Best Times of Day to Check Your Blood Sugar
These guidelines are intended to help those recently diagnosed with diabetes learn the basics of blood sugar monitoring.
Your blood sugar can change constantly throughout the day—which is what makes living with type 1 diabetes the most challenging. There are over 40 different factors (like food, activity, stress, caffeine) that can affect your blood sugars. If you’re just getting started in your diabetes education, this can be truly overwhelming.
Checking your blood sugar with test-strips or a flash blood glucose monitor (FBGM) several times throughout the day is just as important as taking your insulin and medications.
For example, checking your blood sugar before breakfast tells you how accurate your insulin doses are for managing the eight hours you were asleep, but it doesn’t tell you how accurate your insulin doses are for your meals.
Here, we’ll look at the best times to check your blood sugar for the most information about your diabetes management.
Fasting blood sugar (as soon as you wake up, before breakfast)
Your fasting blood sugar level is the best starting place, because you weren’t eating for the eight hours you were asleep.
A high fasting blood sugar level in the morning could suggest:
- Your body may need more rapid-acting insulin for the meal you ate last night, before bed. Consider setting an alarm to check your blood sugar in the middle of the night to determine if your blood sugar is actually high throughout the night or only closer to morning.
- Your body may need more basal/background during the overnight hours.
- You’re experience “dawn phenomenon” and need to work with your healthcare team to determine dosing insulin to manage consistent morning spikes.
A low fasting blood sugar level in the morning could suggest:
- Your body may need less rapid-acting insulin for the meal you ate last night, but if this were the case, you likely would be low for several hours before waking up in the morning. Consider setting an alarm to check your blood sugar in the middle of the night to determine if you’re experiencing low blood sugars throughout the night or only closer to morning.
- Your body may be getting more basal/background than it needs during those overnight hours.
Talk to your healthcare team about making any adjustments to your diabetes regimen to help you achieve your blood sugar goals.
Before, during and after exercise
Checking your blood sugar around exercise is especially important for people who take insulin or other diabetes medications that can cause low blood sugar. Remember to always carry fast-acting carbohydrates with you while exercising.
Especially if you’re new to exercise (and new to diabetes), it’s extremely important to check your blood sugar before, during and after exercise to identify and prevent low blood sugars. The more you study the way different types of exercise impact your blood sugar, the more you can develop a consistent plan around meals and exercise to prevent highs and lows.
A low blood sugar level before, during, or after exercising could suggest:
- Your body may need less rapid-acting insulin for the meal or snack you eat before exercising.
- Your body may need a temp-basal if you use an insulin pump, programmed to start at least 60 minutes before you start exercising.
- You might consider exercising before you eat to reduce the amount of insulin you have active in your system.
A high blood sugar level during, or after exercising can happen, too. Certain types of exercise—like weightlifting, spinning, sprinting—can trigger your liver to release stored sugar for extra fuel and the conversion of lactic acid into blood glucose. Many people take a small bolus of insulin before or during these “anaerobic” types of exercise to prevent high blood sugars.
Talk to your healthcare team about making any adjustments to your diabetes regimen to help you achieve your blood sugar goals.
Right before lunch or dinner
If you’re having trouble getting into your goal range right before your next meal, it’s very possible that your body isn’t getting enough insulin overall. This can take a bit of fine-tuning with your healthcare team’s support.
Keep in mind that some meals take longer to digest than others. High-fat meals that are also high in carbohydrates (like pizza, Chinese food, cake with buttercream frosting, tacos, etc.) can take many hours to digest, affecting your blood sugar for many hours, too. This means that even though it’s been four hours since your last meal, a high-fat meal could be still impacting your blood sugars four hours later because it’s digesting so slowly.
A high blood sugar level before lunch or dinner could suggest:
- What you ate or drank at your last meal is still being digested and you didn’t get enough insulin with that meal.
- Your body may need more rapid-acting insulin for your last meal.
- Your body may need more basal/background insulin during that time of day.
- Your body may need some extra help from a non-insulin diabetes medication.
A low blood sugar level before your next meal could suggest:
- Your body may need less basal/background insulin during that time of day.
- If you also engaged in physical activity after your last meal, you may need a reduced meal dose.
Talk to your healthcare team about making any adjustments to your diabetes regimen to help you achieve your blood sugar goals.
Two hours after eating a meal
Checking your blood sugar approximately one to two hours after eating is hugely important, because it tells you if your body has the tools it needs in order to handle your meals. Being consistently higher or lower than your goal range after eating can tell you some very important and clear things about your current diabetes management regimen.
A high blood sugar level one to two hours after eating could suggest:
- Your body may need more rapid-acting insulin for your last meal.
- If you were high before the meal, and high two hours after, your body may need more basal/background insulin.
A low blood sugar level in the hours after eating could suggest:
- Your body may need less rapid-acting insulin for your last meal.
- If you also engaged in physical activity after eating, you may need a reduced meal dose.
Talk to your healthcare team about making any adjustments to your diabetes regimen to help you achieve your blood sugar goals.
Right before bed
You’re about to spend eight hours sleeping! Those eight hours make up ⅓ of your day’s blood sugar levels, which means they have a big impact on your overall diabetes health, your next A1c, and your ability to be in your goal range the next morning.
A high blood sugar level right before bed or could suggest:
- Your body may need more rapid-acting insulin for your last meal.
- Your body may need more basal/background insulin during that time of day—especially if you’ve been struggling all day long with high blood sugars.
A low blood sugar level before bed or while you are sleeping:
- Your body may need less rapid-acting insulin with the meal you just ate.
- Your body may need less basal/background insulin during that time of day.
Talk to your healthcare team about making any adjustments to your diabetes regimen to help you achieve your blood sugar goals.
This content was made possible by Roche Diabetes Care, the makers of Accu-Chek, an active partner of Beyond Type 1 at the time of publication. Roche Diabetes Care was a Founding Partner of Beyond Type 1.
