You went for a walk after dinner, and later your reading looked different than you expected. Was it the walk? The meal? Something else? It is hard to tell from memory alone, and that is where a simple log can help.
An exercise and blood sugar log is just a place to write down what you did, how hard it felt, and any glucose readings your care team has asked you to check. Over a few weeks, these notes can help you and your healthcare team see your own patterns. This guide covers what to record, a sample log you can copy, and how to share what you find.
Why log activity alongside your glucose readings
Physical activity is an important part of diabetes care, and it can affect blood glucose in more than one way. According to the American Diabetes Association's position statement on physical activity, activity often lowers glucose during exercise and for a period afterward. For some people, short bursts of very intense exercise can raise glucose for a while instead.
How your body responds can depend on the type of activity, how long and how hard you exercise, when you last ate, your medications, and more. Everyone's response is different, and yours may change from day to day. Writing things down helps you learn what is typical for you, rather than relying on general rules.
A log also gives your care team real information to work with. Instead of trying to recall last Tuesday's workout, you can show them exactly what happened.
What to record in your exercise and blood sugar log
You do not need to track everything. Pick the details that are most useful to you and your care team, and keep it simple enough that you will actually do it.
The activity
- Type: walking, cycling, strength training, gardening, swimming, dancing, and so on.
- Duration: how many minutes you were active.
- Intensity: how hard it felt (see below).
- Time of day and timing around meals: for example, "30 minutes after lunch" or "before breakfast."
How hard it felt: the talk test and RPE
You do not need special equipment to rate intensity. Two simple tools work well:
- The talk test. During light activity, you can talk and even sing. At a moderate level, you can talk but not sing. During vigorous activity, you can only say a few words before needing a breath.
- Rating of perceived exertion (RPE). Rate how hard the activity feels on a scale of 0 to 10, where 0 is sitting still and 10 is your hardest possible effort. Moderate activity is often around 5 to 6, and vigorous activity around 7 to 8.
Using the same scale each time makes your notes easier to compare.
Readings, food, and how you felt
- Glucose readings before and after, if your care team has asked you to check around activity. If you use a CGM, you might note the reading and trend arrow.
- Food and snacks: what you ate before, during, or after, and roughly when.
- Symptoms: shakiness, sweating, dizziness, unusual tiredness, or anything else you noticed.
- Any lows: when it happened, what you did, and how long it took to feel better.
- Other notes: poor sleep, stress, illness, hot weather, or a change in routine.
A sample exercise log
Here is one simple way to lay out your log. The rows below are filled in with placeholder examples to show the format, not real or recommended numbers. Leave the reading columns blank if you are not checking around activity.
| Date and time | Activity | Minutes | Intensity (talk test / RPE) | Timing vs. meal | Reading before | Reading after | Food or snacks | Symptoms / notes |
|---|---|---|---|---|---|---|---|---|
| Mon, 6:45 pm | Brisk walk | 25 | Can talk, not sing / 5 | 30 min after dinner | ___ mg/dL | ___ mg/dL | None | Felt good |
| Wed, 7:30 am | Strength training (bands) | 20 | Moderate / 6 | Before breakfast | ___ mg/dL | ___ mg/dL | Breakfast after | Legs tired |
| Sat, 10:00 am | Yard work | 60 | Light to moderate / 4 | 2 hours after breakfast | ___ mg/dL | ___ mg/dL | Water, small snack | Hot day; felt shaky later, followed my low plan |
A notebook, a spreadsheet, a phone app, or a printed planner all work. If you already keep a daily planner, you can add an activity column to it. Our guide on how to use a daily diabetes planner shows how to fit this in.
Spotting patterns (and what to do with them)
After a couple of weeks, look back over your notes. You might notice things like:
- Readings after an evening walk tend to look different from readings after a morning workout.
- You feel more tired or shaky on days you exercise before eating.
- Strength training days and walking days seem to affect you differently.
- Lows show up hours after longer or harder sessions.
Treat these as observations to discuss, not instructions to act on by yourself. A pattern in your log is a great conversation starter, but it is not a reason to change your medication, insulin, or eating plan on your own. Your care team can help you understand what the pattern means and whether anything should change.
A note on delayed lows
If you take insulin or a sulfonylurea, activity can raise your risk of low blood sugar (hypoglycemia), and lows can sometimes happen hours after exercise, including overnight. This is one reason logging is so useful for people on these medicines.
Low blood sugar can cause shakiness, sweating, a fast heartbeat, hunger, irritability, dizziness, or confusion. If you notice these symptoms, follow the plan your care team has given you. A severe low is an emergency. Ask your care team whether you should carry fast-acting carbohydrate during activity, and when and how often to check your glucose before, during, and after exercise.
Sharing your log with your care team
Bring your log, or a summary, to your next appointment. You do not need to present every entry. Instead, note two or three patterns or questions, such as "I tend to feel shaky a few hours after longer walks. Is that something we should plan for?"
Our guide on how to review your logs before an appointment walks through how to turn weeks of notes into a short, useful summary.
If you are just getting started with activity, our guides to starting a walking routine and beginner strength training are good places to begin, and both pair well with a simple log.
When to talk to your care team
Check with your healthcare team before starting a new activity routine, especially if you take insulin or a sulfonylurea, or have heart disease, eye disease (retinopathy), or nerve damage or other problems with your feet. Reach out sooner if your log shows frequent lows or highs around activity, lows that happen hours later or overnight, or symptoms like chest pain, dizziness, or unusual shortness of breath during exercise. They can help you decide what to check, when, and whether any changes to your plan make sense.
A few lines a day is all it takes. Over time, your log becomes a clear picture of how movement fits into your life with diabetes.
