How to Avoid Blood Sugar Highs and Lows
Type 2 DiabetesHow to Manage Type 2 Diabetes

How to Avoid Blood Sugar Highs and Lows if You Have Type 2 Diabetes

How to Avoid Blood Sugar Highs and Lows if You Have Type 2 Diabetes
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Updated on April 25, 2025
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Blood sugar control is a main goal for people living with type 2 diabetes. High blood sugar levels can lead to a variety of complications over time, including heart disease, nerve damage, and vision problems. Low levels can cause more immediate problems, such as confusion, dizziness, seizures, and potentially a loss of consciousness.

Everyone’s blood sugar goals differ by factors such as age and overall health, but the American Diabetes Association (ADA) recommends these target levels:

  • Before a meal: 80 to 130 milligrams/deciliter (mg/dL)
  • One to two hours after the start of a meal: less than 180 mg/dL

Keeping blood sugar levels as close to your target as possible is key to preventing complications and living well with type 2 diabetes.

Blood Sugar Highs and Lows

Glucose, or blood sugar, comes from two places: the food you eat and your liver. “Blood sugar is basically used to supply energy to the body,” explains Deborah Jane Wexler, MD, chief of the diabetes unit at Massachusetts General Hospital in Boston. For instance, one of your most valued organs, your brain, runs entirely on glucose, she says.

Insulin moves glucose into cells to be used for energy. When you have type 2 diabetes, your body doesn’t produce enough insulin or can’t effectively use the insulin it does produce. Without insulin, glucose builds up in the blood, leading to high blood sugar levels. Blood sugar may also rise if you eat a meal high in carbs, don’t take enough insulin or other diabetes medication, or have emotional or physical stress.

Low blood sugar can occur when you take too much insulin or other diabetes medication, skip a meal, eat fewer carbohydrates than usual, or increase your physical activity.

Monitoring blood sugar — by making sure it doesn’t spike too high or dip too low — is an important part of managing type 2 diabetes.

You can start by learning the signs of low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia) and what steps to take to bring those levels back to normal.

Hypoglycemia: If blood sugar is too low (usually below 70 mg/dL) you may have symptoms such as confusion, dizziness, nausea, nervousness, sweating, and tremors. You could even pass out, according to the ADA.

What to do: Follow the 15-15 rule. Have 15 grams of fast-acting carbohydrates — such as three or four glucose tablets, 4 ounces of fruit juice or regular soda, or a tablespoon of sugar — to raise your blood sugar, wait 15 minutes, and then check your blood sugar. If you’re still not in the target range, have 15 more grams of carbs. Repeat these steps until your blood sugar is back up to normal.

Hyperglycemia: Signs of high blood sugar include excessive thirst and urination, blurry vision, and fatigue. High blood sugar can be a problem for two reasons. Over the long term, high blood sugar quietly damages the small vessels of the eyes, kidneys, and nerves, leading to serious complications, such as blindness, kidney damage, and nerve damage. In the short term, it can cause excessive urination and weight loss. It may also pose a threat of coma or death. If your blood sugar is over 240 mg/dL, you may be at risk of ketoacidosis (when your body produces high levels of blood acids called ketones), which requires emergency care, according to the ADA.

What to do: If blood sugar levels are too high, exercise can help bring them down. The exception is if your blood sugar is above 240 mg/dL and you have ketones. In this scenario, exercising may spike your blood sugar even higher, according to the ADA. Talk to your doctor about the safest way to lower your blood sugar if this is the case.

Your doctor may also recommend testing your blood sugar throughout the day to keep track of your levels and find out what impact food, exercise, and other activities have on your blood sugar. You should also see your doctor at least twice a year for an A1C test, which gives an overall picture of your blood sugar control over the previous two to three months.

“We strive to keep A1C under 7 percent for most people with diabetes,” says Dr. Wexler. Blood sugar that isn’t well controlled can make it hard to hit that goal.

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Strategies to Control Blood Sugar

There are steps you can take to control blood sugar every day.

Educate Yourself

According to research, people who take an active role in learning about type 2 diabetes and feel confident in their ability to manage the condition are more likely to engage in self-care activities linked to better blood sugar control. This includes taking medication as prescribed, improving your diet, and exercising.

Test Your Blood Sugar on Schedule

According to a review, structured blood glucose monitoring may help you better understand the impact of food and activities on blood sugar levels and improve blood sugar control, which can increase your self-confidence about managing diabetes. Structured monitoring means following a testing schedule set by your doctor, such as checking your blood sugar after you wake up, before and after meals, and before and after exercise. Talk to your doctor about when and how often you should test.

