<prompt> A 42 year old male has strong positive Benedicts test, random blood sugar is 163 mg, fasting blood sugar is 200mg. Next line of investigation is:Urine glucose chaing 5 hourlyOral GTTRepeat benedicts test24 hr urine sugar estimation  <response>: Answer is B Oral GTT: Oral glucose tolerance test Oral GTT should be performed when the diagnosis of diabetes is in doubt The patient in question has a random blood glucose of 163 mgdl which is lower than the required level 200 mgdl to consider diabetes. He however has a fasting blood glucose level of 200mgd1 which is well above the desired level 126 mgdl to consider diabetes. Although fasting blood glucose is the more reliable test for ident5ing DM, and diabetes may be diagnosed with a fasting blood glucose 126mgd1 such diagnosis should not be made if only a single fasting blood glucose meets the criterion. The next best step is either to repeat the test on a different day preferred or perform an oral GTT. As the option of repeating fasting blood glucose is not provided in the question, performing an oral GTT becomes the single best answer of exclusion. Criteria for the diagnosis of diabetes mellitus Symptoms of diabetes plus random blood glucose concentration 11.1 mmolL 200mgdL Fasting plasma glucose 7.0 mmolL 126 mgdL or Two-hour plasma glucose 11.1 mmolL 200 mgdL during an oral glucose tolerance test. Note: In the absence of unequivocal hyperglycemia and acute metabolic decompensation, these criteria should be confirmed by repeat testing on a different day. 