What should you know about type 2 diabetes fasting glucose?

Fasting glucose gives a snapshot of glucose after the overnight or instructed fasting period. It can be influenced by late meals, illness, stress, sleep, alcohol, activity and medicines. One unexpected result does not describe your usual control or confirm that treatment has failed.

Your clinician may compare fasting readings with readings after meals and a longer-term test. Targets differ between people because age, pregnancy, kidney health, medicines and the risk of hypoglycaemia all matter.

Follow the same testing instructions each time, wash and dry your hands, and record the time, fasting period, medicines, illness and unusual meals. Do not deliberately skip prescribed medicine or food unless your clinician gives fasting instructions for a specific test.

Look for patterns over several days rather than reacting to a single result. Share the record if fasting readings are repeatedly outside your agreed range, particularly after a medicine change or illness.

Contact your diabetes team for repeated readings outside your agreed range or symptoms such as unusual thirst, frequent urination or blurred vision. Get urgent help for vomiting, severe dehydration, confusion, fainting, deep or rapid breathing, or marked weakness, especially when glucose is very high or very low.

Ask how long to fast, when to test, what range is personal to you, which medicines to take before testing, and what action to take when a reading is unexpectedly high or low.