Objective:To investigate the status and related factors of fasting hyperglycemia in hospitalized patients with diabetes. Methods:Total 1055 diabetic patients who underwent continuous glucose monitoring from Jan.2013 to Dec. 2014 in five hospitals were enrolled in this study. Sex,age,type of diabetes,duration,body mass index(BMI),blood pressure,glycosylated hemoglobin (HbA1c),blood lipid,urinary albumin,macroangiopathy and so on were collected to analyze the risk factors. Results:Totally 83.9% of diabetic patients had fasting hyperglycemia,of which 75.2% was poor glucose control throughout the day,15.4% was dawn phenomenon and 9.4% was Somogyi effect. The incidence of Somogyi effect in type 1 diabetes patients was significantly higher than that in type 2,and the incidence of poor glucose control throughout the day in type 2 diabetes patients was significantly higher than that of type 1. The one-way ANOVA analysis results showed that there were significantly differences of age,type,duration,blood pressure,blood lipid between dawn phenomenon group,Somogyi effect group,and poor glucose control throughout the day group (P < 0.05). The binary logistic regression analysis results showed that older,longer duration,higher TG,and higher LDL-C were more likely to occur in poor glucose control throughout the day (P < 0.05). Patients with younger age,shorter duration,higher systolic blood pressure or higher TC were more likely to have dawn phenomenon (P < 0.05). Lower TC and TG were more prone to Somogyi effect (P < 0.05). Conclusion:Fasting hyperglycemia was a common phenomenon among hospitalized patients with diabetes. The causes in sequence were poor glucose control,dawn phenomenon and Somogyi effect. Type 1 diabetes patients were more likely to have Somogyi effect. Age,duration,TC,and LDL-C were risk factors for poor glucose control throughout the day; Age,duration,systolic blood pressure and TC were risk factors for dawn phenomenon; TC,TG were risk factors for Somogyi effect.