You know that sluggish, "brain fog" feeling after a massive Thanksgiving dinner? Most of us just call it a food coma and move on with our lives. But sometimes, that heavy, lethargic sensation isn't just about the turkey. It's your biology screaming at you. When we talk about 5 signs your blood sugar is too high, we aren't just checking off boxes on a medical form. We're looking at how your body struggles to process fuel.
Hyperglycemia is sneaky. It doesn't always feel like a sudden medical emergency. Often, it feels like getting older, or being stressed, or just "having a rough week." But if your glucose stays elevated, your blood basically turns into syrup. It's thick. It's sticky. It damages the tiny vessels in your eyes and kidneys. According to the Centers for Disease Control and Prevention (CDC), roughly 38 million Americans have diabetes, and a staggering 1 in 5 don't even know it. That’s because the symptoms are masters of disguise.
Let's get into the weeds of what’s actually happening inside your veins.
That unquenchable thirst that makes no sense
You drank a liter of water. Ten minutes later, your mouth feels like it’s full of cotton balls. This isn't normal thirst. In the medical world, they call this polydipsia.
Here is the deal: when your blood sugar is high, your kidneys go into overdrive. They're trying to filter out all that excess glucose. But glucose is a bit of a space hog; it pulls water along with it. This leads to a vicious cycle. You pee more because your kidneys are flushing the sugar, and because you're peeing more, you get dehydrated.
I’ve talked to people who describe it as a "deep thirst" that water can't seem to touch. You might find yourself reaching for a soda or juice because you're desperate for moisture, but that just dumps more fuel onto the fire. If you’re waking up three times a night to hit the bathroom (nocturia), it’s rarely just because you had tea before bed. It’s a classic red flag.
Why you’re exhausted even after eight hours of sleep
It seems counterintuitive, right? Sugar is energy. If you have tons of sugar in your blood, you should be bouncing off the walls. But the body doesn't work like that.
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Think of your cells like a car and glucose like the gasoline. In a healthy body, insulin acts as the key that opens the gas tank. When you have high blood sugar, either the key is broken or the lock is jammed. The gasoline is just sloshing around in the trunk (your bloodstream) instead of getting into the engine.
The result? You’re starving for energy at a cellular level. You feel heavy. Procrastination becomes your default state because the physical effort of moving feels like walking through waist-deep mud. This isn't just "tired." It’s a profound, systemic fatigue that a double espresso won't fix. The American Diabetes Association often notes that fatigue is one of the most underreported symptoms because people just blame their busy schedules.
Your vision is suddenly "glitchy"
This one is actually terrifying when it first happens. You’re reading a text or looking at a street sign, and things look... blurry. Not "I need a new prescription" blurry, but more like you’re looking through a foggy window.
High blood glucose causes the lenses in your eyes to swell.
Literally. The excess sugar changes the fluid levels in your eye tissues, which alters the shape of the lens. This changes your focus. The good news is that this is usually temporary. Once your blood sugar levels stabilize, the swelling goes down and your vision typically returns to whatever your "normal" is. However, if you ignore this, long-term high sugar leads to diabetic retinopathy, where the blood vessels in the back of the eye actually leak or grow abnormally. That part isn't temporary.
Wounds that just won't heal
Keep an eye on that papercut. Or the blister from your new shoes. Normally, your body is a healing machine. A small scrape should be a memory within a few days.
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But when your blood sugar is high, your circulation takes a massive hit. High glucose levels make the blood vessels narrow and lose their elasticity. This slows down blood flow, especially to your extremities like your feet and hands. Without proper blood flow, the "repair crew"—your white blood cells—can't get to the site of the injury.
Furthermore, bacteria love sugar. If you have a high concentration of glucose in your tissues, you’re basically providing an all-you-can-eat buffet for infections. What should have been a minor scratch becomes an angry, red, lingering sore. This is why podiatrists are often the first ones to diagnose diabetes; they see the evidence on the feet before the patient even feels sick.
The weird "skin tags" and darkened patches
Most people think of blood sugar as an internal problem, but it shows up on your skin loud and clear. Have you noticed patches of skin that look a bit dirty or velvety, particularly around the neck, armpits, or groin?
This is called Acanthosis nigricans.
It’s often a sign of insulin resistance. Essentially, high levels of insulin in the blood cause skin cells to reproduce faster than normal. These new cells have more melanin, which results in those dark, thickened patches. You might also notice a sudden explosion of skin tags. While skin tags can happen to anyone, a sudden increase is a common signal that your body is struggling to manage its insulin levels. It’s your skin acting as a billboard for your internal chemistry.
Beyond the "Big Five": The subtle shifts
We’ve covered the primary 5 signs your blood sugar is too high, but the body is complex. You might also experience:
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- Unexplained weight loss: Wait, didn't I say sugar is fuel? If your body can't use glucose, it starts burning fat and muscle for energy. You might lose weight even while eating more than usual. This is especially common in Type 1 diabetes but can happen in advanced Type 2.
- Frequent yeast infections: Like I said, yeast and bacteria thrive on sugar. If your system is sugar-rich, you’re more prone to these issues.
- Tingling in the hands or feet: This is peripheral neuropathy. That "pins and needles" feeling is actually your nerves being damaged by the toxic effects of high glucose.
What should you actually do?
Honestly, don't panic, but don't ignore it either. The human body is remarkably resilient if you catch things early. If you recognize these signs, your first stop shouldn't be a fad diet or a "sugar detox" kit from an Instagram ad. It needs to be a lab test.
Ask your doctor for an A1C test.
Unlike a finger-prick test that just tells you what your sugar is right now, the A1C gives you an average of your blood sugar over the last two to three months. It’s the "cheating proof" test. It tells the real story of how your body is handling its fuel.
Immediate Actionable Steps
- Hydrate with water only: If you're thirsty, drink plain water or seltzer. Avoid the "healthy" smoothies or sports drinks that are often packed with hidden sugars.
- Move for 15 minutes after eating: You don't need a CrossFit session. A brisk walk after a meal helps your muscles soak up that excess glucose without needing as much insulin.
- Audit your "hidden" carbs: It's not just the candy bars. White bread, pasta, and even "low-fat" yogurts are often sugar bombs in disguise.
- Monitor your sleep: Poor sleep increases cortisol, which in turn spikes blood sugar. It’s a nasty cycle that needs to be broken.
- Get a glucose monitor: You can buy a basic over-the-counter glucometer for about $20. Testing yourself a few mornings in a row (fasting) can give you a baseline of data to bring to your doctor.
Blood sugar management isn't about being perfect. It's about awareness. If you feel "off," trust your gut. Your body doesn't develop these symptoms for no reason; it's a communication system. Listen to it before the whisper turns into a shout.
Next Steps for Your Health:
Book an appointment for a metabolic panel and A1C test. Start a simple food diary for three days—noting not just what you eat, but how you feel two hours afterward. This data is the most powerful tool you have for a conversation with your healthcare provider.