Blood Sugar Levels: What is Normal, Low or High, & More (2023)

When people are newly diagnosed with diabetes, one of the first questions they ask is what their blood sugar levels should be; what is normal, too high, or too low? Since everyone’s personal health history and the way their body functions is as unique as a fingerprint, it may affect how the body responds to food, medication, and other factors that influence blood sugar levels.

Health organizations provide guidelines for normal glucose levels in people without diabetes, which are slightly different from the normal or target levels recommended for people diagnosed with diabetes. If you have diabetes, your healthcare provider will work with you to personalize your target blood sugar levels to meet your individual health needs.

This article is intended to help you get started with understanding the basic aspects of blood sugar levels, including:

  • What is blood sugar?
  • What are normal blood sugar levels?
  • Factors that can affect blood sugar levels
  • High blood sugar: hidden dangers
  • Low blood sugar: what to watch out for

What is blood sugar?

When you eat, the carbohydrate in your food is broken down into a usable form of energy called glucose. Glucose — also known as sugar — enters the bloodstream and a hormone called insulin helps move it into our cells.

This process lowers the amount of glucose in the bloodstream. When this process works efficiently, your muscles and organs have the fuel they need without there being too much glucose remaining in the blood.

What are normal blood sugar levels?

Health organizations like the American Diabetes Association (ADA) and Centers for Disease Control and Prevention (CDC) provide the following guidelines on normal blood sugar levels for people without diabetes:

Fasting plasma glucose

This blood sugar measurement is taken while you’re fasting – at least 8 hours from when you last ate – such as first thing in the morning.

  • ADA recommendation: Fasting plasma glucose level below 100 mg/dL.

After meal / 2 hour plasma glucose

This blood sugar measurement is taken 2 hours after the start of a meal, or 2 hours after ingesting a sugary liquid during an oral glucose tolerance test.

  • ADA recommendation: Blood glucose level below 140 mg/dL.


This blood test is taken independent of when you have eaten. It measures the amount of glucose that is stuck to the hemoglobin (part of your red blood cells), which accumulates over approximately 3 months.

  • CDC recommendation: Less than 5.7%.

Normal blood sugar levels chart

Fasting plasma glucose2 hours after a mealA1C
Below 100 mg/dLBelow 140 mg/dLLess than 5.7%

Target blood sugar levels for people with diabetes

People with diabetes have difficulty creating or using enough insulin, which is the hormone that helps convert glucose into energy. Although there is no universal blood sugar chart for everyone with diabetes, clinical organizations like the ADA and American Association of Clinical Endocrinologists (AACE) offer guidelines on target blood sugar levels as a starting point.

Healthcare providers typically tailor normal blood sugar target ranges to an individual diabetes care plan. This includes considering your:

  • Age
  • Lifestyle
  • Years since diabetes diagnosis
  • Other health conditions
  • Risk for severe low blood sugars
  • Mental state
  • Economic resources available to reach blood sugar goals

If you do not have target guidelines from your healthcare provider yet, you can use the blood sugar level charts below. This will help you get started with testing at home with a blood glucose meter and will make it easier to understand target A1C levels.

Target blood sugar ranges for non-pregnant people with diabetes

Before Meals70-130mg/dLLess than 110 mg/dL
2 Hours After a MealLess than 180 mg/dLLess than 140 mg/dL
A1C (HbA1c)Less than 7.0%Less than 6.5%

Target blood sugar ranges for pregnant people with diabetes

Blood sugar targets during pregnancy are lower due to hormonal influences. The ADA, AACE, and Joslin Diabetes Center have slightly different guidelines for target blood sugar levels during pregnancy. In general, pregnant women with diabetes will want to follow individual guidelines provided by their endocrinologist.

The ADA recommends maintaining blood sugar levels of 95-140 mg/dL for pregnant women. However, some providers recommend an even tighter goal of blood glucose levels below 89 mg/dL before a meal and below 120 mg/dL after a meal.

To keep close tabs on levels, most diabetes specialists recommend that women with diabetes during pregnancy check their blood sugar:

  • First thing in the morning (fasting)
  • Before all meals
  • 1 hour after all meals
  • At bedtime
  • Occasionally at 3 a.m.

