A blood sugar, or blood glucose, chart identifies a person’s ideal blood sugar levels throughout the day, including before and after meals. It can help a person with glucose management if they need to keep levels within a normal range, such as those with diabetes.
Doctors use blood sugar charts to set target goals and monitor diabetes treatment plans. Blood sugar charts also help those with diabetes assess and self-monitor their blood sugar test results.
The ideal blood sugar level for an individual depends on when in the day they carry out blood glucose monitoring, as well as when they last ate.
In this article, we provide some charts that demonstrate the ideal blood sugar levels throughout the day. We also explain the importance of staying within the recommended ranges.
Blood sugar charts act as a reference guide for blood sugar test results. As such, blood sugar charts are important tools for diabetes management.
Most diabetes treatment plans involve keeping blood sugar levels as close to normal or target goals as possible. This requires frequent at-home and doctor-ordered testing, along with an understanding of how results compare with target levels.
Doctors often provide A1C blood sugar recommendations in blood sugar charts. They tend to give A1C results as both a percentage and an average blood sugar level in milligrams per deciliter (mg/dl).
|Time of check||Target blood sugar levels for people without diabetes||Target blood sugar levels for people with diabetes|
|Before meals||less than 100 mg/dl||80–130 mg/dl|
|1–2 hours after the start of a meal||less than 140 mg/dl||less than 180 mg/dl|
|Over a 3-month period, which an A1C test can measure||less than 5.7%||less than 7%|
less than 180 mg/dl
Although a doctor will provide these as a guide, they will also individualize a glucose management plan and include either more or less stringent personal targets.
An A1C test measures a person’s average blood sugar levels over a 3-month period, which gives a wider insight into their overall management of their blood sugar levels.
Appropriate blood sugar levels vary throughout the day and from person to person.
Blood sugars are often lowest before breakfast and in the lead up to meals. Blood sugars are often highest in the hours following meals.
People with diabetes will often have higher blood sugar targets or acceptable ranges than those without the condition.
These targets vary according to a range of factors, some of which include:
- age and life expectancy
- the presence of other health conditions
- how long a person has had diabetes
- diagnosed cardiovascular disease
- problems with the smallest arteries in the body
- any known damage to the eyes, kidneys, blood vessels, brain, or heart
- personal habits and lifestyle factors
- not being aware of low blood sugar levels
- other illnesses
Most blood sugar charts show recommended levels as a range, allowing for differences between individuals.
The American Diabetes Association, Joslin Diabetes Center, and American Association of Clinical Endocrinologists also offer slightly different blood sugar guidelines for those with diabetes.
Interpreting blood sugar meter readings depends mostly on individual patterns and targets. A medical professional will set these at the beginning of diabetes treatment.
Certain forms of temporary diabetes, such as gestational diabetes, also have separate blood sugar recommendations.
|Time of check||Blood sugar level|
|Fasting or before breakfast||60–90 mg/dl|
|Before meals||60–90 mg/dl|
|1 hour after meal||100–120 mg/dl|
A person with very high or low fasting blood sugar levels should take the following actions:
|Fasting blood sugar level||Risk level and suggested action|
|50 mg/dl or under||Dangerously low: Seek medical attention|
|70–90 mg/dl||Possibly too low: Consume sugar upon experiencing symptoms of low blood sugar, or seek medical attention|
|90–120 mg/dl||Normal range|
|120–160 mg/dl||Medium: Seek medical attention|
|160–240 mg/dl||Too high: Work to bring down blood sugar levels|
|240–300 mg/dl||Much too high: This could be a sign of ineffective glucose management, so see a doctor|
|300 mg/dl or above||Very high: Seek immediate medical attention|
As long as blood sugar levels do not become critically dangerous, there are ways to return them to within a normal range when readings become too high.
Some ways to lower blood sugar levels include:
- limiting carbohydrate intake but not fasting
- increasing water intake to maintain hydration and dilute excess blood sugar
- engaging in physical activity, such as a post-meal walk, to burn excess blood sugar
- eating more fiber
These methods should not replace medical treatment but are a helpful addition to any diabetes treatment plan. If blood sugar readings seem unusual or unexpected, consult a doctor.
