Microbiota is important for immunology, hormonal and metabolic homeostasis in human and could influence on developing diabetes and obesity. Recent studies investigates microbiota by metagenomic sequencing, however, the composite of microbiota and its metabolic role has not been fully determined. Metagenomics and microbiome analysis could early diagnose metabolic disorders and suggest treatment options for metabolic diseases.

In this study, the investigators investigate the composite of microbiota and deduct basic information for treatment models using metagenomic sequencing.

1. Cross-section study: normal/prediabetes/drug naïve type2 diabetes: compare microbiota using metagenomic sequencing among three groups.
2. Observational prospective study: metformin/sodium glucose co-transporter 2 (SGLT2) inhibitor/ezetimibe: compare microbiota using metagenomic sequencing before and after drug treatment.

Inclusion Criteria:

• normal group: body mass index [BMI]<23kg/m2, without diabetes mellitus history
• prediabetes group: fasting blood glucose ≥100 mg/dL and <126 mg/dL or postprandial blood glucose ≥140 mg/dL and <200 mg/dL
• type 2 diabetes according to ADA(American Diabetes Association) guideline (1) fasting blood glucose ≥126 mg/dL, (2) random blood glucose ≥200 mg/dL and with typical diabetes symptoms, (3) glycated hemoglobin A1c ≥6.5% and anti-hypoglycemic drug naive
• patients with type 2 diabetes, metformin monotherapy, SGLT2 inhibitor monotherapy
• patients with dyslipidemia, ezetimibe therapy

Exclusion Criteria:

• inflammatory bowel disease (Crohn's disease, ulcerative colitis)
• history of stomach, small intestine or colon resection operation
• on antibiotics therapy

type 2 diabetes patients with oral hypoglycemic agent/insulin naive