Your body supplies your cells with energy using blood glucose (blood sugar) produced from dietary carbohydrates. Normally, the body regulates blood glucose levels so there’s always enough to fuel cells, but not so much that the bloodstream is overloaded with sugar.
Intype 1 diabetes, the pancreas either does not produce enough insulin or does not produce insulin at all. Intype 2 diabetes, it produces too little insulin and/or the body isn’t able to use it properly. The same is true forgestational diabetes, a temporary form of the disease that develops during pregnancy.
Lack of insulin or insulin resistance causes higher than normal levels of glucose in the blood.
Blood sugar fluctuates throughout the day depending on what and when you eat, physical exertion, and other factors. This is whymonitoring glucose levelsis a key aspect of managing all types of diabetes, particularly for those who take insulin.Using aglucometerat home allows you to measure it regularly.
This article looks at blood glucose and what your ideal levels should be before and after a meal. It also discusseswhat your target glucose levels should be before exercise.
What Is Insulin?
Ideal Blood Glucose Levels
Your ideal level of blood glucose depends on a number of factors, including:
What’s more, various health organizations differ in what they consider to be ideal glucose levels.
If you have diabetes and blood glucose monitoring is a part of your treatment strategy, your healthcare provider will determine your target glucose levels. That said, there are some general guidelines worth knowing about.
Guidelines for Blood Glucose Monitoring
Preprandial (Pre-Meal)
Thelevel of sugar in your bloodstream before eatingis calledpreprandialblood glucose. It is very important to track your pre-meal blood glucose with an app or in a journal. This will help you and your healthcare provider identify trends in how yourblood sugar levels riseand fall over time. This is an indication of how well your diabetes treatment is working.
Fasting Blood Glucose
Everyone experiences a hormone surge each morning several hours before waking. This is known as thedawn phenomenon. Because people with diabetes don’t have a normal insulin response, this hormone surge results in higher-than-normal blood sugar levels.
The dawn phenomenon happens because there is this natural overnight release of hormones that increase insulin resistance. These include:
High morning blood sugarmay also have other causes, including:
This is different from dawn phenomenon.
Postprandial (Post-Meal)
Your blood sugar level within an hour or two after meals and snacks is called yourpostprandialblood glucose. As with preprandial blood glucose testing, it’s important to record your level each time you take it.
You also should write down everything you ate and how much of it you ate. This provides further information about how your body responds tocertain foods. This will help you and your healthcare provider fine-tune your diet and other aspects of your diabetes management plan.
Before and After Exercise
Regular physical activityis a key part of managing diabetes. This is especially true for people with type 2 diabetes since losing weight can make a big difference in overall health. For those with type 1 diabetes, exercise can help increase sensitivity to insulin and control blood sugar.
Because physical activity uses energy, it depletes glucose cells, drawing glucose from the bloodstream. This can potentially lead tohypoglycemia(low blood sugar).
This is why checking your blood sugar levels before activity and immediately afterward is important. Your blood sugar levels can tell if you have enough glucose to fuel your workoutandhow much you’ve depleted it while exercising.
Target glucose ranges vary from person to person, but your blood sugar levels should be at least 90 mg/dL before starting exercise. If you test your blood glucose and it’s lower than 90 mg/dL, here are the steps to take depending on your exact reading.
Target Pre-Exercise Blood Glucose LevelsPre-Exercise Blood Glucose (mg/dL)What to DoLess than 90Before exercising, eat 15 to 30 grams (g) of fast-acting carbs based on your size and intended activity.For prolonged activities at moderate intensity: Eat more carbs as needed (0.5–1.0 g/kg body mass per hour of exercise) based on your blood sugar testing results.Brief (less than 30 minutes) or high-intensity activities may not require additional carb intake.90 to 150Start eating carbs at the onset of most exercise (approximately 0.5–1.0 g/kg body mass per hour of exercise). The amount you should eat depends on the type of activity and the amount of active insulin.150 to 250Start exercising and don’t eat carbs until your blood glucose levels are less than 150 mg/dL.250 to 350Test for ketones and do not exercise if there are moderate-to-large amounts of ketones present.Start with mild-to-moderate intensity exercise. Avoid intense exercise until your glucose levels are less than 250 mg/dL, as intense exercise may exaggerate the high blood sugar.350 or higherTest for ketones and do not exercise if there are moderate-to-large amounts of ketones present.If ketones are negative (or trace), consider correcting with insulin before you exercise, depending on your active insulin status.Start with mild-to-moderate intensity exercise and refrain from intense exercise until your glucose levels decrease.After you work out, test your blood glucose right away. Test again two to four hours afterward to check for a delayed drop in your level. If your blood sugar is lower at this point, continue checking it every two to four hours or until it’s no longer low and you’re sure your glycogen has been restored to normal.A1C Test LevelsIt is important to regularly self-monitor your glucose levels. Even if your glycemic control is stable, however, it’s likely your healthcare provider will want you to come in for ahemoglobin A1C testor other assessment twice a year.This may change if you don’t have adequate control of your blood sugar levels or you’ve had a recent change in your medication. In these cases, your healthcare provider may want to do A1C or other testing at least four times a year.For most non-pregnant adults with diabetes, the American Diabetes Association recommends an A1C goal of less than 7%. An A1C goal of less than 8%, however, may be right for those with a limited life expectancy or when the harms of treatment outweigh the benefits.It’s important to work with your healthcare team to set your own individual A1C goal.SummaryYour target blood glucose levels may vary depending on your age, and other factors like what medications you take and how long you’ve had diabetes. Your healthcare provider will work with you to determine what blood glucose targets are right for you.It is important to monitor your blood glucose levels before and after meals and before exercise. This can give you important information about how your body responds to different foods and activities.A Word From VerywellTesting your blood glucosethroughout the daywill help you control it. Managing your diabetes means knowing how food, exercise, stress, illness, and other factors affect your levels.Your certified diabetes educator or healthcare provider will help you develop a daily testing routine that works with your schedule.You will probably need to test your blood sugar fairly often if you take insulin or anoral diabetes medicationthat can cause hypoglycemia, or if you have poor glucose control. But this is not a bad thing; it simply means you need to keep close tabs on any fluctuations in your glucose levels. That way, you can deal with them and then go on with your day.
