Blood Sugar Spikes: Symptoms, Causes, Prevention

Blood sugar spikes can happen in people with type 1 diabetes and type 2 diabetes and make it difficult to have good blood sugar control. 

The main reason for blood sugar spikes is diet, but there are other factors to consider as well.

Keep reading to learn the symptoms of a blood sugar spike, and how to prevent blood sugar spikes from occurring.

What is a blood sugar spike?

A blood sugar spike is when your blood glucose (blood sugar) levels increase quickly. Another word for high blood sugar is hyperglycemia, and it can cause long-term health problems if it happens frequently.

If blood sugar spikes happen frequently and over a long time, they can cause health complications. Chronic high blood sugar can cause your arteries to harden, which reduces blood flow to important organs like your heart. 

Blood sugar spikes are most common after eating, but they can occur at other times during the day as well. Insulin is a hormone that helps lower your blood sugar levels and prevent blood sugar spikes. Blood sugar spikes and hyperglycemia occur when your body doesn’t produce enough insulin or if you have insulin resistance

Some of the potential complications from consistent hyperglycemia include heart disease, heart attack, stroke, kidney disease, vision loss, nerve damage, and more. These complications can occur with both type 1 diabetes and type 2 diabetes.

Your blood sugar goals might be different from other patients with diabetes. Your healthcare provider can help you identify your ideal blood sugar range based on other health conditions, your age, and your risk for low blood sugar.

In general, if your blood sugar levels increase quickly and are higher than 180 mg/dL, it can be considered a blood sugar spike. You might also consider a rapid change in blood sugar as a blood sugar spike, even if it doesn’t go as high as 180 mg/dL or higher.

Blood sugar goals

The goal for blood sugar levels after eating (when most blood sugar spikes occur due to eating) are as follows:

  • Less than 180 mg/dL one to two hours after starting a meal (American Diabetes Association)
  • Less than 140 mg/dL two hours after a meal (American Association of Clinical Endocrinologists)
  • For women with gestational diabetes: Less than 140 mg/dL one hour after a meal and less than 120 mg/dL two hours after a meal

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Symptoms of a blood sugar spike

Most of the time, you might not feel a blood sugar spike or hyperglycemia. If your blood sugar is very high (around 250-300 mg/dL), you can start developing hyperglycemia symptoms. If you have type 1 diabetes, a blood sugar spike can cause diabetic ketoacidosis (DKA), a serious condition that needs to be treated right away.

Some potential blood sugar spike symptoms include:

Symptoms of diabetic ketoacidosis (very high blood sugar in patients with type 1 diabetes) include:

  • Increased thirst
  • Increased urination
  • Fast, deep breathing
  • Dry skin and mouth
  • Flushed face
  • Fruity-smelling breath
  • Headache
  • Muscle stiffness or aches
  • Fatigue
  • Nausea and vomiting
  • Stomach pain
  • Positive urine ketone test

What causes blood sugar to spike?


The most common cause of a blood sugar spike is eating or drinking too many carbohydrates at once. Foods with carbohydrates turn into sugar when they’re digested and include fruits, vegetables (especially starchy vegetables like potatoes), grains, legumes, and some dairy products like milk and yogurt.

Foods and drinks high in added sugar are especially problematic for causing blood sugar spikes. Sugary drinks and desserts tend to cause more intense blood sugar spikes than foods with natural sugar like fruit because the sugar is much more concentrated.

If you eat a lot of carbohydrates and/or sugar at one time when you have diabetes, your body has a hard time making enough insulin to help lower your blood sugar. 

Even if your body still makes its own insulin with type 2 diabetes, your body typically doesn’t use insulin effectively, which is called insulin resistance. That’s why most blood sugar spikes occur after eating.


If you eat a high-fat meal containing carbohydrates, you may experience a delayed blood sugar spike. Fat takes longer to empty from your stomach, which means the carbohydrate-containing foods you ate along with the fatty foods might not be digested right away, leading to a delayed blood sugar spike.

