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Raise Low Blood Glucose Fast: The 15-15 Rule

Reviewed 2026-10-25 · How we write

Illustration of orange juice, glucose tablets, honey and candies next to a kitchen timer

A blood sugar below 70 mg/dL (3.9 mmol/L) needs fast action. The proven method is the 15-15 rule: 15–20 g of fast-acting carbohydrate, then re-check after 15 minutes.

Signs of low blood glucose

Shakiness, sweating, a racing heart, hunger, anxiety, tingling lips, pallor; then difficulty concentrating, blurred vision, irritability and confusion. When in doubt and you can't test: treat.

The 15-15 rule step by step

  1. Eat or drink 15–20 g of fast-acting carbohydrate.
  2. Wait 15 minutes — glucose needs time to rise. Eating more in the meantime often leads to a high later.
  3. Re-check. Still below 70 mg/dL? Take another 15–20 g.
  4. Once above 70 mg/dL, eat a snack with carbohydrate and protein (for example crackers with cheese) if your next meal is more than an hour away.

For level 2 lows (below 54 mg/dL), many care teams recommend the upper end, 20 g.

What 15–20 g of fast-acting carbohydrate looks like

SourceAmount for about 15 g
Glucose tablets (4 g each)4 tablets
Glucose gel1 tube (check the label)
Fruit juice½ cup (4 oz / 120 ml)
Regular (not diet) soda½ cup (4 oz / 120 ml)
Table sugar or honey1 tablespoon
Hard candies or jelly beanscheck the label — usually 4–8 pieces

Avoid chocolate, cookies and other fatty foods for treating lows — fat slows absorption. If you take acarbose, use glucose tablets or gel: table sugar works poorly with it.

When the person cannot help themselves

If someone is confused, cannot swallow safely or is unconscious: do not put food or drink in their mouth. Give glucagon (nasal spray or injection) if available, turn them into the recovery position and call 911 (US) or your local emergency number. Once they wake and can swallow, give fast sugar and then a snack.

After a low

  • Don't drive until you are back above 70 mg/dL and feel normal — and ideally wait 30–45 minutes.
  • Think about the cause: dose, meal, exercise, alcohol?
  • Tell your care team if lows happen more than once or twice a week, or at night.

More: Low Blood Sugar (Hypoglycemia): Levels & Treatment · diabetes first aid

Sources: ADA: Hypoglycemia · NIDDK: Low blood glucose · MedlinePlus: Low blood sugar self-care

Check a blood glucose reading

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Educational content only; not medical advice. Follow the treatment plan you have agreed with your doctor or diabetes team. In an emergency, call 911 (US) or your local emergency number.