Hey Swati,
Acceptable blood sugar range on waking up with an empty stomach should be normally between 80 to 120 mg/dl.
Acceptable blood sugar range, two hours after having food should be between 120 to 160 mg/dl
and Acceptable blood sugar range during bedtime should be between 100 to 140 mg/dl. Any variations from the above mentioned value is suggestive of diabetes, if the value of an individual's blood sugar tends to be more than the upper limit. Repeated blood sugar test is necessary to confirm diabetes.