That said, many factors relating to a monitoring device and its user can influence blood sugar readings, possibly causing them to be inaccurate.
Monitoring blood sugar levels is an important part of diabetes management. The best monitoring plans often rely on both self-monitoring at home and doctor-ordered tests, such as A1C tests.
Many types of blood sugar monitor are available for self-monitoring. Most blood sugar monitors in the United States involve using blood obtained from a finger prick and testing strips. These give blood sugar readings in mg/dl.
Modern home blood sugar meters produce plasma glucose counts instead of whole blood glucose counts.
This allows for more accurate readings of daily blood glucose levels. It is also easier to directly compare the results of self-monitoring and doctor-ordered tests, as doctors also use plasma glucose counts.
Tracking daily blood sugar level changes can help doctors understand how well treatment plans are working. This can help them determine when to adjust medications or targets. It can also help reflect the impact of diet and exercise.
The frequency of blood sugar tests varies among individual treatment plans, as well as the type and stage of diabetes.
Recommendations for testing are as follows:
Type 1, adult: Check at least twice daily, up to 10 times. People should perform their tests before breakfast, at fasting, before meals, sometimes 2 hours after meals, before and after physical activity, and at bedtime.
Type 1, child: Check at least four times daily. People should perform their tests before meals and at bedtime. Tests may also be required 1–2 hours after meals, before and after exercise, and overnight.
Type 2, people taking insulin or other management medications: The recommended frequency of testing varies depending on insulin dosage and the use of any additional medications.
Those taking intensive insulin should test when fasting, before meals and bedtime, and sometimes overnight. Those taking insulin and additional medications should at least perform tests at fasting and bedtime. People taking background insulin and one daily premixed insulin injection should perform tests when fasting, before premixed dosages and meals, and sometimes overnight.
Those not taking noninsulin oral medications or managing blood sugar levels through dietary adjustments require much less frequent blood sugar testing at home.
Type 2, when there is a low risk of low blood sugar: Often, daily tests are not necessary. Performing tests at meal times and bedtime should reflect the real-time impact of lifestyle changes.
If a person is not meeting blood sugar goals or A1C targets, the frequency of testing should increase until levels return to within the normal ranges.
Gestational: Those following a course of insulin should perform tests at fasting, before meals, and 1 hour after meals. Those not taking insulin should perform tests at fasting and 1 hour after meals.
People with gestational diabetes should test more regularly during periods of physical and emotional stress, such as acute illness or depression.
Continuous glucose monitors (CMGs) are devices that are particularly helpful for people who have difficulty using blood sugar meters. CMGs have a sensor that the individual inserts into their skin to measure the amount of sugar in tissue.
If blood sugar levels become much higher than or too far below the established targets, an alarm will sound. Some CMGs also track the changes in blood sugar level over the course of hours and display to the user whether levels are rising or falling.
A person should verify CMGs regularly by taking blood sugar levels with a finger-prick meter. It is best to perform tests at times when blood sugar levels are steady, so avoid testing straight after meals and bouts of physical activity.
Managing blood sugar levels is an important step in preventing the complications of diabetes.
Making sure that blood sugar levels stay within normal ranges can also be a strong sign that treatment is working.
Although many people will have individual requirements and characteristics that shape their target blood sugar range, a doctor will set these goals using a blood sugar chart at the start of treatment. They may adjust these targets as treatment progresses.
If a person notices any symptoms of either extremely low or extremely high blood sugar, they should seek medical attention.
What causes low blood sugar in people with diabetes?
Low blood sugar in a person with diabetes is most likely due to the medication they are taking.
Anyone experiencing periods of low blood sugar should discuss this with their doctor, as they may need to change the dosage or type of medication. Different types of insulin, for instance, have different peak times; some work right away, while others may take effect more slowly but last longer.
Diet and exercise also affect blood sugar levels, so coordinating the best times in relation to meals and medication may help. Keeping a journal that includes the food a person eats and when, the amount of medication they take and when, and any exercise they engage in will help them and their doctor devise a good plan.
Deborah Weatherspoon, PhD, RN, CRNA Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.