Hypoglycemia and Sick-Day Rules: The Rule of 15, Glucagon, and Ketone Checks

Who needs this teaching

Clients who take insulin or a sulfonylurea, and the family members who help in an emergency. Hypoglycemia results from too much insulin for the food eaten and the activity performed. Illness raises glucose through stress hormones and increases the risk of diabetic ketoacidosis and hyperosmolar hyperglycemic state.

The priority teaching points

1. Recognition. Hypoglycemia is glucose under 70 mg/dL; glucose under 54 mg/dL is clinically significant hypoglycemia. Adrenergic signs are tremor, diaphoresis, tachycardia, anxiety, and hunger. Neuroglycopenic signs are headache, blurred vision, confusion, slurred speech, irritability, and seizures. Beta blockers mask tachycardia and tremor. Clients with hypoglycemia unawareness have no early warning signs. Check glucose when symptoms appear; without a meter, treat.
2. Rule of 15. Take 15 g of fast-acting carbohydrate: 4 oz (1/2 cup) of juice or regular soda, 3 to 4 glucose tablets, or 1 tablespoon of sugar or honey. Recheck in 15 minutes. Repeat if glucose remains under 70 mg/dL. Once glucose is normal, eat a snack with carbohydrate and protein if the next meal is more than 1 hour away. Do not treat with chocolate or other high-fat foods; fat slows glucose absorption.
3. Glucagon. Glucagon is prescribed for clients who take insulin or have a high risk of hypoglycemia. Teach the family to give nasal or injectable glucagon when the client is unconscious, has a seizure, or cannot swallow safely. Never put food or fluid in the mouth of a client who cannot swallow. Turn the client on the side, because vomiting is common after glucagon. Call 911.
4. Prevention. Eat meals and snacks on schedule. Check glucose before exercise and before driving. Drink alcohol only with food; alcohol inhibits hepatic glucose production and causes delayed hypoglycemia. Carry fast-acting carbohydrate and wear medical identification.
5. Sick-day medications. Continue insulin during illness, including on days the client eats less. Illness often increases insulin needs. Never stop long-acting insulin without provider instructions. Follow the written sick-day plan for other diabetes medications.
6. Sick-day monitoring. Check glucose every 2 to 4 hours. Check urine or blood ketones when the client has type 1 diabetes or glucose over 250 mg/dL. Report moderate or large ketones.
7. Fluids and food. Drink at least 8 oz (240 mL) of sugar-free fluid every hour while awake. When the client cannot eat usual meals, replace them with carbohydrate liquids or soft foods, such as juice, regular soda, regular gelatin, or crackers with soup.

Red flags the client reports

Teach-back questions

• "What will you eat or drink if your glucose is 62?"
• "When will you recheck your glucose after treating a low?"
• "Show me how you will give the glucagon." (family member)
• "Will you take your insulin if you cannot eat because you are sick?"
• "When will you check for ketones?"

Teaching tips

• Have the client keep fast-acting carbohydrate at home, in the car, and at work.
• Practice with a glucagon training device with the family.
• Write the sick-day plan and the contact number on the handout.
• Review the medication list for beta blockers and sulfonylureas.

Read more on NCLEXPace

• Insulin: Types, Timing, and the Questions Built On Them
• Diabetes Emergencies: DKA vs HHS, Step by Step
• Antidotes and Reversal Agents: The Only List You Need

Sources

• Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Diabetes.
• American Diabetes Association Professional Practice Committee. Standards of Care in Diabetes-2025. Diabetes Care. 2025;48(Suppl 1).
• Glucagon for Injection and Glucagon Nasal Powder: FDA prescribing information (DailyMed).