Glycated hemoglobin (GHb) measured as HbA1c in diabetic patients, is used to evaluate long-term control of diabetes mellitus, and most accurately reflects the previous 2-3 months of glycemic control. Liver disease is one of the leading causes of death in persons with type 2 diabetes mellitus. Diabetic patients can present with abnormal liver chemistries, from benign nonalcoholic fatty liver disease to severe cirrhosis of the liver. Because liver disease is associated with impaired glucose tolerance and diabetes mellitus, tools are needed to measure long-term glycemic control. In this review we discuss current information on glycated hemoglobin, HbA1c assay methods, attempts to standardize HbA1c assay methods, fructosamine and interferences caused by liver disease. We aim to alert the reader to current problems in determining long-term glycemic control parameters, HbA1c and fructosamine, and describe the measures necessary for proper interpretation of HbA1c.