A total of 3802 participants who were hospitalized by the ward and outpatient of digestive department of Putuo Hospital Affiated to Shanghai University of Traditional Chinese Medicine were enrolled consecutively and separately between January 2019 and December 2020.

According to the guidelines for diagnosis and treatment of nonalcoholic fatty liver disease (2018) [20] formulated by the National Workship on Fatty Liver and Alcoholic Liver Disease and Chinese Society on Hepatology, the diagnosis of early-stage NAFLD was based on the detection of steatosis by abdominal ultrasonography. Only if three deputy director physicians make the same diagnosis could the patient be included.

The following exclusion criteria were used: (1) had a history of liver diseases other than NAFLD, including viral hepatitis, cirrhosis, liver cancer, autoimmune liver disease, alcoholic liver disease, hereditary liver disease, etc.; (2) excessive alcohol consumption (≥ 210 g/week for men, ≥ 140 g/week for women); (3) were taking medications that can affect metabolism or cause liver damage,; (4) had been diagnosed with diabetes, had received or were undergoing hypoglycemic drugs or insulin treatment; (5) had severe heart disease (myocardial infarction, heart failure and / or severe arrhythmia); (6) had severe infections and severe trauma; (7) pregnant or breastfeeding women; (8) had thyroid diseases, including hyperthyroidism and hypothyroidism.

In the end, 112 subjects (68 males and 44 females, aged ≥ 18 years) met the diagnosis criteria of the research (Fig. 1). The control group included 112 healthy people. This research was conducted in accordance with the Declaration of Helsinki to protect the health and rights of the participants. Written informed consent was obtained from each participant. The study protocol was approved by the Medical Ethics Committee of the Putuo Hospital Affiated to Shanghai University of traditional Chinese Medicine (Ethics approval number was PTEC-A-2018–49-1).

Flowchart of the study