The rule of 15 is a strategy to treat mild hypoglycemia. However, if you have severe hypoglycemia, you should consider recommended alternatives or get medical attention.

Hypoglycemia happens when your blood sugar drops below what your healthcare professional discussed as a normal level. In mild cases, it can cause symptoms such as shakiness, confusion, and lightheadedness.

Anyone can experience hypoglycemia, but it’s particularly common among people with diabetes who take insulin.

Medical professionals often recommend treating mild low blood sugar by following the rule of 15, also known as the 15-15 rule.

This rule advises consuming 15 grams (g) of carbohydrates when your blood sugar drops under 70 milligrams/deciliters (mg/dL) and then checking your blood sugar again after 15 minutes have elapsed. If your blood sugar is still low, you repeat the process.

In this article, we take a closer look at how you can use the 15-15 rule to manage low blood sugar.

Many medical professionals recommend following the 15-15 rule when your blood sugar is between 55 and 69 mg/dL. If your blood sugar is below 55 mg/dL, the 15-15 rule might not work.

Here’s how the rule of 15 works:

The rule of 15

  1. Consume 15 g of simple carbohydrates, such as glucose tablets or 1/2 cup (4 ounces) of full-sugar orange juice.
  2. Wait 15 minutes and measure your blood sugar level again.
  3. If your blood sugar is still between 55 and 69 mg/dL, consume another 15 g of carbohydrates.
  4. Keep repeating until your blood sugar is above 70 mg/dL.

Young children often do not need 15 g of carbohydrates. According to the American Diabetes Association:

  • infants may only need 6 g
  • toddlers may only need 8 g
  • small children may only need 10 g

These are only guidelines, as the amount of carbohydrates depends on the individual child. Your child’s diabetes team can help you develop an optimal rule of 15 for your child.

The rule of 15 should not be followed when your blood sugar is below 55 mg/dL.

Best types of carbohydrates to raise your blood sugar

When you’re trying to raise your blood sugar quickly, it’s best to stick to foods that are made up of mostly simple sugars. Foods with a lot of fiber or fat take longer to break down.

Here are some examples of simple carbohydrates you can use to raise your blood sugar, with approximate portion sizes to get 15 g of sugar:

  • 3 to 4 glucose tablets
  • 1/2 cup (4 oz) of regular soda or juice
  • 1 tablespoon of sugar, syrup, or honey
  • 1 dose of glucose gel

After eating carbohydrates, your digestive system breaks them down into a type of sugar called glucose. Glucose travels from your digestive system into your bloodstream and then circulates around your body to provide your tissues and organs with energy.

Hypoglycemia is when your blood glucose level drops below what your healthcare professional discussed as a normal blood sugar level. A reading below 70 mg/dL is considered low, and a level below 55 mg/dL is considered extremely low.

Your brain depends mostly on glucose for energy. When your blood sugar drops, it’s common to experience cognitive symptoms such as impaired judgment and difficulty concentrating. If left untreated, your blood sugar can drop to a dangerously low level which can lead to coma or death.

What is hypoglycemia unawareness?

About 25 percent of people with type 1 diabetes and 10 to 15 percent with type 2 diabetes who use insulin or sulfonylureas medications experience hypoglycemia unawareness.

Hypoglycemia unawareness is when you have trouble perceiving the symptoms of hypoglycemia you’re experiencing. It may lead to you not addressing the condition promptly, putting yourself at a higher risk of developing severe hypoglycemia.

Severe hypoglycemia below 55 mg/dL is too low to treat with the rule of 15. This is partly because, depending on your symptoms, you may not be able to treat yourself or measure your own blood sugar levels.

According to the Centers for Disease Control and Prevention (CDC), injectable glucagon is the best way to treat severe low blood sugar. Glucagon is a hormone produced by your pancreas that stimulates the release of glucose from your liver into your bloodstream.

Glucagon kits are available by prescription. You can speak with your doctor about whether you need a kit.

It’s important to treat low blood sugar as soon as you notice symptoms. This can help prevent it from dropping to a severely low level.

Symptoms of mild low blood sugar include:

If your blood sugar drops while you’re sleeping, you may experience symptoms such as:

  • crying out or having nightmares
  • feeling tired, confused, or irritable after waking
  • sweating through your pajamas or your sheets

Severe low blood sugar can cause:

People who take insulin to treat diabetes are more likely to experience low blood sugar. Many factors can contribute to the development of low blood sugar including:

  • going too long without consuming carbohydrates
  • going without eating for an extended period of time
  • taking too much insulin
  • consuming less carbohydrates than what’s necessary to balance your insulin
  • taking your insulin at the wrong time
  • consuming too much alcohol
  • increasing physical activity, such as exercising more
  • traveling to high altitudes
  • experiencing hot or humid weather
  • taking certain diabetes medications, such as gliclazide and glimepiride

You can minimize your chances of developing low blood sugar by:

  • tracking your blood sugar levels regularly
  • keeping a sugary snack on hand consistently, such as glucose tablets or a juice box
  • eating meals on a regular schedule — do not skip meals
  • eating a snack before engaging in physical activities like exercising
  • asking your doctor if you should take less insulin before intense exercise
  • avoiding consuming large amounts of alcohol
  • checking your blood sugar levels more often, especially in conditions that caused low blood sugar in the past

Many medical professionals recommend following the rule of 15, also known as the 15-15 rule, when you have low blood sugar.

To follow this rule, you consume 15 g of simple carbohydrates and wait 15 minutes before measuring your blood sugar level again. If your blood sugar is still low, you can repeat the process.

The 15-15 rule should not be used to treat severely low blood sugar. If your blood sugar is severely low, you may need a glucagon injection. Talk with your doctor about whether you should have a prescription glucagon kit handy.

Sources
Low blood glucose (hypoglycemia). (2021). https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia
Low blood sugar (hypoglycaemia). (2023). https://www.nhs.uk/conditions/low-blood-sugar-hypoglycaemia/
Low blood glucose (hypoglycemia). (n.d.). https://diabetes.org/living-with-diabetes/treatment-care/hypoglycemia
Rix I, et al. (2019). Glucagon physiology. https://www.ncbi.nlm.nih.gov/books/NBK279127/
Seaquist E. (2023). How hypoglycemia unawareness affects people with diabetes. https://www.niddk.nih.gov/health-information/professionals/diabetes-discoveries-practice/how-hypoglycemia-unawareness-affects-people-with-diabetes
Severe hypoglycemia (severe low blood glucose). (n.d.). https://diabetes.org/living-with-diabetes/hypoglycemia-low-blood-glucose/severe
Treatment of low blood sugar (hypoglycemia) (2024). https://www.cdc.gov/diabetes/treatment/treatment-low-blood-sugar-hypoglycemia.html