Exercise

Physical activity increases insulin sensitivity, which can help control blood sugar, according to the ADA. Get at least 30 minutes of moderate exercise at least five days a week. How can you tell if the intensity level is moderate? You should be able to talk but not be out of breath or able to sing out loud, according to the ADA.

For the best results, do both aerobic exercise and strength training. The ADA recommends strength training at least twice a week, in addition to 150 minutes of aerobic exercise.

Exercise can lower blood sugar. So keep a source of fast-acting carbohydrates on hand, such as glucose tablets or gels, in case you need to treat hypoglycemia. Test your blood sugar before and after exercise to make sure it’s in a safe range.

Count Carbs

Carbohydrates have the biggest impact on your blood sugar, so monitoring the amount of carbs in your meals can help keep blood sugar levels steady, according to the ADA. Working with a certified diabetes educator or registered dietitian can help you set your personal goals for meals and snacks and master carb counting, says Wexler.

Take Medications as Prescribed

Skipping doses of diabetes medication or taking too much can cause swings in your blood sugar levels. Always take the medication as prescribed. If you’re having trouble sticking to the medication plan, talk to your doctor about changes that can make it easier for you. They may recommend keeping a medication log or setting an alarm or other reminder to take the medication at the same time each day.

Improve Sleep Quality

“There’s evidence that people with sleep apnea and sleep deprivation have impaired glucose tolerance,” Wexler says. According to an article in the Journal of Diabetes, obstructive sleep apnea is more common in people with diabetes and is associated with insulin resistance.

Most adults should aim for seven to eight hours of shut-eye per night. Ask your doctor about doing a sleep study if you wake up several times during the night or frequently have trouble getting out of bed in the morning.

The Takeaway

  • Part of managing type 2 diabetes is dealing with fluctuations in blood sugar — namely, hypoglycemia (low blood sugar) and hyperglycemia (high blood sugar).
  • Both hyperglycemia and hypoglycemia can lead to health complications, which is why it’s important to monitor your blood sugar levels regularly and stick to the type 2 diabetes treatment plan your doctor has recommended for you.
  • Ways to manage type 2 diabetes, maintain better blood sugar control, and stay fit and healthy include taking medication as prescribed; eating a healthy diet; exercising and maintaining other healthy lifestyle habits; and working with your doctor.
EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Diabetes, Heart Disease, & Stroke. National Institute of Diabetes and Digestive and Kidney Diseases. April 2021.
  2. Hypoglycemia (Low Blood Sugar). Cleveland Clinic. January 31, 2023.
  3. Hyperglycemia (High Blood Glucose). American Diabetes Association.
  4. Low Blood Glucose (Hypoglycemia). American Diabetes Association.
  5. What Is the A1C Test? American Diabetes Association.
  6. Juarez LD et al. The Mediating Role of Self-Efficacy in the Association Between Diabetes Education and Support and Self-Care Management. Health Education & Behavior. August 2022.
  7. Holmes-Truscott E et al. The Impact of Structured Self-Monitoring of Blood Glucose on Clinical, Behavioral, and Psychosocial Outcomes Among Adults With Non-Insulin-Treated Type 2 Diabetes: A Systematic Review and Meta-Analysis. Frontiers in Clinical Diabetes and Healthcare. April 20, 2023.
  8. Blood Glucose and Exercise. American Diabetes Association.
  9. Carb Counting and Diabetes. American Diabetes Association.
  10. Loneman SM. Blood Sugar Levels Can Fluctuate for Many Reasons. Mayo Clinic. March 13, 2024.
  11. Bloomgarden Z. Obstructive Sleep Apnea and Diabetes. Journal of Diabetes. November 2023.
  12. How Much Sleep Is Enough? National Heart, Lung, and Blood Institute. March 24, 2022.
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Anna L. Goldman, MD

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Anna L. Goldman, MD, is a board-certified endocrinologist. She teaches first year medical students at Harvard Medical School and practices general endocrinology in Boston.

Dr. Goldman attended college at Wesleyan University and then completed her residency at Icahn School of Medicine at Mount Sinai Hospital in New York City, where she was also a chief resident. She moved to Boston to do her fellowship in endocrinology at Brigham and Women's Hospital. She joined the faculty after graduation and served as the associate program director for the fellowship program for a number of years.

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