Low Blood Sugar at Night: Diabetes, Night Sweats, What to Do

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Saturday, November 14, 2026 is World Diabetes Day, so here is a night-time side of diabetes that is easy to miss: waking up damp, heart racing, a strange dream still hanging over you, because your blood sugar dropped while you slept. Doctors call it nocturnal hypoglycemia. This guide puts each piece of it on a card you could keep by the bed: what a night low feels like, why it soaks the sheets, how to tell it from a hot flash, what to do and when it is an emergency.

What is low blood sugar at night?

Low blood sugar at night is a drop in blood glucose below the range that is healthy for you while you are asleep, and the medical name is nocturnal hypoglycemia. For most people with diabetes, low means under 70 mg/dL (3.9 mmol/L); for most people without diabetes, under 55 mg/dL (Cleveland Clinic). Your own number may differ, so the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says to check with your care team.

Glucose is your body's main source of energy, and when it drops too low your cells and brain run short, which is why a low brings shakiness and confusion. At night there is an extra problem: NIDDK notes that blood glucose can drop while you sleep and stay low for several hours.

Can low blood sugar cause night sweats?

Yes: sweating is a classic sign of a low, and at night it can be enough to make your pajamas or sheets damp, according to NIDDK. When glucose falls, your body releases the fight-or-flight hormone epinephrine (adrenaline), which brings the thumping heart, sweating, tingling and anxiety of a low (American Diabetes Association). Cleveland Clinic lists the same night pattern: restless sleep, sweat through pajamas or sheets, and nightmares.

What are the signs of low blood sugar while sleeping?

The signs of low blood sugar while sleeping are crying out or nightmares, sweat that dampens your pajamas or sheets, and feeling tired, irritable or confused when you wake, NIDDK says. You may not wake at all. If you do, the ADA and MedlinePlus list:

• Shaking, a fast or pounding heartbeat, sweating, chills or clamminess.
• Hunger, a headache, tingling around the lips or tongue, blurred vision.
• Feeling anxious, irritable or confused, or finding it hard to think.

Everyone's pattern differs, so the ADA suggests writing down the signs after each low and telling the people closest to you what to watch for. Even a low you sleep through can disturb your sleep and make you less likely to notice lows during the day (NIDDK).

Eight words from the chart, one card each

Eight terms you will hear from a diabetes care team, one plain sentence each. Tap a card to see what it means.

Who gets low blood sugar at night?

Night lows mostly affect people who take insulin or pills that push insulin up, and NIDDK adds type 1 diabetes, age 65 or older, a past low, and kidney disease, heart disease or cognitive impairment. In a large global study of people with diabetes who take insulin, 4 in 5 with type 1 and nearly half with type 2 reported a low at least once over four weeks (NIDDK). The common night triggers, from the ADA and NIDDK:

• The dose: too much insulin, the wrong insulin, or an injection into muscle instead of fat.
• Dinner: smaller, later or lower in carbs than the dose was planned for.
• Exercise: it can lower blood glucose for up to 24 hours, including overnight.
• Alcohol: without food it makes glucose harder to keep steady, can mask the first signs, and a low can come hours later.
• Being sick: eating less, or not keeping food down.

What to do depends on who is reading. Pick the line that fits:

Is it a hot flash or low blood sugar?

You often cannot tell a hot flash from a low by feel, because both can bring sweating, a racing heart and broken sleep; the only sure way to know is a glucose check with a meter or CGM (ADA). That matters most for women with diabetes in perimenopause and menopause.

A diabetes-and-menopause leaflet from an NHS hospital trust warns that menopause symptoms can be confused with lows, so test to confirm, or you may take glucose you did not need and run high. Diabetes Self-Management adds that the hormone swings of perimenopause can make blood glucose less predictable. A night sweat from menopause, Cleveland Clinic says, arrives as a sudden wave of heat in the neck, chest and upper body, and you may feel cold after.

