High Blood Sugar Basics

High blood sugar, called hyperglycemia, is one of the defining characteristics of diabetes. When people are diagnosed with diabetes, it means their blood sugar has been high, usually for a long period of time.

There are two ways high blood sugar can be monitored:

  • Self-tests using a glucose meter that measures your blood sugar at a specific moment
  • The A1C test performed by your doctor, which shows your average blood sugar level over the past 2-3 months

Over time, high blood sugar can lead to serious long-term health problems. The good news is that scientific studies have proven that control of blood sugar may help delay or even prevent diabetes complications – get started by learning more about the signs and causes of high blood sugar and tips to help prevent its development. Click here to test your knowledge about blood sugar.

What happens when you have high blood sugar?

Insulin is a hormone needed for proper control of blood sugar. Specifically, insulin helps move sugar from your blood into most of your body’s cells, where sugar is used for energy. In patients with type 2 diabetes, the pancreas does not make enough insulin, and/or the insulin that the pancreas makes does not work the way that it should. As a result, sugar in the blood cannot enter most cells and the cells are unable to use this sugar for energy, while the liver makes too much sugar. This in turn, causes blood sugar levels to get too high, which can cause serious long-term health problems.

High blood sugar symptoms

  • When sugar levels become high, you may experience:
    • Dry mouth, unusual thirst
    • Frequent urination
    • Fatigue
    • Blurred vision
    • Headaches
    • Unintentional weight loss

    However, some patients with type 2 diabetes may have no symptoms.

What should I do if I have symptoms?

  • If you haven’t already been diagnosed with type 2 diabetes, see your health care provider for an evaluation
  • If you have diabetes and think you are experiencing any symptoms of high blood sugar, test your blood sugar right away
  • If you are experiencing episodes of high blood sugar, talk with your diabetes healthcare team about ways to help reduce the risk of future episodes, including regular blood sugar monitoring and making potential adjustments to your meal plan, physical activity and medications, when prescribed
  • Click here for more information on what to do if your blood sugar levels are too high

What causes high blood sugar?

  • High blood sugar in people with type 2 diabetes can be caused by the following:
    • Not staying on your prescribed meal plan
    • Insufficient physical activity
    • Not taking your prescribed medicine
    • Stress from any illness, including cold or flu
    • Emotional stress, such as family conflicts or school problems
  • High blood sugar usually occurs over a period of days
  • Over time, your body may make less insulin, which can contribute to high blood sugar. Your treatment plan may need to be adjusted to keep your blood sugar under control. If your blood sugar is high, talk with your diabetes healthcare team about changes to your meal plan and physical activity, and whether adjustments to the medication you take may be necessary. Diabetes is a progressive disease and sometimes changes in medication may be needed to help control your blood sugar. If your doctor decides it is time to change your medication, it may not mean you haven’t tried hard enough – many people need to adjust their treatment plan over time to help them reach their blood sugar goals

Consequences of high blood sugar

  • Short-term complications of high blood sugar can affect daily life and may include fatigue, inability to concentrate and blurred vision. In severe cases, high blood sugar can require emergency treatment
  • Long-term consequences of untreated diabetes can have devastating health effects and include:
    • Heart disease
      Adults with diabetes are 2 to 4 times more likely to have heart disease or suffer a stroke than people without diabetes
    • Kidney disease
      Diabetes is the leading cause of kidney failure
    • Nerve and blood vessel damage
      More than half of all people with diabetes have some form of nerve damage
    • Blindness
      People with diabetes are at an increased risk for eye complications that can lead to blindness
    • Gum disease
      People with diabetes – especially those with poor blood sugar control – are at a higher risk for gum problems

What can I do to control my high blood sugar?

  • To help control high blood sugar, it’s important to set goals with your diabetes healthcare team for weight, physical activity, blood sugar levels and A1C level
  • Stay as close as you can to your schedule of eating, physical activity, and medication
  • Check your blood sugar levels regularly and share your tracking records with your diabetes healthcare team (primary care provider, endocrinologist and diabetes educator)
  • Discuss your latest A1C test results with your diabetes healthcare team to determine whether any adjustments to your treatment plan are needed


Etie Moghissi, MD, FACP, FACE

Dr. Etie Moghissi is a clinical endocrinologist involved in patient care in private practice in Marina del Rey, California, as well as an associate clinical professor of medicine at the University of California, Los Angeles. She is Board Certified in Internal Medicine and Endocrinology and is a member of the board of trustees of the American Collage of Endocrinology.

As a clinical endocrinologist, I treat a number of people with type 2 diabetes and know that managing the disease can be a difficult undertaking. The initial diagnosis is often overwhelming and many patients do not realize that high blood sugar levels over time can lead to serious long-term complications.

That’s why I’m working on the Blood Sugar Basics: Get to Your Goals program to provide you with clear tools and missions that encourage you to know your A1C and talk to your diabetes healthcare team (including your primary care provider, endocrinologist, and/or diabetes educator) about setting and attaining your blood sugar goals.

By working with your diabetes healthcare team, you can develop an individualized treatment plan and learn more about how lifestyle changes, such as meal planning and physical activity, and medication, when prescribed, all play key roles in helping you reach your A1C goal and blood sugar goals. For more advice about type 2 diabetes management and the importance of teaming up with your doctor, click here.

I am very excited about Get to Your Goals and hope that you find it to be a helpful resource. I know how important it is for people with type 2 diabetes to work with their diabetes healthcare team to set personal goals and a plan for achieving them, and that’s exactly where you’ll start with the first mission of Get to Your Goals – Gather Intelligence.