Retinol-binding protein 4 (RBP4) may affects obesity development and the development of obesity-related diseases including insulin resistance, type 2 diabetes, steatohepatitis and cardiovascular disease. This study aims to examine the involvement of RBP4 in patients with diagnosed diabetes, diabetic cardiovascular disease, pre-diabetes (pre-DM) and healthy controls during the progression of T2DM, and to evaluate the ability of RBP4 to predict cases of diabetes with an elevated risk of cardiovascular complications . Along with animal experiment.

A total of 500 Chinese patients admitted to the First Affliated Hospital of Xi'an Jiaotong University (Xi'an, China) between March 2020 and March 2022 were recruited to investigate the RBP4 profles. Peripheral blood samples are drawn at the initial medical examination, in the morning after a fast of at least 8 h, and immediately stored at -80˚C until the sphingolipid measurements were performed.

Blood pressure, WC, hip circumference (HC), body weight and body height were measured by a trained physician. The participants enrolled in the study provided written informed consent.

Inclusion Criteria:

T2DM:

• Fasting plasma glucose (FPG)≥7.0 mmol/l;
• 2 h plasma glucose (2hPG) ≥11.1 mmol/l;
• glycated hemoglobin (HbA1c) level ≥6.5%;
• random plasma glucose ≥11.1 mmol/l plus symptoms of hyperglycemia;
• T2DM diagnosed previously.

Pre-DM was defned as follows:

• FPG ≥5.6-6.9 mmol/l
• 2hPG 7.8-11.0 mmol/l
• HbA1c 5.7-6.4%.

Exclusion Criteria:

• type 1 diabetes
• liver or kidney disorders.

A total of 500 Chinese patients admitted to the First Affliated Hospital of Xi'an Jiaotong University (Xi'an, China) between March 2020 and March 2022 were recruited to investigate the RBP4 profles. The different groups were matched for age, sex and BMI.