A glycated hemoglobin A1c test (HbA1c), or A1c test for short, is a blood test that tells you your average blood glucose levels over the previous 2-3 months. 

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

But what is a dangerous level of A1c? This article will investigate A1c levels that are considered both too low and too high, and what to do about improving yours if it is at a dangerous level. 

What Is a Dangerous Level of A1c?

What is an A1c? 

An A1c is a blood test that is typically taken in a laboratory and measures the hemoglobin in your blood. 

Hemoglobin is a protein found in your red blood cells and 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 3 months, which is why the test will only show your average blood glucose level for the previous 2-3 months. 

It is usually skewed toward the preceding several weeks before a test. 

What is the importance of an A1c? 

An A1c test helps diagnose diabetes

The A1c is an important tool for diagnosing type 1 and type 2 diabetes, prediabetes, and even sometimes gestational diabetes.

If your results reveal prediabetes, your doctor will probably recommend that you get a repeat A1c test done annually or semi-annually.

Additionally, for people 45 and older, the Centers for Disease Control and Prevention (CDC) recommends getting an A1c test. 

If the results are normal, testing will be repeated on a schedule determined by your doctor based on your age and risk factors. If the test shows prediabetes, A1c testing will likely be recommended every 1 or 2 years.

If you have prediabetes, you should talk with your doctor about steps you can take to reduce your risk of developing diabetes. 

Your doctor may recommend you get an A1c test if you’re under the age of 45 but have certain risk factors for diabetes, including: 

  • Being overweight or obese
  • Having a family history of diabetes
  • Having hypertension (high blood pressure)
  • Previously had gestational diabetes 
  • Are an ethnic minority 
  • Having heart disease
  • Live a sedentary lifestyle/physical inactivity 

You should call your doctor right away if you experience the following symptoms, as they are signs of diabetes: 

Your doctor may recommend you get an A1c test or seek emergency medical care, depending on the severity of your symptoms.

You can also test your A1c at home with a test kit you can buy at your local pharmacy or online.

An A1c test determines general diabetes control 

For people with existing diabetes, a quarterly A1c test is usually ordered to determine your average blood sugar levels, and general diabetes control, over the previous 3 months. 

A1c tests are great at detecting if your blood sugars are consistently running high or low, and can help you change your diabetes therapies to help prevent complications such as heart disease, retinopathy, neuropathy, kidney disease, and premature death.

However, since an A1c test is merely an average of your previous 3 months’ blood sugar levels, it will average out all of the high blood sugar levels with all of the low blood sugar levels. This can potentially give you a false sense of accomplishment if, in fact, you’re just riding the blood sugar rollercoaster most days! 

If, however, your blood sugar levels are moderately stable, it can give you a great sense of how well you’re managing to keep your blood sugars in range. 

What are the different A1c levels? 

The American Diabetes Association uses the following definition to determine if you have diabetes or prediabetes:

  • Normal, no diabetes: A1c below 5.7%
  • Prediabetes: A1c between 5.7% and 6.4%
  • Diabetes: A1c of 6.5% or higher 

Individual A1c goal levels will vary by person. For example, for someone who doesn’t detect their low blood sugars, or for someone with diabetes who lives alone, their doctor may recommend a slightly higher A1c. 

On the other hand, for someone with existing diabetes who is pregnant, an A1c of or below 6% is ideal, as long as they’re not experiencing too many low blood sugars. 

American Diabetes Association  (ADA) advises A1c levels to stay below 7% to help prevent diabetes complications for adults, and below 7.5% for children. 

What is a dangerous A1c level? 

There are dangers to having both a too-high and a too-low A1c level. Always work with your doctor to see what A1c level should be your goal, depending on your lifestyle, health goals, and life stage. However, some dangerous ranges would be best to avoid.

An A1c lower than 5% 

While diabetes management is becoming more precise with faster insulins, closed-loop insulin pumps, continuous glucose monitoring (CGM) systems, and better access to diabetes self-management education (DSME), people with diabetes are achieving lower A1cs than ever before. 

This is a great accomplishment if you’re not experiencing too many low blood sugars. 

Remember, an A1c is just an average blood sugar of the previous three months, so if your A1c is lower than 5%, that may be an indicator that you’re having too many lows. 

Even if you’re not experiencing severe low blood sugar that often if you’re older, live alone, have trouble detecting your low blood sugars (have hypo-unawareness), or do not have a continuous glucose monitor (CGM) with low alerts set on, it can be dangerous to have an A1c that low. 

A 5% A1c indicates that your average blood sugar is only 97 mg/dL. 

This means that even a moderate walk or hot shower could send your blood sugar plummeting at any minute, which can be risky. 

Low blood sugars can lead to severe diabetes complications, including diabetic coma and death, so it’s crucial that you prevent severe low blood sugars and have fast-acting glucose or glucagon available in case of an emergency. 

If you live alone, are older, have hypo-unawareness, do not have a CGM, or are simply experiencing too many lows, talk with your doctor about lowering your insulin doses to help prevent dangerous lows and increase your A1c. 

