2.1. Study population and definition

Patients with CAD and T2DM were enrolled between January 2016 and December 2018 from the Department of Cardiology, Shandong Provincial Qianfoshan Hospital, Shandong University, Jinan, Shandong Province, China.

The following criteria were applied for selecting participants: all participants were ≤70 years old with CAD diagnosed through coronary angiography (CAG).

The diagnostic criteria for patients with CAD were as follows: according to the criteria of the World Health Organization and/or CAG, at least 1 of the 3 major coronary arteries or major branches has stenosis ≥50%.^[19]

Diagnosis of T2DM was made if participants experienced one or more of the following: symptoms of diabetes plus casual plasma glucose concentration ≥11.1 mmol/L; fasting plasma glucose ≥7.0 mmol/L; 2-hour post load glucose ≥11.1 mmol/L during an oral glucose tolerance test (OGTT).^[20] Participants need also to have not consumed any lipid-lowering drugs in the previous 3 months.

Patients with severe kidney disease and eGFR ≤30 mL/min/1.73 or with elevated liver transaminase were excluded. Patients with drug or alcohol abuse^[21] were also excluded.

Ethics approval was granted by the Clinical Research Ethics Committee of Shandong Provincial Qianfoshan Hospital (approval number [2015] (S004)). Informed consent was obtained from all participants before inclusion.