What to Know About Blood Glucose Levels

An Overview of Ideal Target Levels

Blood glucose (blood sugar) is produced from dietary carbohydrates to supply the body's cells with energy. 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, which could cause significant tissue damage.

For people with diabetes, this delicate balance is thrown off due to problems with insulin, a hormone produced by the pancreas that helps keep blood glucose levels steady and stable.

In type 1 diabetes, the pancreas either does not produce enough insulin or does not produce insulin at all. In type 2 diabetes, it produces too little insulin and/or the body isn't able to use it properly. The same is true for gestational diabetes, a temporary form of the disease the develops during pregnancy.

Lack of insulin or insulin resistance causes higher than normal levels of glucose in the blood.

Because blood sugar fluctuates throughout the day depending on when food was last eaten, what was eaten, physical exertion, and other factors, monitoring glucose levels is a key aspect of managing all types of diabetes—particularly for those who take insulin.

Ideal Blood Glucose Levels

The specific level of blood glucose that's considered ideal for you depends on your age, how long you have had diabetes, medications you take, and any other medical conditions you may have, among other factors.

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 have the last word on what your target glucose levels at any given time during the day should be.

That said, there are some general parameters worth knowing about, according to the American Diabetes Association.

Preprandial (Pre-Meal)

Preprandial blood glucose refers to the level of sugar in the bloodstream before eating.

Determining your pre-meal blood glucose and—this is key—recording it in a journal or with an app will allow you and your healthcare provider to identify trends in how your blood sugar levels rise and fall over time. This is an indication of how well your diabetes treatment is working.

Target Preprandial Blood Glucose Levels
Person Target
Adults (who are not pregnant) 80 to 130 mg/dL
Pregnant women with gestational diabetes Less than 95 mg/dL
Pregnant women with pre-existing type 1 or type 2 diabetes 70 mg/dL to 95 mg/dL

Fasting Blood Glucose

Everyone experiences a hormone surge called the dawn phenomenon each morning several hours before they wake up. For people with diabetes, this hormone surge results in higher-than-normal blood sugar levels because they don't have a normal insulin response to adjust for it.

The dawn phenomenon happens because, during the night, the body produces less insulin as the liver produces more glucose. The lack of insulin results in a blood sugar rise in the morning.

Postprandial (Post-Meal)

Postprandial blood glucose refers to blood sugar levels within an hour or two after meals and snacks.

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. This provides further information about how your body responds to certain foods, which in turn will help you and your healthcare provider fine-tune your diet and other aspects of your diabetes management plan.

Target Postprandial Blood Glucose Levels
Person Target
Adults (who are not pregnant) Less than 180 mg/dL
Women with gestational diabetes, 1 hour after eating Less than 140 mg/dL
Women with gestational diabetes, 2 hours after eating Less than 120 mg/dL
Pregnant women with pre-existing type 1 or type 2 diabetes, 1 hour after eating 110-140 mg/dL
Pregnant women with pre-existing type 1 or type 2 diabetes, 2 hours after eating 100-120 mg/dL

Before and After Exercise

Regular physical activity is a key part of managing diabetes. This is especially true for people with type 2 diabetes, as losing weight could make an enormous difference in overall health. For those with type 1 diabetes, exercise can help increase sensitivity to insulin and control blood sugar.

However, because physical activity uses energy, it depletes cells of glucose, drawing glucose from the bloodstream and potentially leading to hypoglycemia (low blood sugar).

Checking your blood sugar levels before being active and immediately afterward can tell you if you have enough glucose to fuel your workout and the degree to which you've depleted it while exercising.

Target glucose ranges vary from person to person, but in general, it is ideal for blood sugar levels to be between 126 mg/dL and 180 mg/dL before starting exercise.

If you test your blood glucose and it's lower than 126 mg/dL, here are the steps to take depending on the exact reading you get.

Target Pre-Exercise Blood Glucose Levels
Pre-Exercise Blood Glucose What to Do
90 mg/dL or less Eat 10 to 20 grams (g) of carbs and wait until glucose levels exceed 90 mg/dL. An apple with peanut butter should do it.
90 mg/dL to 124 mg/dL Eat 10 g of carbs (a protein bar with 10 g of carbohydrate, for example) and then start high-intensity aerobic or anaerobic exercise.
126 mg/dL to 180 mg/dL It's fine to do either aerobic or anaerobic exercise, but monitor glucose during your workout.
182 mg/dL to 270 mg/dL Go ahead with your aerobic or anaerobic workout; if you're doing the latter, monitor your blood glucose.
Over 270 mg/dL Check your blood ketones with a urine test. If only slightly elevated (up to 1.4 mmol/L) it's fine to do a short, light workout. Do not exercise if your blood ketones are 1.5 mmol/L; instead, check in with your healthcare provider about how to manage your elevated glucose.

After you work out, test your blood glucose right away and 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

Besides regular self-monitoring of glucose levels, if your glycemic control is stable, it’s likely your healthcare provider will want you to come in for a hemoglobin A1C test or other assessment twice a year.

If you don’t have adequate control of your blood sugar levels or you’ve had a recent change in your medication, 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%. However, an A1C goal of less than 8% may be appropriate 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.

A Word From Verywell

Testing your blood glucose throughout the day will help you control it by revealing 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.

If you take insulin or an oral diabetes medication that can cause hypoglycemia, or if you have poor glucose control, you probably will need to test your blood sugar fairly often. But this is not a bad thing: It simply means you need to keep close tabs on any fluctuations in your glucose levels so that you deal with them and then go on with your day.

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6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. American Diabetes Association. The big picture: Checking your blood glucose.

  3. American Diabetes Association Professional Practice Committee. 6. Glycemic targets: Standards of medical care in diabetes—2022Diabetes Care. 2022;45(Supplement_1):S83-S96. doi:10.2337/dc22-S006

  4. 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

  5. American Diabetes Association Professional Practice Committee. 5. Facilitating behavior change and well-being to improve health outcomes: Standards of medical care in diabetes—2022Diabetes Care. 2022;45(Supplement_1):S60-S82. doi:10.2337/dc22-S005

  6. 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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