<prompt> A 50 year old obese female presented with recurrent candidial urinary infection excessive thirst. She also gives history of frequent night time urination. Which is the first test you will prefer in this patient?HbA1cOral glucose tolerance testPlasma C-peptide levelRandom plasma glucose level  <response>: Given clinical scenario is suggestive of Diabetes mellitus For screening, FBS or HbA1c is recommended. Because the patient has symptoms, a random plasma glucose of 200 mgdL is adequate to diagnose diabetes mellitus. Other criteria include: FBS 126 mgdL HbA1c6.4 2-hour plasma glucose 200 mgdL during an oral glucose tolerance test C-peptide- determine normal cleavage of insulin from its precursor Normal C-peptide level with hypoglycaemia- surreptitious insulin use Low C-peptide level with hyperglycemia- pancreatic failure. 