Other reasons

Other reasons you might experience a blood sugar spike and general hyperglycemia include stress, illness or infection, or a missed dose of diabetes medication. 

If you have a blood sugar spike, it can sometimes signify that you have an infection. You should seek medical advice for signs of an infection right away since diabetes increases your risk of more severe illness and infections. 

The signs of infection to watch out for include:

  • Fever over 101 degrees Fahrenheit
  • Sweating or chills
  • Skin rash
  • Pain, tenderness, redness, or swelling
  • Wound or cut that won’t heal
  • Sore or scratchy throat
  • Sinus pain or drainage
  • Dry or moist cough that lasts more than two days
  • White patches in your mouth or on your tongue
  • Nausea, vomiting, or diarrhea
  • Flu-like symptoms (chills, aches, headache, or fatigue)
  • Vaginal itching
  • Painful or frequent urination or increased urge to urinate
  • Bloody, cloudy, or foul-smelling pee

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How long does a blood sugar spike last?

The length of time blood sugar spikes last varies greatly from person to person. Blood sugar spikes can last for a few minutes or may last hours. The length of your blood sugar spike depends on factors such as whether you have type 1 diabetes or type 2 diabetes, if you take any medication for your diabetes, and how long you’ve had diabetes.

If your body still produces enough insulin, your pancreas will help to correct your blood sugar spike by releasing insulin. However, if you’re very insulin resistant or insulin-deficient (as in the case of patients with type 1 diabetes), your blood sugar spike may last longer.

If you have a blood sugar spike that doesn’t go away after several hours, or your blood sugar remains above 300 mg/dL, you should contact your healthcare provider for medical advice.

How do you fix a blood sugar spike?

Blood sugar spikes can be more easily corrected if you take insulin, but they can be corrected without insulin as well. (If your blood sugar is very high and you’re on insulin, your healthcare provider may recommend taking a bolus dose of insulin to help correct the blood sugar spike.)

Hyperglycemia and blood sugar spikes can’t always be quickly fixed. Therefore, the more important thing is being able to prevent them from happening.

You can help promote healthy blood sugar levels (and help bring down a blood sugar spike) by getting some physical activity. Physical activity helps improve insulin sensitivity and can lower your blood glucose levels.

If you’re experiencing a blood sugar spike, be sure to avoid drinking sugary drinks or eating high-sugar and high-carbohydrate foods. 

Some examples of foods that are very low or free of carbohydrates include:

  • Meat (including chicken and fish)
  • Eggs
  • Cheese
  • Nuts
  • Seeds
  • Non-starchy vegetables (carrots, broccoli, cauliflower, bell peppers, etc.)

If your body produces too much insulin in response to your blood sugar spike, you may develop rebound hypoglycemia (low blood sugar). This is known as a blood sugar crash after the spike. Getting on this roller coaster pattern with high and low blood sugar levels can be hard to break and isn’t good for your body.

Watch out for signs of rebound hypoglycemia after a blood sugar spike. 

Some signs of hypoglycemia include:

  • An irregular or fast heartbeat
  • Fatigue
  • Pale skin
  • Shakiness
  • Anxiety
  • Sweating
  • Hunger
  • Irritability
  • Tingling or numbness of the lips, tongue, or cheek

If you do develop hypoglycemia symptoms after a blood sugar spike, be careful not to over-correct the low blood sugar, which can cause another blood sugar spike.

How to prevent blood sugar spikes

Prevention is the best way to avoid blood sugar spikes. Here are the five simple ways to prevent blood sugar spikes:

1. Avoid sugary drinks and added sugar in general

Sweet drinks like soda, sweetened tea and coffee, and fruit-flavored drinks are packed with added sugar. To make matters worse, liquids empty from your stomach very quickly, which means the sugar from the drinks is available in your bloodstream much quicker than eating solid food with carbohydrates or sugar.

