How to Raise a Low Blood Sugar Quickly and Safely: A Carb-Based Guide

If you use insulin, you know that low blood sugar (hypoglycemia) can happen suddenly, and when it does, every second counts. Using carbohydrates correctly can help you raise a low blood sugar quickly and safely. This article covers two essential methods, or “guides,” that allow you to calculate how much carbohydrate you need and choose the right kind.

These rules can also help you match your meal carbs with insulin for better post-meal readings—but more importantly, they are your tools to recover from a low and prevent a dangerous drop in glucose.

Guide 1: How Many Points Does 1 Gram of Carbohydrate Raise Blood Sugar?

The amount of carbohydrate needed to raise blood sugar depends largely on your body weight. As a general rule:

• 1 gram of carbohydrate raises blood sugar by:

  • ~5 mg/dL if you weigh 100 lbs

  • ~4 mg/dL if you weigh 150 lbs

  • ~3 mg/dL if you weigh 200 lbs

Example:

Let’s say you weigh 150 lbs and your current blood glucose is 60 mg/dL. You want to raise it to at least 100 mg/dL before your next meal.

That’s a 40-point increase.

• At 4 points per gram (for 150 lbs), you need:

  • 40 ÷ 4 = 10 grams of carbohydrate

This could be two glucose tablets (each with 5 grams of fast-acting carbohydrate), which are ideal for rapid correction.

Guide 2: The Type of Carb Matters—Glycemic Index and Speed of Action

The type of carbohydrate you use to treat a low is just as important as the amount you use. Foods vary in how quickly they are digested and absorbed, based on their glycemic index (GI).

• Fast-acting carbs (high GI) like glucose tablets, juice, or regular soda work within 10–15 minutes.

• Slow carbs (low GI) like beans, whole grains, or dairy digest more slowly and can take 1–3 hours to raise blood sugar.

Example:

You’re low and want to eat 15 grams of carbohydrate.

• If you choose glucose tablets (GI = 100), your blood sugar should rise quickly.

• If you eat kidney beans (GI = 33) instead, your blood sugar might not rise for hours, and could even drop further before it improves.

Bottom line: Use high-GI foods for treating lows. Save low-GI foods for regular meals.

Best Fast-Acting Carbs to Raise a Low Blood Sugar

According to the American Diabetes Association (ADA) and leading clinical trials on hypoglycemia treatment, here are some trusted fast-acting carbs:

Always follow up with a longer-lasting snack if your next meal is more than 30–60 minutes away.

When to Retest and Treat Again

After treating a low, check your blood sugar again in 15 minutes. If it’s still below 70 mg/dL, treat again with another 15 grams of fast-acting carbohydrate.

This is known as the “15-15 Rule”:

• Eat 15 grams of carbohydrate

• Wait 15 minutes, then retest

Repeat until your blood sugar is safely above 70 mg/dL.

Preventing Future Lows

While treating lows quickly is important, preventing them is even better. Talk to your diabetes care team about:

• Adjusting insulin doses after exercise

• Matching insulin to food intake more precisely

• Reducing long-acting insulin if nighttime lows occur

• Using continuous glucose monitoring (CGM) with low alerts

Final Thoughts

Knowing how to raise low blood sugar is a critical skill for anyone using insulin. These two guides—how much carb to take and which kind to use—can help you act fast, stay safe, and keep your blood sugar in target range.

Use fast-acting carbs when you’re low, and always follow up with a retest. With the right knowledge, you can manage hypoglycemia confidently and prevent serious complications.