One reading is a moment. A log is a story. A single glucose reading tells you about one moment, while a record kept the same way over days and weeks can show you something a single number cannot. Here is what published guidance says about keeping a blood glucose log: why it is worth doing, what to write down, how to keep it, and how it can be used at an appointment. This is general information from the sources listed at the end, not advice for your situation. How often you check is a question for your own care team.
Why a log is worth keeping
Test results may help you and your health care team make changes to your meal plan, physical activity level and diabetes medicines, and may help you understand how certain foods affect your glucose [1]. Monitoring helps you figure out what affects your numbers and find patterns [2]. One source goes further and calls the logging of your results vital [3].
What to write down with each reading
A useful entry has a few parts:
- Date and time and the result. The date and time you checked, and the result [1].
- What you ate or did. What you ate or what physical activity you did that day [1]. Food, activity and stress are examples of factors to note [3], along with anything else that might have affected your reading [2].
- When it was taken relative to a meal. Targets differ by timing [3], so a reading is easier to interpret when it is labelled fasting, before a meal, after a meal or random. See the post on fasting, post-meal and random readings.
| Date and time | Result | Timing | Note |
|---|---|---|---|
| Mon 7:10 am | 104 mg/dL | Fasting | Before breakfast |
| Mon 1:35 pm | 131 mg/dL | After lunch | Sandwich, short walk |
| Tue 7:05 am | 98 mg/dL | Fasting | Before breakfast |
Paper, spreadsheet or app
The format is up to you. You can use a chart or a smartphone app to keep track [1]. A handwritten log works if you do not use a phone, and most meters save your results for you and your care team to review, with some syncing to a phone app [2].
Why patterns say more than one number
One reading is a moment. Monitoring helps you find patterns [2]. Over days, a record can show whether highs or lows tend to cluster around certain meals, activities or times of day. With a continuous glucose monitor, you can review changes over hours or days and spot trends [4]. The same logic applies to the longer view: a single HbA1c result is a snapshot of a longer period (see the HbA1c post).
Bringing it to appointments
The advice in these sources is to take your record with you when you visit your health care team [1], and to ask your team about the best way to check your glucose and how often to check it [1]; your doctor will tell you when and how often to check [2]. A log does not replace that conversation. It gives the conversation something concrete to work from.
Sources
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Managing Diabetes.
- Centers for Disease Control and Prevention, Monitoring Your Blood Sugar.
- American Diabetes Association, Check Your Blood Glucose.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Continuous Glucose Monitoring.
We made Steadion, an iPhone tracker for people with diabetes or prediabetes. In it you can log a fingerstick reading by hand, or photograph your meter and let Steadion read the number off it. You confirm the number before it saves. Readings save back to Apple Health, and trend charts show them over time. Learn more at steadion.fit.