This is a clinical cohort study to assess disease progression by baseline pathophysiology - insulin resistance and insulin secretion. A total 2000 healthy individuals will be screened through a clinical questionnaire and physical examination to exclude chronic disease/ drug intake. All the individuals will undergo oral glucose tolerance test. individuals with 2 hour glucose more between 140-199 mg/dl will be considered to have prediabetes and those individuals with 2 hour glucose less than 140mg/dl will be considered controls.Total 200 prediabetc and 50 healthy controls will be recruited in year 1.After obtaining written consent form, participant will provide 3 aliquots of 5ml whole blood, one will be used for biochemical fasting assay (fasting C-peptide, glucagon, somatostatin, polypeptide levels, lipids, liver function test, and HOMA IR, HOMA S, HbA1c) and other 2 aliquots will be stored at -80⁰C. Individuals who are matched for age, gender, and BMI will return for clamp study. Hyperglycaemic clamps studies will be conducted on these 250 individuals and will be carefully followed to assess disease progression by baseline pathophysiology (insulin secretion and insulin resistance). In addition, all individuals screened for the study will have oral glucose tolerance (2hr-OGTT) and bio specimens stored for future validation. The hyperglycaemic clamp study will be repeated on the pre-DM and control individuals at the end of 3 years and 5 years to measure the changes in insulin secretion level. Additionally, biomarkeres identified in the islet OMICS study will be validated in the clinical cohort to assess if any of these markers correlate with insulin secretion