When your blood sugar climbs too high, your body doesn’t just feel off-it starts shutting down. You might think it’s just fatigue, thirst, or a bad day. But if your glucose is above 250 mg/dL and you’re ignoring the signs, you could be one step away from a life-threatening emergency. Hyperglycemia isn’t just a number on a meter. It’s a warning signal your body is screaming for help.

What High Blood Sugar Actually Feels Like

Most people don’t notice high blood sugar until it’s already severe. Early symptoms are easy to brush off. You’re drinking more water than usual-not because it’s hot, but because your kidneys are trying to flush out excess sugar. You’re peeing every hour, even at night. Your mouth feels dry, no matter how much you drink. That’s polyuria and polydipsia-classic signs of blood sugar above 180 mg/dL.

Then comes the brain fog. You can’t focus at work. You forget where you put your keys. You feel sluggish, even after sleeping. That’s not laziness. That’s your brain starving for fuel. Glucose is flooding your bloodstream, but without enough insulin, your cells can’t use it. So your body starts breaking down fat for energy, which leads to another red flag: unexplained weight loss. You’re eating normally, but dropping pounds. That’s a major red flag, especially if you have type 2 diabetes.

Blurred vision? That’s not just eye strain. High glucose swells the lens of your eye, warping your focus. It’s temporary-but if ignored, it can become permanent. Studies show 68% of people with uncontrolled diabetes report this symptom before seeking help. By then, it’s often too late for simple fixes.

When It Turns Dangerous: DKA and HHS

If your blood sugar hits 250 mg/dL or higher, you’re in danger zone. Two emergencies can follow: diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). They’re both deadly, but they look and act differently.

DKA mostly hits people with type 1 diabetes. Your body, starved of insulin, starts burning fat like crazy. That creates toxic acids called ketones. You’ll smell them-sweet, fruity breath, like nail polish remover. You’ll start breathing fast and deep, trying to blow off the acid. That’s Kussmaul breathing. You might feel nauseous, have stomach pain, or even vomit. Blood pH drops below 7.3. This isn’t just bad-it’s an ICU-level emergency. DKA kills 2-5% of adults who don’t get treated fast.

HHS is worse. It mostly affects older adults with type 2 diabetes. Blood sugar soars past 600 mg/dL. Your body loses so much fluid through urine that you become severely dehydrated. You might not even feel thirsty anymore. Your skin is dry. Your heart races. You get confused, dizzy, or even start having seizures. Unlike DKA, there are few ketones-just extreme dehydration and brain dysfunction. HHS kills 15-20% of people who reach this stage. For those over 65, the death rate jumps to 22%.

The difference? DKA comes on fast-within hours. HHS creeps in over days. You might think you’re just “getting older” or “coming down with something.” But if your blood sugar is over 500 mg/dL and you’re not yourself, you’re in a medical crisis.

What to Do Right Now

If your blood sugar is above 240 mg/dL, don’t wait. Don’t hope it’ll go down on its own. Act immediately.

• Test for ketones. Use a urine strip or a blood ketone meter. If ketones are moderate or high, you’re at risk for DKA.
• Take your fast-acting insulin. Most people need 0.1 units per kilogram of body weight every hour until levels drop. Never skip this step.
• Drink water-no sugar, no soda. Aim for 8-16 ounces every hour. Dehydration makes everything worse.
• Don’t exercise. Working out when ketones are present can push your sugar even higher.
• Call your doctor or go to the ER if your blood sugar stays above 300 mg/dL after two hours of insulin and fluids, or if you feel confused, nauseous, or have trouble breathing.

Many people delay care because they’re scared of hospitals or think they can handle it. But 41% of emergency cases reported by diabetes patients were caused by waiting too long. Time is critical. Every hour counts.

Why This Keeps Happening

You’re not failing. This isn’t about willpower. Hyperglycemia happens because of real, biological problems.

The “dawn phenomenon” is a silent culprit. Between 4 and 8 a.m., your body releases stress hormones like cortisol and growth hormone. These naturally raise blood sugar to wake you up. But if you have diabetes, your body can’t counter it with enough insulin. That’s why many people wake up with sugar over 200 mg/dL-even if they ate nothing the night before.

Insulin pump failures? They’re more common than you think. A clogged catheter, a disconnected tube, or a dead battery can send your sugar soaring in hours. One in five hyperglycemia emergencies in pump users is due to device issues.

Illness is another big trigger. A cold, the flu, even a UTI can spike your blood sugar. Your body releases stress hormones to fight infection-and those hormones block insulin. You might need 20-50% more insulin during sickness. Most people don’t adjust.

And then there’s insulin stacking. Taking extra insulin too soon because your sugar didn’t drop fast enough? That’s a recipe for a dangerous crash later. It’s the #1 mistake in pump users.

How to Stop the Cycle

The good news? You can break this pattern.

Continuous glucose monitors (CGMs) are the biggest game-changer. They don’t just tell you your sugar is high-they warn you it’s about to be. Dexcom’s G7, approved in early 2024, predicts high blood sugar 30 minutes in advance. Users report 31% fewer severe episodes.

Education works. People who complete CDC-certified diabetes self-management programs cut their emergency visits by 42%. They learn how to adjust insulin for illness, how to read ketone strips, how to hydrate properly.

Check your blood sugar every 4 hours when you’re sick or stressed. Don’t rely on how you feel. Feelings lie. Numbers don’t.

Talk to your doctor about basal insulin adjustments if you’re consistently high in the morning. A 20-30% increase in your overnight basal rate can fix dawn phenomenon without extra shots.

And if you’re struggling with access to insulin or CGMs-know you’re not alone. Black patients are 2.3 times more likely to have hyperglycemia emergencies because of cost and care barriers. Ask about patient assistance programs. Medicare now covers CGMs for most people with diabetes. Don’t let price stop you from staying safe.

What Comes After the Emergency

Surviving a hyperglycemic crisis doesn’t mean you’re safe. Recovery takes weeks. Your body is damaged. Your kidneys, nerves, and blood vessels have been under extreme stress.

Follow up with your endocrinologist. Get an A1C test. Review your insulin dosing. Check for gastroparesis-a condition where your stomach empties slowly, causing delayed insulin absorption. It’s behind nearly 19% of recurrent high blood sugar cases.

Start tracking triggers. Use a simple log: time, sugar level, food, insulin, stress, illness. Patterns will emerge. You’ll start to see that every time you skip a meal, your sugar spikes. Or that your anxiety at work sends your numbers up.

The goal isn’t perfection. It’s awareness. It’s catching it early. It’s knowing that a sugar of 260 mg/dL isn’t “just a little high”-it’s a signal that your system is breaking down.

Real People, Real Stories

One man, 68, thought his confusion and dizziness were just aging. His sugar was 720 mg/dL. He was in a coma for three days. He survived, but lost kidney function.

A teenager with type 1 diabetes skipped her insulin for a weekend party. Her ketones hit 5.2 mmol/L. She was rushed to the ER. She’s fine now-but she wears her CGM 24/7 and never misses a dose again.

A woman in Ohio used her CGM’s alert to take insulin before her sugar hit 300. She avoided DKA. She says, “That beep saved my life. I used to think I was fine until I felt awful. Now I act before I feel anything.”

You don’t need to wait until you’re sick to act. You don’t need to be perfect. You just need to know the signs-and act before it’s too late.