Woman speaking to healthcare provider about what happens when A1c is too high

What Happens When A1c Is Too High?

Written on August 8, 2023 by Lori Mulligan, MPH. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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High A1c levels can be a cause for concern. But before discussing why it is important to know what happens when your A1c is too high, let’s first gain an understanding of what blood glucose is and why we need to measure it. This article will also discuss the purpose of the A1c test, and how it is used to manage diabetics and those at risk of becoming diabetic.

What Is Blood Glucose (Sugar)?

Glucose (sugar) mainly comes from carbohydrates in the food and drinks you consume. It’s your body’s main source of energy. Your blood carries glucose to all of your body’s cells to use for energy.

Several bodily processes help keep your blood glucose in a healthy range. Insulin, a hormone your pancreas produces, is the most significant contributor to maintaining healthy blood sugar.

If you have consistently elevated blood glucose levels (hyperglycemia) — and an elevated A1c as a result — it usually indicates diabetes. Diabetes develops when your pancreas doesn’t make enough insulin or your body isn’t using insulin properly.[1]

A hemoglobin A1c test (HbA1c), or A1c test for short, is a blood test that tells you your average blood glucose levels over the previous two to three months.

This is a standard test that people with diabetes get to assess the overall management of their blood sugar levels and to course-correct treatment plans.

This blood test measures the hemoglobin in your blood. Hemoglobin is a protein found in your red blood cells that gives blood its red color. It carries oxygen throughout your body and is crucial for good health.

This test measures the average amount of blood glucose attached to the hemoglobin in your red blood cells over the past few months. Red blood cells regenerate every three months, which is why the test will only show your average blood glucose level for the previous two to three months.

Who Should Get an A1c Test?

In addition to being used as a means to manage blood sugar in diabetics, A1c tests are also used to screen for people susceptible to becoming diabetic. As such, people with one or more of the following risk factors should get an A1c test [2]:

  • Have a family history of diabetes
  • Are overweight or obese
  • Have hypertension (high blood pressure)
  • Previously had gestational diabetes
  • Are an ethnic minority
  • Have heart disease
  • Have an inactive or sedentary lifestyle

What Do You Do if Your Blood Sugar Is Too High?

The best thing to do when your blood sugar levels are too high is to eat low-carb and high-protein meals and drink a lot of water. Did you forget to take your insulin? You can do a correction bolus or take your medication before you eat. If the high blood sugar continues, contact your doctor and ask them to review your current dosage of insulin or if they need to prescribe another type of medicine for diabetes that will help keep blood glucose levels within the normal range.

Keep testing your blood sugar levels at regular intervals to make sure your high blood sugar is dropping, and if so, not dropping too fast or too much.

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How Do You Feel When Your A1c Is High?

If your blood sugar level is too high, you may experience symptoms such as [3]:

  • Tiredness
  • Increased thirst and frequent urination, or both
  • Nausea or vomiting
  • Dry mouth
  • Blurred vision that doesn't go away when you look at something else
  • Drowsiness to the point of feeling like being drunk

If you feel drowsy, do not drink alcohol because it will make things worse. Drink water instead. Alcohol can cause your blood sugar levels to spike up even more by slowing down how quickly your liver processes food as well as breaking down carbs in high amounts due to the sugars present in alcohol. Drinking too much coffee while high on insulin may also lead to a dangerous drop in blood sugar levels, so try avoiding caffeine if possible until you get back into balance again with medication dosages.

How Can I Tell if My A1c Is High?

Experts who study diabetes have created a range of A1c levels to help you understand where you stand. A1c results are shown in percentages. This number shows you what percent of glycated hemoglobin you have.

For example, if you get an A1c result of 10%, this means you have ten glycated hemoglobins out of every 100 hemoglobins in your blood. The range of A1c levels is:

  • Normal: Under 5.7%
  • Prediabetes: 5.7% to 6.4%
  • Diabetes: 6.5% and above

The higher your percentage, the higher your blood sugar levels. A higher A1c also means a greater risk of developing serious diabetes-related conditions.

Why Is a High A1c Dangerous?

Research shows a strong link between high A1c levels and very serious diabetes complications. These complications include:

  • Coronary artery disease
  • Heart attack
  • Stroke
  • Vision complications (glaucoma, cataracts, retinopathy, macular edema)
  • Blindness
  • Diabetic neuropathy (nerve damage)
  • Kidney disease
  • Gum disease

Again, the higher your A1c, the greater your risk of developing one of these conditions. This is why having a high A1c can be dangerous.[4]

How Can Everlywell Help?

Unfortunately, blood sugar levels tested as a single measurement can vary significantly throughout the day based on many factors, including a recent meal or physical activity.

To get a more precise measurement, an A1c test measures your average blood sugar over a span of two to three months.

This test is used by healthcare providers to help diagnose conditions that result in too much sugar in the blood, such as diabetes, prediabetes, and gestational diabetes.

Everlywell offers an at-home A1c test so you can tell how well your treatment may be working for you.

What Can Cause False High Blood Sugar Readings?

How Much Can I Lower My A1c in a Month?

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  1. A1c. Cleveland Clinic. URL. Accessed on July 21, 2023.
  2. Fallabel C. What is a dangerous level of A1c? Diabetes Strong. Published February 4, 2023. URL. Accessed on July 21, 2023.
  3. High A1c Symptoms: List of warning signs, side effects and simple solutions. Diabeticme.org. Published May 26, 2021. URL. Accessed on July 21, 2023.
  4. My A1c is high. What should I do? Integrative Primary Care. URL. Accessed on July 21, 2023.
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