Low blood sugar with type 1 diabetes

Published Nov. 5, 2018

• Reviewed by a UI Health Care Provider

Low blood sugar can happen if you are taking insulin for your diabetes. It is important to know what can cause low blood sugar and how to treat it. You can prevent low blood sugar by knowing what causes it.

Causes of low blood sugar

Taking too much insulin
Not eating enough carbohydrate after taking insulin
Getting more activity than usual
Drinking alcohol

Signs of low blood sugar

Sweating
Shaking
Pale skin
Pale lips
Very hungry
Weakness
Tired or drowsy
Headache
Irritable or grouchy
Confused
Seizure
Fainting or passing out

Stop what you are doing right away and check your blood sugar if you feel any of these signs.

Low blood sugar for children age 6 and older

A blood sugar less than 70 is too low.

Take 10 to 15 grams of quick-acting carbohydrate right away, such as:
- Drink 3 to 4 ounces of juice
- Drink 3 to 4 ounces of soda pop that has sugar (not sugar-free)
- Chew 3 to 4 glucose tabs
Wait at least 15 to 30 minutes. If you still feel signs of low blood sugar, then recheck your blood sugar.
If your blood sugar is still less than 70, take another 10 to 15 grams of quick-acting carbohydrate.

Low blood sugar for children ages 1 to 5

For young children, a blood sugar less than 80 is too low.

Young children may not know when they feel a low blood sugar.
Adults may notice the child is quiet, sleepy, hungry, or irritable.
Check a blood sugar if your child is acting differently.

If your child’s blood sugar is less than 80:

Give your child 5 to 10 grams of quick-acting carbohydrate right away, such as:
- Drink 2 to 3 ounces of juice
- Eat 2 to 3 ounces of applesauce
Wait at least 15 to 30 minutes. If you still see signs of a low blood sugar, recheck the blood sugar.
If the blood sugar is still less than 80, give your child another 5 to 10 grams of quick-acting carbohydrate.

It is important to use quick-acting carbohydrate. Do not just eat a snack if your blood sugar is too low. Food does not bring the blood sugar up quickly.

If your child’s blood sugar is low at bedtime, always recheck the blood sugar and make sure it is over 90 before falling asleep.

Do not take too much carbohydrate for a low blood sugar because your blood sugar will go too high later on.

What should I do if my blood sugar is low right before a meal?

Take quick-acting carbohydrate.
Wait 5 minutes so your blood sugar starts to come up.
If you are feeling better, take your insulin dose to cover the carbohydrate you will eat.
- Do not take extra insulin to cover the quick-acting carbohydrate you took for your low blood sugar.
Start eating right away.

Will I know if my blood sugar is low while I am sleeping?

During the night you may feel different signs of low blood sugar than when you are awake. It is possible you may not feel a low blood sugar when you are sleeping.

Signs of low blood sugar while you are sleeping are:

Sweating
Pounding heartbeat
Feeling anxious, restless, or having trouble falling asleep
Nightmares
Hunger

If you feel any signs of low blood sugar during the night, do not go back to sleep.

Get up and check your blood sugar.

If your blood sugar is:

Less than 70, take quick-acting carbohydrate
- You might want to keep small boxes or cans of juice at your bedside to treat middle of the night lows.
71 to 100, have a small snack of 5 to 15 grams of carbohydrate

Recheck your blood sugar 1 hour later to make sure it is above 90.

When should I check my blood sugar during the night?

After a day with lots of exercise, such as swimming or sports
If your blood sugar was low before bedtime
When you are sick, especially if you have vomiting (throwing up) or diarrhea
If you have been waking up high every morning for 3 or more days
When your long-acting insulin dose has increased

The best times to check your blood sugar during the night is about 3 to 4 hours after your bedtime snack, then again about 3 to 4 hours after that.