What to Know About Blood Glucose Levels

An Overview of Ideal Target Levels

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Updated on March 13, 2022

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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.

How Insulin Works and Why You Need It

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
Non-pregnant adults	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 there is this natural overnight release of the so-called counter-regulatory hormones—including growth hormone, cortisol, glucagon, and epinephrine—which increases insulin resistance.

High morning blood sugar may also be caused by insufficient insulin the night before, insufficient anti-diabetic medication dosages, or carbohydrate snack consumption at bedtime, which is different from dawn phenomenon.

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
Less than 90 mg/dL	Eat 15 to 30 grams (g) of fast-acting carbs before exercising—depending on your individual size and intended activity. For prolonged activities at a moderate intensity, eat additional carbs as needed (0.5–1.0 g/kg body mass per hour of exercise) based on your blood sugar testing results. Some activities that are brief (less than 30 minutes) or at a high intensity may not require additional carb intake.
90 mg/dL to 150 mg/dL	Start eating carbs at the onset of most exercise (approximately 0.5–1.0 g/kg body mass per hour of exercise), depending on the type of activity and the amount of active insulin.
150 mg/dL to 250 mg/dL	Start exercising and hold off on consuming carbs until your blood glucose levels are less than 150 mg/dL.
250 mg/dL to 350 mg/dL	Test for ketones and refrain from exercise if there are moderate-to-large amounts of ketones present. Start mild-to-moderate intensity exercise, avoiding intense exercise until glucose levels are less than 250 mg/dL—as intense exercise may exaggerate the high blood sugar.
350 mg/dL or higher	Test for ketones and refrain from 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 active insulin status. Start 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 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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