Blood Sugar Fasting Test

Blood sugar fasting test is done to diagnose patients suspected to be suffering from diabetes or hypoglycemia. This test can be done in fasting state, post glucose intake (post-prandial) or randomly. It is also done to diagnose diabetes during pregnancy (gestational diabetes).  Though HbA1c is a preferred test to diagnose diabetes due to several advantages but blood glucose estimation is the test of choice for diagnosis in patients of hemoglobin variants, sickle cell anemia, pregnancy (2nd & 3rd trimester), postpartum (immediately after pregnancy), G6PD deficiency, HIV, hemodialysis, recent blood loss, transfusion or erythropoeitin therapy. In the above mentioned cases HbA1c is not used to diagnose diabetes

Blood sugar fasting test measures blood glucose levels in plasma of the patient

Blood sugar fasting test requires a blood sample. A tourniquet (elastic) band is placed tightly on the upper arm. The patient is then asked to make a fist. This helps in the build-up of blood filling the veins. The skin is disinfected before needle insertion and the blood sample is collected in vacutainer.

Result values considered normal or abnormal differ basis type of test done i.e., random, fasting, post-prandial
Fasting blood sugar: 
Hypoglycemia: <70 mg/ dL; Normal: 70-99 mg/dL; Impaired: 100-125 mg/ dL; Diabetes: 126 and above
Post-prandial/ Random:
Normal: 139 mg/ dL and less; Impaired: 140-199 mg/ dL; Diabetes: 200 and above