To note: Pregnant women may have an A1c under 5%, and if they’re not experiencing many low blood sugar levels, this may be fine. 

Additionally, at the beginning of a type 1 diabetes diagnosis, many people experience what is known as the “honeymoon phase” where their pancreas is still emitting some insulin, and they may have an extremely low A1c for the first several months to a year after diagnosis. 

This is normal, but if you’re in the honeymoon phase with too many low blood sugars, talk with your doctor. 

An A1c higher than 7% 

While the ADA recommends that most adults maintain an A1c of 7% or lower (and children maintain an A1c of 7.5% or lower), this isn’t always possible. 

Competing priorities, money, time, energy, hormones, jobs, school, stress, and everyday life make managing diabetes really hard, and sometimes we struggle with higher-than-ideal blood sugar levels and that is okay! 

An A1c is 7% is an average blood sugar level of 154 mg/dL and an A1c 0f 7.5% is an average blood sugar level of 169 mg/dL, both of which are reasonable numbers (especially if you’re a child who is wont to not always finish meals or an adult who struggles to detect dangerous low blood sugars). 

Most times, especially during busy or stressful times of life, an A1c of between 7-8% is not dangerous and won’t pose any problems for your health. 

An A1c higher than 9% 

However, numbers much higher than 9% can start to put you at risk for diabetes complications later on in life. 

According to the American Diabetes Association’s Standards of Medical Care in Diabetes, 2022, an A1c of 9% puts one at a higher risk for blindness, heart attack, nerve damage, and kidney failure. 

An A1c is 9% is equal to an average blood sugar level of 212 mg/dL. 

The higher your A1c, the more dangerous it is and the more likely you are to suffer from diabetes complications. 

The following are A1c levels to average blood sugar levels: 

10 % = 240 mg/dL

11% = 269 mg/dL

12% = 298 mg/dL

13% = 326 mg/dL

14% = 355 mg/dL 

For more detailed information, read How to Translate Your A1c to a Blood Sugar Level.

Prolonged high blood sugars over time can lead to severe diabetes complications, such as retinopathy, neuropathy, heart disease, kidney disease, lower-limb amputations, stroke, and even premature death. 

If you’re struggling to lower your A1c, talk to your doctor about increasing or changing your medication regimen, diet, physical activity level, addressing any mental health issues, or if they suggest other ways to help you better manage your blood sugar levels. 

To note: at diagnosis, especially with type 1 diabetes, a person will typically have an extremely elevated A1c level. 

This does not automatically mean that you will suffer long-term diabetes complications. Usually, after a few months of insulin therapy and treatment, A1c levels drop extremely quickly and there is no risk of serious future complications. 

Ways to make your A1c safer 

There are ways to both increase and decrease your A1c if you’re falling into the danger zone. 

If your A1c is too low 

  • Work with your doctor to decrease your medications and/or insulin
  • Decrease the amount of exercise you do, if you’re struggling with lows after physical activity
  • Increase the amount of protein and fat in your diet to help prevent low blood sugars overnight
  • If you don’t already have one, use a CGM to catch low blood sugar levels before they become dangerous
  • Utilize an insulin pump and use temporary basal settings for things like exercise and other physical activity to help prevent low blood sugars 

If your A1c is too high 

  • Work with your doctor to increase your medications and/or insulin 
  • Increase the amount of physical activity you do each day
  • Eat lower carbohydrate meals and eat plenty of whole foods with fiber
  • If you struggle with counting carbohydrates, start a food journal and work with a registered dietitian (RD) to help you meal plan 
  • Avoid processed foods and foods and drinks with added sugar 
  • Check your blood sugar multiple times a day, or utilize a CGM to help catch high blood sugars sooner
  • Utilize an insulin pump that can use different basal rates throughout the day and night to help prevent prolonged high blood sugars 
  • Get plenty of sleep (aim for between 7-9 hours per night for better insulin sensitivity) 
  • Manage stress with yoga, meditation, and breathing to decrease insulin resistance 

Summary

While there is a lot of talk about the dangers of a high A1c, there isn’t much talk about the dangers of a low A1c, and there is a lot of confusion as to what is actually dangerous and what to do about it. 

For most people, a good and safe A1c lies anywhere between 5-8%, although this will vary from person to person. 

If you’re pregnant, your A1c should be lower, and if you live alone or struggle with low blood sugars, your doctor may want your A1c on the higher end. 

However, an A1c that is routinely under 5% can pose a danger of too many and too severe low blood sugars, which can cause diabetic coma and death. 

An A1c of 9% or above increases your risk for diabetes complications, including heart disease and heart attack, stroke, retinopathy and blindness, nerve damage and amputation, kidney disease and kidney failure, and ultimately, premature death. 

Work with your doctor to adjust your medications, increase or decrease your physical activity, alter your diet, and better regulate sleep and stress to help you land your goal A1c. 

While there is no “perfect” A1c, no one should have to live with an A1c at a dangerous level that is harmful to one’s health and well-being.