A stubborn morning high or a baffling evening low may raise questions that, without a logbook, are hard to answer. Whether paper or electronic, a logbook provides a place to record blood glucose numbers, foods and drinks you’ve had, carbohydrate counts, physical activity, and other aspects of daily life that can affect your diabetes management.
A logbook can help you and your health care provider figure out what eating plan, exercise, and medications are best for your blood glucose control. But it only works if you know how to make sense of your numbers. Here are experts’ tips on how to make your logbook tell you what you want to know.
1. Before and After
If you measure blood glucose levels before and after eating a meal, working out, or taking a dose of mealtime insulin, a logbook can help you actually see how things you do affect blood glucose. “I truly think that monitoring is the key to successful blood sugar control,” says Marlene Bedrich, RN, MS, BC-ADM, CDE, a program coordinator at the University of California–San Francisco’s Diabetes Teaching Center. “The only way it really works is if you can see cause and effect.”
Without the “before” test, the “after” test is less meaningful, because you don’t know what your starting level was. With meals and snacks, you test before and about two hours after your first bite of food. And some people may want to do extra tests around exercise—before, during, and immediately after—to check for hypoglycemia (low blood glucose). In fact, exercise can have lowering effects on your blood glucose for up to 24 hours.
2. A Matter of Degree
Not everyone with diabetes is going to get the same benefits from day-in, day-out logging. Both Bedrich and Stacey O’Donnell, MS, RN, CNL, CDE, a nurse educator at the Joslin Diabetes Center in Boston, recommend coming up with a plan that will give you the information you need to stay healthy without blowing a gasket. “Logging every day is hard and time consuming. That’s why most people can’t or won’t do it,” O’Donnell says. “I want to make it easier for them.”
People who take insulin, particularly mealtime insulin, have more to gain from regular logging. People with type 2 diabetes who take oral meds or injectables other than insulin may be better off logging more selectively—for example, taking before-and-after blood glucose tests for just one meal a day on occasion. Test around breakfast on one day, lunch the next, and then dinner after that. This will give you an idea of what’s happening in response to what you eat at certain times, without requiring six or more strips in a single day. You may have to save up strips or buy some out-of-pocket to do this type of paired testing.
3. Mark the Meds
Even if you don’t use a logbook every day, it may be a good idea to track blood glucose levels for a couple of weeks when starting a new medication, says O’Donnell, to see how well it’s working. “Those might be periods of time where logging would be beneficial for the patient and the provider.”
Make sure to note when and, in the case of variable doses, how much medication you take during the day. For example, marking down insulin doses at mealtime is important, says Bedrich, but so is noting your long-acting insulin dose or your basal pump rate. That way, “you get the whole timeline,” she says. One tip she offers is that it’s best to log an insulin dose right after taking it, because you may not remember later how much you took.
4. Time to Eat
What you put in your mouth is a big source of blood glucose variation from day to day. To see how food affects your levels, you’ll want to mark down the type and amount of food and calculate the number of carbohydrate grams you eat and drink throughout the day, says O’Donnell. If you don’t use carb counting but rely on the “plate method” or some other eating plan, the type and amount of food are the important things to note.
The payoff comes when you see how various types of food or a certain number of carb grams affect your blood glucose. For example, check before and after breakfast to see if cereal and milk raise your blood glucose differently than whole-grain toast and scrambled egg whites do. For mealtime insulin users, seeing the cause and effect of what you eat and drink helps you fine-tune your personal carb-to-insulin ratio. “It can be different depending on the time of day and the type of medications you’re on,” says Bedrich. “When you test, it can help to determine if the ratio is right or if you counted carbs right.”
5. Workout Wise
Whether you lift weights, swim, walk, or do yoga can affect blood glucose, so making note of what type of physical activity you engage in and for how long can help you figure out an activity’s influence on blood glucose levels. O’Donnell adds that “when people exercise can have an impact.” Walking after a meal, for example, may help you avoid blood glucose spikes.
6. Sunrise, Sunset
Taking a blood glucose reading first thing when you wake up, right before bed, and, if directed by your provider, about halfway through your normal sleeping hours on occasion can provide a wealth of information. “A bedtime blood sugar is important,” says O’Donnell. “You wouldn’t want someone going to bed with hypoglycemia.” Even if blood glucose is normal at bedtime, it may fall as you sleep, so setting your alarm for a mid-snooze check can provide peace of mind that you are staying in a healthy range. A test when you wake up reveals fasting glucose levels, which is helpful for doctors as they figure out what medications work best for you.
7. Tech Support
Whether you use a ratty old notebook or a sparkling smartphone to log your data is a matter of personal taste. Bedrich is a big supporter of pen and paper. “If you write things down, you get to look at it every time something happens,” she says. “That gives you lots of opportunities to see your data and analyze it.” On the other hand, just about everyone carries a smartphone these days. “That could help patients have it a little closer to them,” O’Donnell says, making it more convenient to log. Plus, blood glucose results stored in your meter and continuous glucose monitor can be uploaded to a computer and printed out, so you and your health care provider have tidy reports to consider. Be sure to review the reports yourself weekly.
8. Pattern Recognition
“One thing I try to stress is that if there’s one time that it’s important to log, if you feel things are out of control, it’s before a doctor’s appointment,” says O’Donnell. “It helps you and the provider figure out what’s going on.” Experts like to see multiple examples to help identify patterns. Ask your provider how many days to log to help provide meaningful information.
And keep in mind that your logbook isn’t just for your doctor—it’s for you. Checking your logbook daily for immediate feedback and weekly for patterns provides information that you can use. With that information, you can make changes that will get you to, or keep you in, your target blood glucose range. Some intense bouts of testing to get back on track may mean you will have less daily testing once you find a regimen that works.
The ADA Says
The American Diabetes Association (ADA) says there are certain times when people who take multiple daily insulin injections or use an insulin pump may need to check blood glucose: before and occasionally after meals and snacks, at bedtime, before exercise, if a low is suspected, after treating a low, and before critical tasks such as driving. For people who use insulin less frequently or who don’t use insulin, the ADA says that checking blood glucose can help guide decisions about medications, physical activity, eating plans, and other treatments.