T1D glossary

15-15 rule

Also called 15/15 rule, rule of 15.

The 15-15 rule is the CDC's published way to treat a low: have 15 grams of carbs, wait 15 minutes, then check again. If glucose is still under 70 mg/dL (3.9 mmol/L), repeat. CDC notes young children may need less than 15 grams, and ADA names glucose as the preferred treatment for a person who is awake. (CDC; ADA Standards of Care 2026, section 6)

Worked example

At 62 mg/dL (3.4 mmol/L): 15 g of carbs, then a check 15 minutes later. At 66 mg/dL (3.7 mmol/L), still under 70, the step repeats. At 84 mg/dL (4.7 mmol/L), the low is over.

Related terms

• Level 1 hypoglycemia
• Level 2 hypoglycemia
• Glucagon

Sources, quoted

• CDC: “follow the 15-15 rule: Have 15 grams of carbs, then wait 15 minutes.”
• CDC: “Check your blood sugar again.”
• CDC: “If it's still less than 70 mg/dL, repeat this process.”
• CDC: “Young children may need less than 15 grams of carbs, especially infants and toddlers.”
• ADA Standards of Care 2026, section 6: “Glucose is the preferred treatment for the conscious individual with glucose <70 mg/dL (<3.9 mmol/L), although any form of carbohydrate that contains glucose may be used.”

Every quote above is checked against its source page before each update of this site; last checked 2026-10-06. The worked example is our own arithmetic. This page explains a term; it is not advice for a person's treatment.