Sugary drinks are one of the leading culprits behind blood sugar spikes. One 12-ounce can of standard cola provides 33 grams of added sugar, which is beyond the daily recommendation of fewer than 25 grams of added sugar per day for women and close to the limit of fewer than 36 grams of added sugar per day for men.

Sugary drinks aren’t the only sources of added sugar. It’s estimated that 60% of packaged foods contain some form of added sugar. 

Processed foods don’t always appear unhealthy – yogurt, cereal, bread, and other foods can contain hidden added sugar, so be sure to read the nutrition facts and ingredients labels.

how to cut out sugar

2. Be physically active

Being physically active helps lower your blood sugar levels. Exercise improves insulin sensitivity in patients with insulin resistance, which is the primary cause of type 2 diabetes and can cause blood sugar spikes.

Aim to get 30 minutes of physical activity each day. You can break it up into smaller segments to accommodate your busy lifestyle, such as three 10-minute bouts instead of straight 30 minutes.

Getting a mix of cardiovascular activity, as well as strength or resistance training, is ideal. Cardio exercise burns up stored sugar in your liver, which is replenished by pulling excess glucose from your bloodstream.

Maintaining healthy muscle mass can also promote healthy blood sugar levels and may help reduce blood sugar spikes.


3. Try to maintain a healthy weight

If you’re considered overweight, losing weight might help stabilize your blood sugar levels and prevent blood sugar spikes.

Losing 5-10% of your initial body weight can help prevent diabetes for at-risk people and can improve blood glucose control if you already have diabetes. For a 200-pound person, that would equal a 10-20 pound weight loss.

Weight loss improves insulin sensitivity and can help your body better control your blood sugar levels. 

The most important thing about weight loss is to do it sustainably. If you start following a restrictive diet or make other lifestyle changes that are difficult to maintain, you likely won’t benefit from the weight loss long-term.

4. Manage your stress level

When you’re stressed, your body’s adrenal glands release cortisol. Cortisol triggers the fight-or-flight response, which results in physical changes such as your pupils dilating and heart rate increasing. Cortisol also promotes hyperglycemia and reduces insulin levels. 

The problem with chronic stress is that cortisol levels remain increased for much longer than is healthy. Prolonged stress can cause health problems, including the risk of having blood sugar spikes. Some studies have found that cortisol is associated with increased blood sugar levels in people with type 2 diabetes. 

Some examples of stress-relieving activities include talk therapy, exercise, doing a hobby you enjoy, taking a vacation, or anything that helps reduce your stress.

stress and anxiety

5. Watch your portions of carbohydrates

Carbohydrates are a type of nutrient your body uses for energy. Carbohydrates are found in foods like grains, fruit, legumes, vegetables, and some dairy products like milk and yogurt.

Many vegetables are very low in carbohydrates, but a few vegetables are considered starchy. Starchy vegetables contain starch, a type of carbohydrate that raises your blood sugar. Examples of starchy vegetables include potatoes, winter squash, corn, and peas.

To practice portion control of carbohydrates and promote healthy blood sugar levels, try keeping your carbohydrate portions to a quarter of your plate, similar to the Plate Method for Diabetes


Your diet most often causes blood sugar spikes, but they can also happen if you’re sick or have an infection, have high stress levels, or miss a dose of your diabetes medication.

Blood sugar spike symptoms are the same as the general symptoms of high blood sugar. But you might not always feel blood sugar spike symptoms. Checking your blood sugar is the best way to determine if you’re experiencing hyperglycemia or a blood sugar spike.

The best way to deal with blood sugar spikes is to prevent them through a healthy diet, getting regular physical activity, and managing your stress levels.

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  1. Adam TC, Hasson RE, Ventura EE, et al. Cortisol is negatively associated with insulin sensitivity in overweight Latino youth. J Clin Endocrinol Metab. 2010. 

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