Track your own personal ranges with our free weekly and monthly blood sugar charts >

Factors that can affect blood sugar levels

If you have prediabetes or diabetes, you may have insulin resistance or an inability to produce insulin. This means your body has difficulty regulating blood sugar levels on its own.

It’s a delicate balance to maintain, so the following list can help you familiarize yourself with factors that can cause your blood glucose levels to go up or down.

Why your blood sugar level may be high

Based on the ADA guidelines above, if your blood sugar is above 180 mg/dL two hours after a meal, it is considered above the normal range. What might cause your glucose or blood sugar to rise? Consider the following factors:

  • Consuming more carbohydrates or a larger meal than usual
  • Not taking enough insulin or oral diabetes medication based on carbohydrates or activity levels
  • Reduced physical activity
  • Illness, stress, and pain (both short-term and long-term)
  • Menstrual periods
  • Dehydration
  • Side effects from medications like steroids or antipsychotics

Why your blood sugar level may be low

If blood sugar drops below 70 mg/dL, it is below normal levels. This can be caused by a variety of factors, such as:

  • Not eating enough or missing a meal or snack
  • Reducing the amount of carbohydrates you normally eat
  • Alcohol consumption — especially if you’re drinking on an empty stomach
  • Taking too much insulin or oral diabetes medication based on carbohydrates or activity levels
  • Increased physical activity
  • Side effects from medications (other than steroids or antipsychotics)

If you have diabetes, keep your blood glucose meter and sources of fast-acting glucose (like glucose tabs or fruit juice) close by in case your blood sugar drops. This is especially important for people with hypoglycemia unawareness, which is a condition that causes symptoms of low blood sugar to go unnoticed.

Eating balanced meals and snacks at regular times throughout the day is a big part of maintaining normal blood glucose levels. Check out our article on meal planning for diabetes to better understand the three macronutrients where calories come from and which have the biggest effect on blood sugar.

Meal Planning for Diabetes: How to Optimize Your Diet [Free Meal Plan Chart] >

Everyone will respond differently to certain factors, which is why it’s important to have individualized target glucose levels. To help you reach your target blood glucose goals, work with your healthcare provider to discuss modifications to your diet, physical activity, or medications, and alert them of other factors like a recent illness or stressful event.

High blood sugar: hidden dangers

In the short term, high blood sugar levels can zap your energy, cause excessive thirst and urination, and blur your vision. High blood sugar levels can also lead to dehydration, dry and itchy skin, and infections. Minimizing the time spent above your target blood sugar range can help you feel your best and will help prevent complications and injury to your body.

Over time, high blood sugar affects many parts of the body. Chronic high blood sugar can start to cause noticeable changes, including:

  • Memory problems
  • Vision problems like blurriness, diabetic retinopathy, and blindness
  • Gum disease that leads to tooth loss, which can make eating healthy foods difficult due to problems chewing
  • Heart attack and stroke due to increased plaque build-up in the vessels and other vascular issues
  • Kidney disease, which can lead to the need for dialysis or a kidney transplant
  • Nerve damage that can cause decreased sensation in the feet and legs which increases the risk for wounds to turn into serious infections and even amputation

Nerve damage from high blood sugar can also cause a variety of symptoms including:

  • Pain and tingling in the feet and hands
  • Difficulty emptying your bladder
  • Problems during the digestion process after eating, which can cause food to sit in the stomach too long and lead to nausea, vomiting, and erratic blood sugar levels

People with diabetes are often reluctant to talk about it, but nerve damage from high blood sugar can also affect sexual response and function for men and women. Don’t be embarrassed to reach out to your doctor for help in any of these areas.

Checking your blood sugar frequently and taking immediate action when it is above range can reduce your risk of complications.

High blood sugar chart and action plan

High blood sugar is also referred to as hyperglycemia. This happens when the body does not have enough insulin or can’t use insulin properly due to insulin resistance.

The numbers below represent values in the hyperglycemic range and require action to bring levels down to a normal range.

