The 15-15 Rule: Your Go-To Protocol

When your blood sugar drops below 70 mg/dL (3.9 mmol/L), you need a simple, reliable plan. That plan is the 15-15 rule, and it has been the gold standard recommended by the ADA for decades. Here is how it works:

1. Eat or drink 15 grams of fast-acting carbohydrates
2. Wait 15 minutes
3. Recheck your blood sugar
4. If still below 70 mg/dL, repeat

That is it. Four steps. Simple enough to follow even when your brain is foggy from a low. The beauty of this protocol is its simplicity — when you are shaking, sweating, and struggling to think clearly, you do not want a complicated decision tree. You want automatic pilot.

Why Exactly 15 Grams?

This is not an arbitrary number. Research shows that 15 grams of fast-acting carbohydrates typically raises blood sugar by approximately 30-45 mg/dL (1.7-2.5 mmol/L) within 15-20 minutes. That is usually enough to bring you from a Level 1 hypo (54-69 mg/dL) back into a safe range without overshooting into hyperglycemia.

Think of it like a precision tool: enough to fix the problem, not so much that you create a new one. Too little, and you stay dangerously low. Too much, and you end up on a blood sugar roller coaster — crashing low, then spiking high, then possibly crashing again.

Fast-Acting Carbohydrate Options

Not all carbs are created equal when it comes to treating hypos. You need carbs that hit your bloodstream fast — pure glucose or fast-acting carbs with minimal fat, protein, or fiber to slow absorption.

15g Fast-Acting Carbs Quick Reference

What NOT to Use

This is just as important. These foods contain fat, protein, or fiber that significantly slows glucose absorption:

• Chocolate — fat slows absorption dramatically (can take 30+ minutes)
• Ice cream — same problem, high fat content delays the sugar
• Cookies or pastries — fat + complex carbs = slow response
• Diet or sugar-free drinks — contain zero fast-acting carbs
• Protein bars — designed to release energy slowly, the opposite of what you need
• Milk — lactose is slower than glucose, and fat slows it further
• Fruit with skin — fiber slows absorption (banana is OK, apple with skin is slower)

AID Systems: A Modified Approach

If you use an Automated Insulin Delivery (AID) system — also called a closed-loop or hybrid closed-loop pump — your system is already working to prevent and correct lows by reducing or suspending basal insulin delivery. Because of this, you may not always need the full 15 grams.

For mild lows (60-69 mg/dL) with an AID system:

• 5-10 grams of fast-acting carbs may be sufficient
• Your pump has likely already reduced or suspended insulin
• Watch your CGM trend arrows — if the arrow is pointing up or flat after treatment, your system is doing its job

For Level 2 lows (below 54 mg/dL), treat with the full 15g regardless of your pump system. Safety first.

Scenario: Alex's First Hypo Treatment

Alex was diagnosed with T1D three months ago. During a study session at the library, they start feeling shaky and notice their hands trembling while turning pages. Their CGM buzzes: 63 mg/dL, trending down.

Here is how Alex handles it using the 15-15 rule:

Step 1 — Alex reaches into their backpack where they always keep a tube of glucose tablets. They eat 4 tablets (16g of fast-acting carbs — close enough to 15g).

Step 2 — Alex sets a 15-minute timer on their phone. They close their textbook because concentrating is impossible right now anyway. They sit still and wait.

Step 3 — The timer goes off. Alex checks their CGM: 89 mg/dL, trending up. Success! The low is resolving.

Step 4 — Since they are above 70 mg/dL and trending up, no repeat treatment is needed. Alex has a small snack (a few crackers with peanut butter) since dinner is still two hours away, then goes back to studying.

No panic. No raid on the vending machine. Just a calm, methodical response that fixed the problem in 15 minutes.