Hypoglycemia: How to Recognize, Treat, and Prevent Low Blood Sugar

When your blood sugar drops too low, your body doesn’t just feel off-it can start to shut down. You might shake, sweat, or feel confused. In severe cases, you could pass out or have a seizure. This isn’t just a scare-it’s hypoglycemia, and it’s one of the most common and dangerous complications of diabetes treatment. Around 47% of people with Type 1 diabetes and 33% of those on insulin for Type 2 diabetes experience it at least once a year. The good news? Most episodes are preventable-and treatable-if you know what to look for and what to do.

What Counts as Low Blood Sugar?

Hypoglycemia is defined as a blood glucose level below 70 mg/dL (3.9 mmol/L) for people with diabetes. The NHS in the UK uses a slightly higher threshold of 4 mmol/L (72 mg/dL) to trigger treatment. For someone without diabetes, low blood sugar is considered below 55 mg/dL (3.1 mmol/L). But numbers alone don’t tell the whole story. Some people feel symptoms at 70 mg/dL, while others don’t notice anything until it’s below 50 mg/dL. That’s because your body adapts-and sometimes, it forgets to warn you.

How Do You Know You’re Having a Low?

Symptoms fall into two categories: physical (adrenergic) and mental (neuroglycopenic). The first group comes from your body’s stress response. You might feel your heart racing, your hands trembling, or sweat pouring out-even if the room is cold. These are signs your body is releasing adrenaline to try and raise your blood sugar.

The second group is more dangerous. That’s when your brain doesn’t get enough glucose. You might get blurry vision, feel dizzy, or struggle to speak clearly. At 50 mg/dL or lower, confusion sets in. Below 45 mg/dL, you can lose consciousness. Seizures can happen if it drops even further. This is why hypoglycemia is often mistaken for intoxication or a stroke-especially in public.

People with long-term diabetes often lose these warning signs. About 25% of Type 1 patients develop hypoglycemia unawareness after 15+ years. They don’t shake or sweat anymore. Their first symptom? Passing out. That’s why continuous glucose monitors (CGMs) are so critical-they give you data before your body does.

What Causes Low Blood Sugar?

For people with diabetes, three things cause most episodes:

• Too much insulin (73% of cases): Taking your usual dose but eating less, or injecting too much by mistake.
• Not enough carbs (19%): Skipping meals, eating smaller portions, or not adjusting for activity.
• Unexpected exercise (9%): A walk, a workout, or even cleaning the house can drop glucose fast if insulin isn’t lowered.

Non-diabetics can get hypoglycemia too, but it’s rare. Reactive hypoglycemia happens after meals-often after gastric bypass surgery. Fasting hypoglycemia can signal serious issues like insulinomas (tumors that make too much insulin) or liver/kidney failure.

What to Do When Blood Sugar Drops

If you’re alert and able to swallow, follow the 15-15 rule:

1. Consume 15 grams of fast-acting carbs: 4 glucose tablets, 1/2 cup of juice, 1 tablespoon of honey, or 6 hard candies.
2. Wait 15 minutes.
3. Check your blood sugar again.

If it’s still below 70 mg/dL, repeat. Once it’s back up, eat a snack with protein and complex carbs-like peanut butter on toast-to prevent another drop.

But what if you can’t swallow? That’s when the 15-15 rule fails. If someone is confused, unconscious, or having a seizure, do not give them food or drink. You could choke them. Instead, use glucagon.

Glucagon is a hormone that tells the liver to release stored sugar. It comes as an injection or nasal spray. A 1 mg intramuscular shot works in under 15 minutes for 85% of cases. Nasal glucagon is easier to use but slightly less effective. Every person with diabetes on insulin should have glucagon available-and their family, coworkers, or friends should know how to use it. Training takes less than 10 minutes.

Preventing Low Blood Sugar

Prevention is better than treatment. Here’s how to cut your risk:

• Match carbs to insulin: If you take 1 unit of insulin for every 10-15 grams of carbs, stick to that ratio. Don’t guess.
• Adjust for activity: If you’re going to exercise for more than 45 minutes, reduce your basal insulin by 20-50% or eat extra carbs before and during.
• Use a CGM: Devices like Dexcom or Freestyle Libre show real-time trends. Set alerts at 70 mg/dL and 55 mg/dL. Some systems, like the Guardian 4 or Tandem Control-IQ, can automatically pause insulin delivery if your glucose is dropping too fast.
• Check before bed: Nighttime lows are the most dangerous. Aim for a bedtime glucose above 80 mg/dL. If it’s below 100 mg/dL, eat a small snack with protein and fat-like cheese or nuts.
• Wear medical ID: A bracelet or necklace that says “Diabetic-Insulin Dependent” can save your life if you’re found unconscious.

Technology Is Changing the Game

In 2023, the FDA approved Dasiglucagon (Zegalogue), a nasal powder that works faster and more reliably than older glucagon injections. The first closed-loop “artificial pancreas” systems, like Tandem Control-IQ, now reduce time spent below 54 mg/dL by over 3 hours per week.

CGM adoption has jumped from 12% in 2017 to 67% in 2023 among insulin users. That’s led to a 29% drop in hospital visits for hypoglycemia. But tech isn’t perfect. Sensor lag can miss rapid drops-some users report readings 40 mg/dL higher than actual blood sugar during fast declines. Always confirm with a fingerstick if you feel symptoms but the CGM says you’re fine.

Who’s at Highest Risk?

- Type 1 diabetes: Average of 19 episodes per month. Most are mild, but the risk of severe lows is highest.

- Elderly patients (>65): Often show atypical symptoms-falls, confusion, dizziness-mistaken for dementia. Each severe episode raises dementia risk by 4.7%.

- People with hypoglycemia unawareness: 6-fold higher risk of death.

- Those on multiple daily injections or pumps: More insulin flexibility means more room for error.

What Not to Do

- Don’t ignore mild symptoms. A 65 mg/dL reading might seem “fine,” but cognitive impairment starts here. Driving at 50 mg/dL is like driving with a 0.08% blood alcohol level.

- Don’t over-treat. Eating a whole bag of candy to fix a 60 mg/dL low can send your sugar soaring, leading to rebound highs.

- Don’t assume your symptoms are the same every time. Studies show 37% of people experience different signs from one episode to the next.

- Don’t wait to train others. If you live alone, teach a neighbor or friend how to use glucagon. Keep a written instruction sheet in your wallet.

When to Call for Help

Call 999 or go to A&E if:

• You or someone else is unconscious or having a seizure.
• Glucagon was given but there’s no improvement after 15 minutes.
• You’ve had two or more severe lows in one week.
• You’re unsure whether it’s hypoglycemia or something else-many ER visits are misdiagnosed as strokes.

Final Thoughts

Hypoglycemia isn’t a failure-it’s a signal. It tells you your treatment plan needs tweaking. With the right tools-CGMs, glucagon, carb counting, and education-you can live without fear of low blood sugar. The goal isn’t perfection. It’s awareness. It’s preparation. It’s knowing what to do before your body screams for help.