Blood Sugar ReadingAlert Level and Treatment Plan
180-250 mg/dLYellow Flag: Blood sugar is above normal levels.

When blood sugar levels are high, it can indicate that the body does not have enough insulin or glucose lowering medication. Levels may be elevated due to a large meal, if you have an illness or infection, are stressed, or are inactive. If you are newly diagnosed, it may take a little time to get you below this range.

Your healthcare provider may provide individualized instructions on when to contact the office. If you have two or more unexpected blood sugars over 250 mg/dL, notify your healthcare provider for instructions.

Higher than 250 mg/dLRed Flag: Blood sugar is very high and requires immediate treatment.

More than two unexpected blood sugar readings over 250 mg/dL require medical attention. Testing for ketones is recommended for people with Type 1 diabetes and those with Type 2 diabetes on insulin therapy who are having vomiting and symptoms of severe illness.

When blood sugar levels are this high, it could be a sign of ineffective glucose management, a problem with your insulin or insulin pump infusion set, illness, or another problem. Notify your healthcare provider for further treatment instructions.

Do not exercise if your blood sugar is over 250 mg/dL and make sure to drink plenty of water.

Low blood sugar: what to watch out for

Hypoglycemia (low blood sugar) can occur in people with diabetes who:

  • Take too much medication or insulin
  • Are late eating a meal or snack
  • Have increased physical activity
  • Drink too much alcohol

Symptoms of low blood sugar include feeling weak, sweaty or clammy, confused, hungry and/or irritable. Sometimes people experience a fast heartbeat and some symptoms may make a person appear to be drunk. A severely low blood sugar can result in unconsciousness, seizures, coma or death — especially when a low occurs during the night.

Low blood sugar affects many parts of the body, but the most frustrating part can be that hypoglycemia can happen anytime and anywhere — even when you think you are closely following the plan for your diabetes care. If low blood sugar is severe, people may need to go to the hospital to help raise their glucose level or miss work due to the side effects.

It can happen during a date, during a business meeting, or even while driving, which is the most dangerous scenario if there is confusion or loss of consciousness while behind the wheel. It’s important to use your blood glucose meter to check your blood sugar before you drive to keep yourself and others safe. Frequent testing with your blood sugar meter and taking action when blood sugar is trending low can prevent a severe low and keep your life on track.

Low blood sugar chart and action plan

Low blood sugar is also called hypoglycemia. The numbers below represent values in the hypoglycemic range and require action to bring blood sugar levels up into a normal range.

Blood Sugar ReadingAlert Level and Treatment Plan
50 mg/dL or underRed Flag: Blood sugar is critically low and requires immediate treatment.

If a person is unable to speak and/or is not alert, treat with glucagon via injection or nasal spray. Call emergency medical response if necessary. Do not place food or drink into the mouth.

If a person is alert and able to speak clearly, treat with 15 grams of rapid-acting carbohydrate such as glucose gel, 4 oz regular soda, or fruit juice. Re-test blood sugar in 15 minutes and repeat as needed to bring blood sugar within range.

51-70 mg/dLRed Flag: Blood sugar is below normal levels and requires immediate treatment.

Treat with 15 grams of rapid-acting carbohydrate and re-test in 15 minutes. Repeat treatment as needed to bring blood sugar within range.

71-90 mg/dLYellow Flag: Blood sugar levels should be watched and treated as needed.

If you’re having symptoms of low blood sugar, treat with 15 grams of rapid-acting carbohydrate and re-test in 15 minutes.

Repeat treatment or follow with a meal. If it is meal time, move forward with eating the meal. People often fall into this range when they are late for a meal or have been especially active.

Anytime your symptoms don’t match the number on your blood sugar meter, repeat the test. Don’t count on your body to tell you if your blood sugar is high or low — many of the symptoms of highs and lows are similar.

Discussing your unique health goals and challenges with your healthcare provider can provide customized target ranges for normal blood sugar levels and action plans based on your needs. Maintaining healthy blood sugar levels is important to your overall health, so remember to check your blood sugar frequently. Taking immediate action when blood sugar is above range can help reduce your risk of health complications, and if low, keep you safe.

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