After you work out, test your blood glucose right away. Test again two to four hours afterward to check for a delayed drop in your level. If your blood sugar is lower at this point, continue checking it every two to four hours or until it’s no longer low and you’re sure your glycogen has been restored to normal.
A1C Test Levels
It is important to regularly self-monitor your glucose levels. Even if your glycemic control is stable, however, it’s likely your healthcare provider will want you to come in for ahemoglobin A1C testor other assessment twice a year.
This may change if you don’t have adequate control of your blood sugar levels or you’ve had a recent change in your medication. In these cases, your healthcare provider may want to do A1C or other testing at least four times a year.
For most non-pregnant adults with diabetes, the American Diabetes Association recommends an A1C goal of less than 7%. An A1C goal of less than 8%, however, may be right for those with a limited life expectancy or when the harms of treatment outweigh the benefits.
It’s important to work with your healthcare team to set your own individual A1C goal.
Summary
Your target blood glucose levels may vary depending on your age, and other factors like what medications you take and how long you’ve had diabetes. Your healthcare provider will work with you to determine what blood glucose targets are right for you.
It is important to monitor your blood glucose levels before and after meals and before exercise. This can give you important information about how your body responds to different foods and activities.
A Word From Verywell
Testing your blood glucosethroughout the daywill help you control it. Managing your diabetes means knowing how food, exercise, stress, illness, and other factors affect your levels.
Your certified diabetes educator or healthcare provider will help you develop a daily testing routine that works with your schedule.
You will probably need to test your blood sugar fairly often if you take insulin or anoral diabetes medicationthat can cause hypoglycemia, or if you have poor glucose control. But this is not a bad thing; it simply means you need to keep close tabs on any fluctuations in your glucose levels. That way, you can deal with them and then go on with your day.
6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
National Institute of Diabetes and Digestive and Kidney Diseases.Diabetes diet, eating, & physical activity.American Diabetes Association.The big picture: checking your blood glucose.American Diabetes Association Professional Practice Committee.6. Glycemic targets: standards of medical care in diabetes—2022.Diabetes Care. 2022;45(Supplement_1):S83-S96. doi:10.2337/dc22-S006Porcellati F, Lucidi P, Bolli GB, Fanelli CG.Thirty years of research on the dawn phenomenon: lessons to optimize blood glucose control in diabetes.Diabetes Care. 2013;36(12):3860-2. doi:10.2337/dc13-2088American Diabetes Association Professional Practice Committee.5. Facilitating behavior change and well-being to improve health outcomes: Standards of medical care in diabetes—2022.Diabetes Care. 2022;45(Supplement_1):S60-S82. doi:10.2337/dc22-S005Colberg SR, Sigal RJ, Yardley JE, et al.Physical activity/exercise and diabetes: a position statement of the American Diabetes Association.Diabetes Care. 2016;39(11):2065-2079. doi:10.2337/dc16-1728
National Institute of Diabetes and Digestive and Kidney Diseases.Diabetes diet, eating, & physical activity.
American Diabetes Association.The big picture: checking your blood glucose.
American Diabetes Association Professional Practice Committee.6. Glycemic targets: standards of medical care in diabetes—2022.Diabetes Care. 2022;45(Supplement_1):S83-S96. doi:10.2337/dc22-S006
Porcellati F, Lucidi P, Bolli GB, Fanelli CG.Thirty years of research on the dawn phenomenon: lessons to optimize blood glucose control in diabetes.Diabetes Care. 2013;36(12):3860-2. doi:10.2337/dc13-2088
American Diabetes Association Professional Practice Committee.5. Facilitating behavior change and well-being to improve health outcomes: Standards of medical care in diabetes—2022.Diabetes Care. 2022;45(Supplement_1):S60-S82. doi:10.2337/dc22-S005
Colberg SR, Sigal RJ, Yardley JE, et al.Physical activity/exercise and diabetes: a position statement of the American Diabetes Association.Diabetes Care. 2016;39(11):2065-2079. doi:10.2337/dc16-1728
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Guidelines for Blood Glucose TestingBlood Glucose Levels: What’s Normal, What’s NotWhat Blood Glucose Meter Is Right for You?10 Steps for Using a GlucometerCheck Your Blood Sugar Anywhere With These 4 Best GlucometersContinuous Glucose Monitoring: Weighing the Pros and Cons
Guidelines for Blood Glucose Testing
Blood Glucose Levels: What’s Normal, What’s Not
What Blood Glucose Meter Is Right for You?
10 Steps for Using a Glucometer
Check Your Blood Sugar Anywhere With These 4 Best Glucometers
Continuous Glucose Monitoring: Weighing the Pros and Cons
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