Fasting blood sugar vs blood sugar after eating

Fasting blood sugar and blood sugar after eating answer different questions. Mixing them in one unlabeled list makes a glucose log hard for you and for a clinician to read.

Fasting

Usually no calories for at least 8 hours. Published screening language often discusses fasting plasma glucose around 70–99 mg/dL (3.9–5.5 mmol/L) for many adults without diabetes — clinic labs, not a phone app, are used for diagnosis (ADA Standards of Care; WHO diabetes criteria pages).

After eating

Post-meal (postprandial) checks are often timed 2 hours from the start of the meal. ADA materials discuss individualized targets; a commonly mentioned 2-hour point for many people with diabetes is below about 180 mg/dL (10 mmol/L). Your target may differ.

How to tag in Blood Snap

Choose fasting, before meal, after meal, or bedtime when you log. That keeps fasting blood sugar levels and after-eating values separable in history and on charts of numbers you entered. The app does not mark a reading as “good sugar levels” or “high glucose.”

Log this in Blood Snap. Same time of day, same tags, then export CSV or PDF. Ask your clinician how to interpret the diary.

Educational information with public guideline citations. Not medical advice and not a diagnosis. Blood Snap is a personal wellness diary — not a medical device, blood pressure machine, glucometer, or CGM. Always follow your clinician's advice.