A blood sugar log is a dated list of glucose readings with the context around them. The number alone is hard to use. The same 180 mg/dL means different things fasting, two hours after a large meal, or during illness.
Fields that make a reading useful
- Date and time
- The reading and the unit your meter uses (mg/dL or mmol/L)
- Relation to food: fasting, before a meal, or about one to two hours after a meal
- Diabetes medicine or insulin taken, if that applies to you
- A short note on the meal, exercise, illness, or a steroid dose
- Symptoms: shakiness, sweating, confusion, or none
How often
There is no single schedule for every person. People on insulin are often asked to check more often than people managed with diet alone. Your clinician sets both the times and the target range. Write that target at the top of the log so each row has a comparison. Do not copy another person’s targets from the internet.
If you use a continuous glucose monitor, the log still helps: mark meals, medicine, and symptoms so the curve has labels. Bring either the export or a PDF to the visit instead of reading numbers from memory.
Very high readings with vomiting, deep breathing, or confusion, and very low readings you cannot treat yourself, are urgent. Follow the sick-day plan you were given, or seek emergency care.