The Rule of 15 for Low Blood Sugar
The rule of 15: eat or drink 15 grams of fast-acting carbohydrate, wait 15 minutes, check your blood sugar again, and repeat if it is still below 70 mg/dL (3.9 mmol/L). It is for a person who is awake and can swallow. Follow any plan your care team gave you.
The steps
- Check. If your glucose is below 70 mg/dL (3.9 mmol/L), or you have symptoms of a low, treat it. (Symptoms)
- Take 15 grams of carbohydrate that works quickly. The ADA says glucose is the preferred treatment; any carbohydrate that contains glucose may be used. Avoid high-fat or high-protein foods for this step.
- Wait 15 minutes, then check again.
- Repeat with another 15 grams if you are still below 70 mg/dL (ADA Recommendation 6.15).
- Once you are up, ask your care team what to eat next and tell them about the low.
The NIDDK words it as 15 to 20 grams and notes that you should keep treating until you are back in your target range. The ADA says 15 grams for most people and 5 to 10 grams for people using automated insulin delivery systems, unless the low happens with exercise or a meal dose was greatly overestimated. Those exceptions are for your care team to explain.
What counts as 15 grams
| Option | Amount | Source |
|---|---|---|
| Glucose tablets | Four tablets (check the label; many are 4 g each) | NIDDK; product labels |
| Glucose gel | One tube (check the label) | NIDDK |
| Fruit juice, not low-calorie | ½ cup (4 ounces) | NIDDK |
| Regular soda, not diet | ½ can (4 to 6 ounces) | NIDDK |
| Sugar, honey or corn syrup | 1 tablespoon | NIDDK |
Amounts are the NIDDK’s examples for 15 to 20 grams. Brands differ, so read the label. If you have kidney disease, the NIDDK suggests apple, grape or cranberry juice instead of orange juice because of its potassium.
Glucose tablets are the easiest to carry, with a known amount on the label. See glucose tablets.
Why the wait is 15 minutes
It takes time for carbohydrate to be absorbed and reach the blood. Taking more too soon can overshoot and leave glucose high. Both the ADA and the NIDDK use a 15-minute recheck. Sit down while you wait. If you are driving, stop safely first.
What not to do
- Do not give food or drink to someone who cannot swallow or who is not alert.
- Do not give insulin to someone who has low blood sugar (ADA).
- Do not treat a low with high-fat or high-protein food alone.
- Do not ignore repeated lows. Write them in the blood sugar log and show your care team.
Learn about the severe-low treatment on the glucagon page.
Frequently asked questions
What is the rule of 15 for low blood sugar?
Eat or drink about 15 grams of fast-acting carbohydrate, wait 15 minutes, check your blood sugar again, and repeat if it is still below 70 mg/dL (3.9 mmol/L). It is the standard first step for a mild or moderate low in a person who can swallow safely.
Is it 15 grams or 15 to 20 grams?
The ADA Standards of Care say 15 grams for most people. The NIDDK says 15 to 20 grams. Your care team may give you a specific amount; follow it. People using an automated insulin delivery system are typically told to use 5 to 10 grams (ADA).
Which foods count as 15 grams?
The NIDDK lists four glucose tablets or one tube of glucose gel, half a cup (4 ounces) of fruit juice that is not low-calorie, half a can (4 to 6 ounces) of regular soda, and one tablespoon of sugar, honey or corn syrup. Check labels for the grams of carbohydrate.
Why not chocolate or a sandwich?
The ADA says to avoid high-fat or high-protein foods for the initial treatment, because fat and protein slow how fast sugar reaches the blood. Plain glucose or sugar works fastest.
What if I cannot swallow or I pass out?
Do not put food or drink in the mouth. This is a severe low: call 911. If glucagon is available and someone is trained, it is the best treatment, per the NIDDK. See the glucagon page.
Information only, not medical advice. Your care team may set different targets for you, and only a lab test ordered by a clinician can diagnose diabetes or prediabetes. See our medical disclaimer.
Sources
- ADA Standards of Care in Diabetes—2026, Section 6: Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises
- NIDDK: Low Blood Glucose (Hypoglycemia)
- CDC: Low Blood Sugar (Hypoglycemia) symptoms
Last reviewed: by the Diabetes Blogs editorial team. Information only, not medical advice.
