Fasting Glucose

Fasting Plasma Glucose

Fasting glucose measures the sugar in your blood after at least eight hours without calories. It helps check how your body manages blood sugar when you have not recently eaten.

Try your Fasting Glucose result.

A quick one-marker check. Vita can score it better once it sees the full lab report around it.

What does a high fasting result mean?

A high result can mean your body is not keeping blood sugar within the expected fasting level. It can suggest prediabetes or diabetes, but a diagnosis usually needs confirmation. Illness and some medicines can also raise it.

Adult diagnostic thresholds

Low glucose: Below 70 mg/dL (3.9 mmol/L); needs prompt attention
Below the prediabetes threshold: 70 to below 100 mg/dL (3.9 to below 5.6 mmol/L)
Prediabetes range: 100–125 mg/dL (5.6–6.9 mmol/L)
Diabetes range: 126 mg/dL or more (7.0 mmol/L or more)

These ADA thresholds apply to a fasting laboratory blood test in non-pregnant adults. They are diagnostic decision points, not treatment targets. A result in the diabetes range is usually checked again unless other findings establish the diagnosis.

Sources: NIDDK (NIH); NIDDK (NIH)

What can change this result?

What can raise it

Eating or drinking calories during the required fasting period.
Illness, stress or medicines such as steroids.
Insulin resistance or diabetes, which can keep glucose high even without eating.

What can help over time

Choosing more fiber-rich foods and fewer sugary drinks.
Regular activity and managing excess weight, where appropriate.
Following a diabetes treatment plan if you have one.

Do not fast longer or change medication to get a lower reading. Too much diabetes medicine or a missed meal can cause low glucose, which also needs attention.

What should I do next?

Confirm how long you fasted and tell your clinician about illness or medication changes.
Ask whether a repeat fasting test or HbA1c would clarify the result.
If you feel shaky, sweaty or confused with a low glucose reading, seek prompt help; severe confusion, seizures or fainting need emergency care.

How this test works

Your liver releases glucose between meals. Insulin helps regulate that release and helps cells use glucose. A fasting test checks this balance at a single point in time; HbA1c reflects a longer period.