 Cirrhosis and advanced liver disease have been associated with an increased risk for hyperglycemia and type 2 diabetes mellitus T2DM. The diagnostic yield of common tests used to define diabetes and insulin resistance in the general population differs significantly from the one observed in patients with liver disease. Glycosylated hemoglobin A1c HbA1c, a reliable test to assess chronic glycemia and recommended both for the diagnosis and monitoring of T2DM, is neither accurate nor reliable in patients with cirrhosis. A validation study has not been performed to define its true usefulness in the setting of cirrhosis. The study aims to determine the level of HbA1c that better corresponds to the diagnosis of T2DM - as determined by an oral glucose tolerance test OGTT - and to correlate the levels of HbA1c with the average glucose over a 12-week period in patients with cirrhosis and known T2DM, in cirrhotic patients with different degrees of liver impairment as compared to patients with T2DM and no liver disease. 