabetic drugs in the treatment of NAFLD and prevention of hepatocellular carcinoma (HCC). Metformin provides the best evidence for decreased risk of HCC, pioglitazone was associated with decreased progression to fibrosis, glucagon-like peptide-1 receptor agonists offer a possible opportunity to reduce NAFLD progression coupled with a definite protection for cardiovascular outcomes, and sodium-glucose cotransporter-2 inhibitors are likely to reduce lipid burden, simultaneously reducing the risk of progressive renal and heart failure. For the latter two drug classes, the effects on NAFLD might largely explained by decreased body weight, in keeping with the beneficial effects of intensive lifestyle intervention.

Nonalcoholic fatty liver disease (NAFLD) is defined by hepatic steatosis in the presence of alcohol intake within safe limits, defined by guidelines of scientific associations (usually 20 g or 2 units/day in women, 30 g or 3 units in men). The diagnosis is usually followed by medical counseling of total abstinence, in order to prevent disease progression. This policy has been challenged by epidemiological studies, suggesting that the risk of liver disease and disease progression is lower in modest drinkers than in total abstainers. We revised the literature on the effects of modest alcohol intake on disease burden. Epidemiological data may suffer from several potential biases (recall bias for retrospective analyses, difficulties in the calculation of g/day), limiting their validity. Prospective data suggest that NAFLD patients with regular alcohol intake, although within the safe thresholds, are at higher risk of liver disease progression, including hepatocellular carcinoma; a detrimental effect of modest alcohol drinking is similarly observed in liver disease of viral etiology. Alcohol intake is also a risk factor for extrahepatic cancers, particularly breast, oral, and pharyngeal cancers, with gender difference and no floor effect, which outweigh the possible beneficial effects on cardiovascular system, also derived from retrospective studies. Finally, the negative effects of the calorie content of alcohol on dietary restriction and weight loss, the pivotal intervention to reduce NAFLD burden, should be considered. In summary, the policy of counseling NAFLD patients for alcohol abstinence should be maintained.