You know that feeling after a massive Thanksgiving dinner where you just want to curl up on the rug and disappear for three hours? That "food coma" is a common enough joke. But when that heavy, foggy, bone-tired exhaustion starts happening after a regular turkey sandwich—or worse, when you haven’t even eaten yet—something else is likely going on. High blood sugar isn't always a dramatic, "clutching your chest" kind of event. It’s sneakier. It’s quiet. Honestly, hyperglycemia signs and symptoms often feel like just "having a rough week" until they don't.
High blood sugar, or hyperglycemia, basically means there is too much glucose hitching a ride in your bloodstream because your body can’t effectively move it into your cells for energy. If you have diabetes, you’re already familiar with this struggle. But for those in the pre-diabetic range or those dealing with undiagnosed issues, these signs are easy to brush off. You're thirsty because it's dry out. You're tired because work is stressful. You’re peeing more because you drank an extra latte.
The reality is more complex.
The Physiological "Why" Behind the Thirst
Excess sugar in the blood acts like a sponge. It’s osmotic. When your glucose levels cross a certain threshold—usually around 180 mg/dL—your kidneys can’t keep up. They start dumping the extra sugar into your urine. Because sugar carries water with it, you end up peeing way more than usual. This is called polyuria.
It’s a cycle. You pee more, you get dehydrated, your brain screams for water (polydipsia), and you drink more. Then you pee again.
I’ve talked to people who thought they were just being "extra healthy" by hitting their gallon-of-water-a-day goal, only to realize they were drinking that much because their body was desperately trying to flush out a glucose surplus. It isn't just "thirst." It’s a parched, dry-mouth feeling that doesn't go away even after a glass of ice water.
Blurred Vision and the "Sugar Lens"
This is one of the weirdest symptoms. High blood sugar can actually change the shape of the lens in your eye. When glucose levels are high, water is pulled into the lens, causing it to swell. Suddenly, your prescription feels "off." You might find yourself squinting at the TV or struggling to read the fine print on a menu.
The good news? It’s usually temporary. Once your blood sugar stabilizes, your vision typically clears up. But if you find yourself constantly rubbing your eyes or wondering why the world looks a bit hazy, it’s a massive red flag.
The Fatigue That Sleep Won't Fix
We aren't talking about being "sleepy." This is a deep, cellular lethargy. Think about it: glucose is your body's primary fuel. If that fuel is stuck in your bloodstream instead of getting into your muscles and brain, you’re essentially starving on a cellular level despite having plenty of "gas" in the tank.
It's a cruel irony. Your blood is thick with energy, yet you feel like you're walking through wet cement.
Dr. Anne Peters, a renowned endocrinologist at Keck Medicine of USC, often points out that this fatigue can affect cognitive function. People describe it as "brain fog." You forget where you put your keys. You stare at an email for ten minutes because you can’t find the right words. It’s your brain struggling to function without its preferred energy source being delivered correctly.
👉 See also: How to Get Sick Quickly: The Science of Why Your Body Cracks Under Pressure
Unintentional Weight Loss: The Red Flag
If you’re eating like a horse but the scale is moving down, don't celebrate just yet. When your body can't use glucose for energy, it starts burning fat and muscle for fuel instead. This is particularly common in Type 1 diabetes but can happen in severe cases of Type 2 hyperglycemia.
- You might notice your clothes fitting looser.
- Your muscles might feel weaker or "thinner."
- There's often a persistent hunger (polyphagia) because your cells are sending out "I'm starving" signals.
Why Your Skin and Healing Matter
Ever noticed a small scratch that just... lingers? Maybe a paper cut that stays red and angry for two weeks?
High blood sugar wreaks havoc on your circulatory system. It damages the tiny blood vessels and slows down the delivery of white blood cells to the site of an injury. It also provides a literal feast for bacteria and yeast. This is why people with chronic hyperglycemia often deal with:
- Frequent yeast infections (yeast loves sugar).
- Slow-healing sores on the feet or legs.