Sign	A low	A hot flash
First signs	Shaky, hungry, anxious or clammy	A sudden wave of heat in the neck, chest and upper body
The sweat	Sweating, chills and clamminess	Heavy sweat that can soak clothes and bedding
The heart	A fast heartbeat	A faster heartbeat
In your sleep	Nightmares, crying out, restless sleep	Wakes you hot; you may feel cold after
Next morning	Tired, irritable or confused	Tired after a broken night
What tells them apart	A glucose reading	A glucose reading

More on the hormone side of the night: sleeping hot in perimenopause, even when the room is cold.

What should you do if you wake up with low blood sugar?

If you wake with signs of a low, check your glucose and, if it is under 70 mg/dL or below your target, take 15 grams of fast-acting carbohydrate straight away. This is the 15-15 rule used by the ADA, NIDDK and Cleveland Clinic:

1. Check. If you cannot, the ADA says treat it as a low anyway and check as soon as you can.
2. Take 15 grams of fast carbs: four glucose tablets, one tube of glucose gel, half a cup (4 ounces) of regular juice or soda, or a tablespoon of sugar, honey or corn syrup (NIDDK). Not diet drinks, and not chocolate or peanut butter, whose fat slows it down (ADA).
3. Wait 15 minutes and check again. Still under 70? Another 15 grams.
4. Back in range, and breakfast more than an hour away? Eat a small snack with protein and carbs, such as cheese crackers (ADA, NIDDK).

Two exceptions from NIDDK: on a medicine that slows carbohydrate digestion, use glucose tablets or gel; with kidney disease, pick apple, grape or cranberry juice over orange juice, which is high in potassium.

When is low blood sugar at night an emergency?

A low is an emergency when the person cannot treat it themselves: they cannot be woken, are confused, cannot swallow safely, have a seizure or lose consciousness. The ADA says not to hesitate to call 911, and Cleveland Clinic warns that severe hypoglycemia can be life‑threatening.

Glucagon raises blood sugar by making the liver release stored glucose, and it comes as a ready-to-use pen or nasal powder or a mix-before-use kit (ADA). The person usually comes round in five to 15 minutes and may feel sick, which is why Cleveland Clinic says to roll them onto their side. NIDDK says to teach family and friends how to give it, and to call 911 right after.

Why is my blood sugar low at night but high in the morning?

An early-hours low can make your body release hormones such as cortisol and growth hormone that push blood sugar back up, so you wake up high; this rebound is the Somogyi effect (Healthwise). A high morning reading can also be the dawn phenomenon, a normal rise as your body prepares to wake. To tell them apart, Healthwise suggests checking at bedtime, around 2 to 3 a.m. and on waking for several nights, or wearing a CGM: low at 2 to 3 a.m. points to Somogyi, normal or high to dawn. The fixes differ, so take the readings to your care team rather than adjusting alone.

How can you prevent low blood sugar while sleeping?

You lower the chance of a night low by checking before bed, eating enough at dinner, planning around exercise and alcohol, and asking your care team about the timing of your medicines; not every low can be prevented, Cleveland Clinic says, but the plan can often be adjusted.

• Check before bed, and mid-night after hard exercise or a change such as new insulin or travel across time zones (ADA).
• Ask about a bedtime snack. MedlinePlus says some people need one, and protein snacks may be best.
• Drink with food, never instead of it.
• Use the alarm. If lows are frequent or you no longer feel them, NIDDK says a CGM may be a good option.
• Keep a log of times, readings, medicine, meals and activity; the ADA says that log is how the cause of repeat lows gets found.

Repeat lows can blunt your warning signs (NIDDK); the ADA says avoiding even mild lows for several weeks can help bring them back. Tick what is already by your bed:

Can you have low blood sugar at night without diabetes?

Yes, though it is less common than with diabetes: for most people without it, the body keeps blood sugar in range even through a long fast, and Cleveland Clinic advises anyone with lows who does not have diabetes to see a provider. Causes it names include reactive hypoglycemia two to four hours after eating, heavy drinking without enough food, adrenal insufficiency and rare tumors such as an insulinoma, which most often causes early-morning lows. MedlinePlus adds some non-diabetes medicines and some weight-loss surgery.

