When Low Blood Sugar Has No Symptoms

From the WebMD Archives

No one with diabetes welcomes signs of low blood sugar, also known as hypoglycemia. Sweating and feeling shaky, dizzy, moody, and anxious are signs that your blood sugar is dropping. You know you must treat it quickly.

But what if your body stops giving you these warning signs? Not being able to feel low blood sugar is known as hypoglycemic unawareness. If you have it, you could pass out without ever knowing that your blood sugar has dropped.

Read on to learn what makes it more likely and how to avoid it.

Who Gets Hypoglycemic Unawareness?

If you have diabetes, you can have low blood sugar -- whether you take insulin or other drugs to control it. It's most likely if you have type 1 diabetes. Once you have low blood sugar, it's harder for your body to respond to it in the future.

If you have type 1 diabetes, you're also more likely to stop feeling low blood sugar. But it can happen if you have type 2 diabetes, too. The longer you’ve had diabetes, the more common it is. The symptoms can start to fade after you've had diabetes for as little as 5 years. After 20 years, they may be too faint for you to notice. Or you may only have them after your blood sugar drops very low.

You're also more likely to have hypoglycemic unawareness if:

  • You have neuropathy, or damage to the parts of the nervous system that trigger your body’s response to low blood sugars.
  • You have strict blood sugar control and you are on an intensive insulin regimen (3 or more insulin shots a day), have a history of severe low blood sugar that requires aid from another person, or had recent low blood sugar.
  • You take drugs for your heart or high blood pressure that can mask your body's response to low blood sugar.

What Causes Hypoglycemic Unawareness?

When your blood sugar starts to drop too low, your body normally stops releasing insulin and starts releasing other hormones. These include glucagon and epinephrine. These hormones help keep your blood sugar stable.

Epinephrine is the same hormone that helps us during our “flight or fight” response. It causes the symptoms that people with diabetes usually feel when sugars start to drop. But if you keep having low blood sugars, your reaction to them will be blunted. If you don't feel the symptoms that signal low blood sugar, you may not know that your glucose levels are dropping. If your blood sugar levels get too low, you may pass out or have seizures and need emergency treatment.


Help for Hypoglycemic Unawareness

See your doctor if you aren’t feeling the signs that should occur when low blood sugar is coming on. You may be able to feel it again within weeks. Your doctor can create the best treatment plan for you.

Your doctor may suggest that you:

  • Set your target levels for blood sugar higher than usual. This is usually done for a few weeks.
  • Test your blood sugar more often. You may need to check it around bedtime, exercise, or meals, or more often during illness or stress. Your doctor may tell you to test it at other times, too.
  • Use a continuous glucose monitor. You'll still need to monitor your blood sugar and prick your finger. But this type of monitor may help you spot patterns or trends easier. This can help you better manage your diabetes.
  • Lower your chances of hypoglycemia. Go over the things that make low blood sugar more likely and take steps to make it less likely for you. For instance, you may need to adjust your insulin doses to better match your diet and exercise. Or you may need to be more regular with your meals and how many carbohydrates you have at them

Know Other Symptoms of Hypoglycemia

Even if you don't have the body symptoms of low blood sugar, you'll still have:

  • Trouble focusing
  • Slowed speech
  • Slowed thinking
  • Clumsiness

When these symptoms start to appear, you'll be at a blood sugar level where you can still treat hypoglycemia on your own. They are subtler than the classic symptoms, but if you know what times of day your blood sugar often drops, you can watch for them.

Preventing Hypoglycemic Unawareness

The only way to keep from having hypoglycemic awareness is to avoid having low blood sugar as much as you can. These steps may help:

  • Talk with your doctor about your target blood sugar level.
  • Check your blood sugar levels often and know what things may affect them.
  • Recheck and treat low or dropping sugar levels, even if you feel OK.
  • Let your friends and family know that you could get hypoglycemic unawareness. Teach them the signs to watch for and how to treat it.

WebMD Feature Reviewed by Brunilda Nazario, MD on February 14, 2014



American Diabetes Association: "Hypoglycemia (Low blood glucose)."

Joslin Diabetes Center: "What Can I Do to Prevent Serious Hypoglycemic Episodes When I am Hypoglycemic Unaware?"

National Institute of Diabetes and Digestive and Kidney Diseases: "Hypoglycemia."

Vivian Fonseca, MD, FRCP, chief of endocrinology, Tulane University School of Medicine, New Orleans.

Martin Abrahamson, MD, chief medical officer, Joslin Diabetes Center, Boston.

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