What to Know About Blood Glucose Levels

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.

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.

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.

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.

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.

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.