Does high blood sugar cause night sweats?

Night sweats are more clearly tied to lows than highs: high blood sugar at night shows up mainly as extra bathroom trips, thirst and headaches (Sleep Foundation), though Cleveland Clinic lists diabetes among conditions that can upset temperature control. Night sweats also come from menopause, infections, thyroid problems, sleep apnea, anxiety, alcohol and many medicines (Cleveland Clinic), and if they keep disrupting your sleep, see a provider. More in the science of night sweats and stress, anxiety and night sweats.

World Diabetes Day 2026: early action, at night too

World Diabetes Day is November 14, and the International Diabetes Federation's 2026 theme is early action on diabetes, focused on early diagnosis and risk reduction (IDF). The IDF says 1 in 9 adults lives with diabetes and type 2 typically develops without obvious symptoms. Early action at night: if you have diabetes, tell your care team about every damp, restless night; if you do not, unexplained night sweats that keep waking you are worth an appointment.

After a damp night: getting comfortable again

Once a low is treated and your reading is back in range, the practical problem is a damp shirt at 3 a.m. Cleveland Clinic's night sweat list includes cold water by the bed, light layers of bedding and loose, lightweight pajamas. Change the layer, not the bed: a dry top takes two minutes, so keep a spare in the drawer with the glucose tablets and put a towel over the damp patch until morning.

To be plain: nothing you wear stops a night sweat, and nothing you wear prevents or treats a low. A layer only changes how the rest of the night feels. Every NightCool piece is made with a fabric that wicks sweat away from the skin, in a loose cut that is easy to pull on half awake.

Want a spare for the nightstand drawer? Sleep in it first. NightCool comes with our 30-Night Cool Sleep Trial: sleep in it, wash it, and if it is not right, start a return within 30 days of delivery. See the trial terms.

The short version

• A night low means under 70 mg/dL for most people with diabetes, or under your own target.
• Sweat, nightmares, crying out and confusion on waking are the classic signs.
• Hot flash or low? Only a reading tells, so check before you snack.
• 15 grams of fast carbs, recheck in 15 minutes, then a small snack. Cannot be woken: glucagon, then 911.

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Sources

1. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Low blood glucose (hypoglycemia). Last reviewed July 2021.
2. Cleveland Clinic. Hypoglycemia (low blood sugar). Medically reviewed, last updated July 28, 2026.
3. American Diabetes Association. Low blood glucose (hypoglycemia): what you need to know.
4. American Diabetes Association. Signs, symptoms, and treatment for hypoglycemia (low blood glucose).
5. American Diabetes Association. Causes and how to prevent hypoglycemia (low blood glucose).
6. American Diabetes Association. Severe hypoglycemia (severe low blood glucose).
7. MedlinePlus Medical Encyclopedia, US National Library of Medicine. Low blood sugar. Review date January 25, 2026.
8. MedlinePlus Medical Encyclopedia. Low blood sugar: self-care. Review date January 25, 2026.
9. Cleveland Clinic. Night sweats. Medically reviewed, last updated April 28, 2026.
10. Sleep Foundation, Danielle Pacheco. Diabetes and sleep. Medically reviewed by Abhinav Singh, MD. Updated July 15, 2025.
11. Healthwise (via Cigna). Dawn phenomenon and the Somogyi effect. Current as of April 13, 2022.
12. Diabetes Self-Management. Menopause: how to manage your diabetes. Updated September 12, 2024.
13. Chelsea and Westminster Hospital NHS Foundation Trust. Diabetes and the menopause (patient leaflet).
14. International Diabetes Federation. World Diabetes Day: early action on diabetes, 14 November.

This article is general information about low blood sugar, night sweats and sleep, not medical advice, and it does not replace your own diabetes plan. If you have lows at night, wake up soaked and do not know why, or are unsure what number is low for you, talk to your doctor or diabetes care team. In an emergency, call 911.