Low Blood Sugar at Night: Nocturnal Hypoglycemia

Low blood sugar at night is a common danger for people with diabetes. It is important for both you and your sleep partner to know the warning signs and have a plan for treatment.

awake at night nocturnal hypoglycemia

Untreated hypoglycemia can lead to a seizure and be life-threatening.

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You know it is important to have tight control of you blood sugar with diabetes. Tight control is how you prevent diabetes complications. One of the dangers of tight control is letting your blood sugar get too low, called hypoglycemia. [1]

The most dangerous time for hypoglycemia is when you are sleeping, a condition called nocturnal hypoglycemia. Up to 50 percent of diabetics may have episodes of nocturnal hypoglycemia. [1] In fact, almost 50 percent of hypoglycemic episodes occur at night and more than half of dangerous episodes occur at night. [2]

Risk of Nocturnal Hypoglycemia

Nocturnal hypoglycemia is most dangerous for people who take insulin, but it can also happen to people with type 2 diabetes who take oral diabetes medications. [1] You could be at risk if you: [1-3]

  • Skip dinner or have too little to eat before bedtime
  • Exercise before bedtime
  • Drink alcohol at night
  • Have a past history of nocturnal hypoglycemia
  • Are sick
  • Take NPH insulin, which has its peak affect in about 6 to 8 hours
  • Have recently changed your insulin medication
Nocturnal Hypoglycemia

Early morning wake-up calls often are simply one of many low blood sugar symptoms.

Symptoms of Nocturnal Hypoglycemia

It is important for both you and your sleeping partner to know the warning signs. Sleeping through the warning signs is especially dangerous because your blood sugar may go lower before you can correct it. [1-3] If you sleep alone, you may be at higher risk. [1]

Warning signs occur when your blood sugar drops below 70 mg/dl. When this happens, your body releases hormones like glucagon and epinephrine to increase your blood sugar. This causes warning signs like a racing heart, sweats, and tremors. These warnings are your body’s way of telling you to get more sugar into your system quickly. [1] Hopefully they will wake you from sleep, but some people sleep through. [1-3]

If hypoglycemia wakes you up, these are the symptoms: [1-3]

  • Being cold and clammy or hot and sweaty
  • Feeling shaky and trembling
  • Waking from a nightmare
  • Increased or slowed breathing
  • A pounding or racing heart
  • Waking up with a headache

Your sleeping partner should wake you if he or she notices any of the warning signs or if you are more restless, noisy, or breathing irregularly in your sleep. [2]


Untreated hypoglycemia can lead to a seizure and be life-threatening. [1] Both you and your sleep partner should be prepared to treat this condition. If you wake up with signs of hypoglycemia, or if your sleep partner wakes you and you are aware enough to manage low blood sugar, check your blood sugar with your glucose monitor. [1-3]

If your blood sugar is low, eat some hard candy, drink 4 to 5 ounces of fruit juice, or take 3 to 4 glucose tablets. Retest your blood sugar. If you are still low, have a snack with a carbohydrate and a protein, like whole wheat with peanut butter. Call your doctor to report your hypoglycemic episode in the morning. [1-3]

You should also ask your doctor if you should get an emergency glucagon kit. If you are at risk for hypoglycemia, your sleeping partner could use this kit to treat a hypoglycemic episode if your partner can’t wake you. The kit is a syringe with glucagon that your partner can learn to use for an emergency  glucagon injection. If you don’t have a glucagon kit and your partner is unable to wake you from a suspected episode of hypoglycemia, your partner should call 911. [2]

How to Prevent Nocturnal Hypoglycemia

Start by talking to your doctor about a bedtime blood sugar target. Ask about your risk for hypoglycemia and if you should get a glucagon kit. Don’t miss dinner, exercise before bedtime, or drink alcohol at night. Have a sugar and protein snack before bedtime, like a wheat cracker with cheese. [1-3]

If you have had symptoms of nocturnal hypoglycemia, work with your doctor on a prevention plan. This may include switching to a longer acting insulin that does not peak during sleep, or changing your insulin dose. You might be asked to set an alarm and check your blood sugar in the early morning for a while.  For people at high risk for nocturnal hypoglycemia, a continuous glucose monitor (CGM) may be the best solution. A CGM can check your blood sugar every 5 minutes and can set off an alarm if your sugar gets too high or too low. [1-3]



  1. Type2Diabetes.com, Nocturnal Hypoglycemia
  2. Johns Hopkins Medicine, Nocturnal Hypoglycemia
  3. North Shore University Health System, Nocturnal Hypoglycemia

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Chris Iliades, MD

Dr. Chris Iliades is board-certified in Ear, Nose and Throat and Head and Neck Surgery from the American Board of Otolaryngology and Head and Neck Surgery. He holds a medical … Read More

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