This illustration from the Healthsphere Clinic Facebook page compares FBS to a snapshot and HbA1c to a longer-term view. They describe blood sugar over different time periods.
FBS, or fasting blood sugar, measures blood glucose after at least eight hours without food. It reflects glucose at the time the sample is taken. Confirm preparation instructions with the clinic before testing.
HbA1c reflects average blood glucose over approximately the previous two to three months. HbA1c alone usually does not require fasting, but other tests taken at the same visit may do so.
A clinician may choose one or both tests based on your history. Results that do not agree, or conditions affecting red blood cells, may need further assessment. Do not adjust medication yourself.
