This study is designed to compare the serum sphingolipidomic analyses in healthy, pre-diabetic and diabetic subjects. age, sex and BMI are matched among these three groups. As ceramide, sphingosine, sphingosine-1-phosphate and sphinganine are involved in inflammation, immunity and cancer, investigators proposed a hypothesis that sphingosine-1-phosphate and other sphingolipids may be associated with the progress of type 2 diabetes. sphingolipids may be a biomarker for diabetes.

The first purpose of this study is to determine whether serum sphingolipid metabolites associate significantly with the weight among type 2 diabetes. 60 patients with diagnosed type 2 diabetes will be recruited. The serum concentrations of sphingolipid metabolites of 20 type 2 diabetic patients with obesity will be compared to age- and sex-matched series of 40 type 2 patients without obesity.

The second purpose of this study is to determine whether serum sphingolipid metabolites associate significantly with the process and severity of type 2 diabetes. The serum concentrations of sphingolipid metabolites of 20 subjects with type 2 diabetes will be compared to age-, sex- and BMI-matched series of healthy and pre-diabetic subjects. Investigators speculate that the serum concentration of sphingolipid metabolites are positively related with the progression of diabetes. In order to discover why serum sphingolipid metabolites correlates with the progression of diabetes, detailed information on HbA1c, duration of diabetes history and insulin resistance defined by homeostatic model assessment (HOMA-IR) will be analysed. These three parameters may affect the serum concentrations of sphingolipid metabolites.

Inclusion Criteria:

• clinical diagnosis of diabetes mellitus, type 2
• clinical diagnosis of prediabetic status
• older than 18 and younger than 90 years-old
• clinical diagnosis of insulin-resistance
• clinical diagnosis of newly onset of diabetes mellitus, type 2
• those who are willing to participate in the trial and sign the consent form

Exclusion Criteria:

• any cardiovascular disease (myocardial infarction, heart failure, cerebrovascular accident)
• missing information of BMI
• sever liver, kidney dysfunction
• sever pancreatitis or those who received pancreatectomy
• on medications of hormone, immunosuppressive therapy or drugs that may affect the bioactivity or concentration of sphingolipids (e.g. asprin )
• patients on pregnancy
• sever systematic diseases including carcinoma, mental disorder, sever anemia et al.

subjects undergoing oral glucose tolerance test and hospitalized type 2 diabetic patients in the Dpartment of Endocrinology in the First Affiliated Hospital of Xi'an Jiaotong Unversity are collected.

healthy subjects undergoing routine physical exam in the department of medical examination center, First Affiliated Hospital of Xi'an Jiaotong Unversity are recruited