- Itchy, dry skin that feels "tight" regardless of how much lotion you use.
- Dark, velvety patches of skin—usually around the neck or armpits—known as acanthosis nigricans. This is a classic sign of insulin resistance.
The Danger Zone: DKA and HHS
Sometimes, hyperglycemia moves beyond "annoying" and into "life-threatening." If blood sugar stays too high for too long, or spikes aggressively, you hit the danger zone.
Diabetic Ketoacidosis (DKA) is the big one. This happens when the body starts breaking down fats at a rate that is too fast for the body to handle, creating ketones. Ketones make your blood acidic. It’s a medical emergency.
You’ll know it’s DKA if the hyperglycemia signs and symptoms shift into:
- Fruit-scented breath (it smells like Juicy Fruit gum or nail polish remover).
- Nausea and vomiting.
- Shortness of breath (Kussmaul breathing).
- Extreme confusion.
There's also Hyperosmolar Hyperglycemic State (HHS), which is more common in older adults with Type 2. The blood sugar levels here can go astronomical—sometimes over 600 mg/dL. It causes severe dehydration and can lead to a coma.
Real-World Nuance: It’s Not Just About Sweets
A common misconception is that you only get high blood sugar if you eat a bag of jellybeans.
Not true.
Stress is a massive trigger. When you're stressed, your body releases cortisol and adrenaline. These hormones tell your liver to dump stored glucose into the blood to give you the "fight or flight" energy you need. If you're a diabetic or insulin resistant, that sugar has nowhere to go. You could eat a salad and still have high blood sugar if you’re under immense pressure at work or dealing with an infection.
Illness is another one. Even a simple cold can cause your blood sugar to skyrocket. Your body is fighting an internal war, and it needs extra energy to do it, which results in more circulating glucose.
What to Do Right Now
If you recognize these signs, don't panic, but don't ignore them either.
First, get data. You can't manage what you don't measure. If you have a glucose monitor, use it. If you don't, it’s time for a trip to the doctor for an A1C test. This test gives you a three-month average of your blood sugar levels, which is much more telling than a single "snapshot" finger prick.
Hydrate, but be smart. Drink water. Avoid the "sugar-free" sodas or juices for a moment; just stick to plain water to help your kidneys flush out the excess.
Move—if it's safe. If your blood sugar is moderately high (say, 200 mg/dL), a 20-minute walk can help your muscles soak up that excess glucose. However, if your sugar is very high (over 240 mg/dL), check for ketones first. Exercising with high ketones can actually drive your blood sugar higher and trigger DKA.
Review your meds. If you’re already on insulin or Metformin, check your dosages. Did you miss a pill? Was your insulin exposed to heat? Sometimes the "symptom" is actually just a failure of the delivery system.
Actionable Steps for Management
- The 15-Minute Walk: Make it a habit to walk for 15 minutes immediately after your largest meal. This utilizes the "glucose transporters" in your muscles to pull sugar out of the blood without needing as much insulin.
- Fiber First: When eating, try to eat your fiber (veggies) and protein before your carbohydrates. This slows down the absorption of sugar into the bloodstream, preventing the "spike and crash" cycle.
- Sleep Hygiene: Chronic sleep deprivation makes your cells more resistant to insulin. Aim for 7-8 hours to keep your hormones balanced.
- Audit Your Stress: If you notice your levels are high during the work week but normal on weekends, your job is literally raising your blood sugar. Breathwork or "box breathing" can actually lower your cortisol and, by extension, your glucose.
Hyperglycemia isn't a moral failing; it's a physiological signal. Your body is a complex machine trying to tell you that the fuel system is clogged. Pay attention to the thirst, the fog, and the fatigue. They are the only way your body knows how to ask for help.
Next Steps:
- Schedule a fasting glucose or A1C test with your primary care provider.
- Keep a 3-day log of what you eat and how you feel two hours later.
- Increase daily water intake by 24 ounces to support kidney filtration.
- Monitor any skin changes or slow-healing wounds specifically on the lower extremities.