Diabetes
Glucose Monitoring
Blood Glucose Monitoring Guide
- Monitoring Guidelines
- Target Levels
- Types of Monitors
- Using a Glucometer
- Best Glucometers
- Using CGM
An Overview of Ideal Target Levels
ByDebra Manzella, RN
Updated on October 10, 2024
Medically reviewed byIsabel Casimiro, MD, PhD
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.
For people with diabetes, this balance is thrown off due to problems with insulin. Insulin is a hormone produced by the pancreas that helps keep blood glucose levels 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 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 why monitoring glucose levels is a key aspect of managing all types of diabetes, particularly for those who take insulin. Using a glucometer at 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 discusses what 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:
- Your age
- How long you have had diabetes
- Medications you take
- Other medical conditions you may have
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)
The level of sugar in your bloodstream before eating is called preprandial blood 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 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 (mg/dL) |
| Non-pregnant adults without diabetes | 60 to 100 |
| Non-pregnant adults with diabetes | 80 to 130 |
| Pregnant people with gestational diabetes | Less than 95 |
| Pregnant people with pre-existing type 1 or type 2 diabetes | 70 to 95 |
Fasting Blood Glucose
Everyone experiences a hormone surge each morning several hours before waking. This is known as the dawn 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:
- Growth hormone
- Cortisol
- Glucagon
- Epinephrine
High morning blood sugar may also have other causes, including:
- Insufficient insulin the night before
- Insufficient anti-diabetic medication dosages
- Carbohydrate snack consumption at bedtime
This is different from dawn phenomenon.
Postprandial (Post-Meal)
Your blood sugar level within an hour or two after meals and snacks is called your postprandial blood 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 to certain foods. This 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 (mg/dL) |
| Adults (who are not pregnant) | Less than 180 |
| Women with gestational diabetes, 1 hour after eating | Less than 140 |
| Women with gestational diabetes, 2 hours after eating | Less than 120 |
| Pregnant women with pre-existing type 1 or type 2 diabetes, 1 hour after eating | 110-140 |
| Pregnant women with pre-existing type 1 or type 2 diabetes, 2 hours after eating | 100-120 |
Before and After Exercise
Regular physical activity is 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 to hypoglycemia (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 workout and how 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 Levels | |
|---|---|
| Pre-Exercise Blood Glucose (mg/dL) | What to Do |
| Less than 90 | Before 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 150 | Start 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 250 | Start exercising and don't eat carbs until your blood glucose levels are less than 150 mg/dL. |
| 250 to 350 | Test 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 higher | Test 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 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 a hemoglobin A1C test or 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 glucose throughout the day will 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 an oral diabetes medication that 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 our editorial process to 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-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
Additional Reading
Garber AJ, Handelsman Y, Grunberger G, et al. Consensus statement by the American Association of Clinical Endocrinologists and American College of Endocrinology on the comprehensive type 2 diabetes management algorithm - 2020 executive summary. Endocr Pract. 2020;26(1):107-139.doi:10.4158/CS-2019-0472
By Debra Manzella, RN
Debra Manzella, MS, RN, is a corporate clinical educator at Catholic Health System in New York with extensive experience in diabetes care.
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