Warning: Hyperglycemia Symptoms You Should Never Ignore

Meera thought she just needed more water. Her mouth felt like sandpaper, and she was running to the bathroom every hour. "Must be the heat," she told herself. Three days later, she was in the emergency room with a blood sugar of 487 mg/dL and a diagnosis that would change her life forever.

What Meera didn't know—and what most people with hyperglycemia don't realize—is that her body had been sending warning signals for weeks. Signals she could have recognized if she'd known what to look for.

Hyperglycemia (high blood sugar) affects over 237 million people in India with diabetes or prediabetes. But here's what makes this condition so dangerous: by the time most people feel "sick enough" to seek help, their blood sugar has often reached crisis levels.

In this guide, you'll learn exactly what those early warning signs look like—and discover one counterintuitive symptom that catches even experienced diabetics off guard. (Hint: it involves something you do every night.)

📖 What is Hyperglycemia?

Hyperglycemia (pronounced: HY-per-gly-SEE-mee-uh) is the medical term for high blood sugar. It occurs when glucose builds up in the bloodstream because the body either doesn't produce enough insulin or can't use insulin effectively. The prefix "hyper" means "too much" and "glycemia" refers to glucose in the blood.

📊 Track Your Time Above Range — My Health Gheware calculates your Time in Range and Time Above Range automatically from CGM data, helping you identify hyperglycemia patterns. Try it free →

💡 Key Insight: The landmark ADAG study that established HbA1c-to-average-glucose conversion found that each 1% increase in HbA1c corresponds to roughly a 29 mg/dL increase in average glucose. But here's the surprise: even people with "normal" HbA1c can spend significant time in hyperglycemia after meals—making Time in Range a more sensitive metric for many. (DOI: 10.2337/dc08-0545)

Here's that counterintuitive symptom we mentioned earlier: One of the most overlooked causes of hyperglycemia is something you do every night—or don't do enough of. Just one night of poor sleep (less than 6 hours) can reduce your insulin sensitivity by up to 25% the next day. This means the same breakfast that normally keeps your glucose at 140 mg/dL could spike you to 180+ after a restless night. Most people blame the food. The real culprit? Last night's sleep.

⚠️ DKA Characteristics

• Who it affects: Primarily Type 1 diabetes (can occur in Type 2)
• Blood sugar: Typically >250 mg/dL (can be lower)
• Ketones: High blood/urine ketones
• Blood pH: Acidosis (pH <7.3)
• Key symptoms: Fruity breath, vomiting, abdominal pain, rapid breathing
• Onset: Develops over hours to 1-2 days

⚠️ HHS Characteristics

• Who it affects: Primarily Type 2 diabetes (often older adults)
• Blood sugar: Often >600 mg/dL (can exceed 1000)
• Ketones: Minimal or absent
• Key symptoms: Extreme dehydration, confusion, seizures, coma
• Onset: Develops over days to weeks
• Mortality: ~15% (nearly 10x higher than DKA)

💚 What Changed for Meera: After her emergency room visit, Meera learned something that transformed her relationship with glucose monitoring. She used to think hyperglycemia meant "dangerously high blood sugar"—that 487 mg/dL reading from the ER. Now she knows better. When her CGM shows 195 mg/dL after dinner, she doesn't panic. She watches her Time Above Range percentage instead: if she's spending more than 25% of her day above 180 mg/dL, that's the signal to adjust—not any single reading. Today, Meera's Time in Range is 78%, and she hasn't seen numbers above 300 in over eight months.

🔔 Set Up Smart Alerts — My Health Gheware can alert you when glucose exceeds your personalized thresholds, helping you catch hyperglycemia before it becomes severe. Set up alerts →

🔄 But here's what most people miss: Exercise can actually raise blood sugar in the short term, not just lower it. High-intensity workouts trigger stress hormones (cortisol, adrenaline) that temporarily spike glucose. And if you exercise when blood sugar is already above 250-300 mg/dL without sufficient insulin, you can push it even higher and risk ketosis. The solution? Check before you exercise—and if glucose is elevated, take a walk instead of a HIIT session. (DOI: 10.2337/dc16-2329)

🇮🇳 Hyperglycemia in India: The Numbers

According to the ICMR-INDIAB 2023 study, India has:

• 101 million people with diabetes (11.4% prevalence)
• 136 million with prediabetes (15.3% prevalence)
• Projected 134 million diabetes cases by 2045
• Prevalence projected to reach 8,585 per 100,000 by 2031

These individuals experience hyperglycemia regularly, making awareness critical.

✅ Your Action Plan: What to Do This Week

Remember Meera from the beginning of this article? She wishes someone had given her this checklist before her emergency room visit. Don't wait until crisis strikes—take action now:

1. Know your numbers: Check your fasting glucose tomorrow morning. Write it down. Is it above 100 mg/dL? That's your signal to talk to your doctor.
2. Learn your symptoms: Bookmark this page. The next time you feel unusually thirsty or tired, you'll know what to check.
3. Set up tracking: Whether it's a simple logbook or an app like Health Gheware, start recording your glucose readings and meals.
4. Know when to call: Save these emergency thresholds: 250+ with symptoms, 300+ without, 600+ is 911.
5. Tell someone: Share this guide with a family member. They should know your warning signs too.

Your first step starts tonight: Set a reminder to check your fasting glucose tomorrow morning. One number. That's all it takes to start taking control.

What blood sugar level is considered hyperglycemia?

According to ADA 2025 guidelines, hyperglycemia is defined as blood glucose above 180 mg/dL (10 mmol/L). Hospital settings define it as above 140 mg/dL. CGM users should aim to spend less than 25% of time above 180 mg/dL.

What are the main symptoms of hyperglycemia?

Common hyperglycemia symptoms include excessive thirst (polydipsia), frequent urination (polyuria), fatigue, blurred vision, headaches, and slow-healing wounds. Severe symptoms include nausea, vomiting, fruity breath odor, and confusion—which require immediate medical attention.

When should I go to the hospital for high blood sugar?

Seek emergency care if blood sugar exceeds 600 mg/dL, you experience confusion or altered mental status, have difficulty breathing, show signs of DKA (fruity breath, vomiting), or have blood sugar above 250 mg/dL with ketones present.

What is the difference between DKA and HHS?

DKA (Diabetic Ketoacidosis) mainly affects Type 1 diabetes with blood sugar above 250 mg/dL, high ketones, and acidosis. HHS (Hyperosmolar Hyperglycemic State) affects Type 2 diabetes with blood sugar often above 600 mg/dL, severe dehydration, but minimal ketones. HHS has a significantly higher mortality rate (~15%) compared to DKA.

How do I lower high blood sugar quickly?

For mild hyperglycemia: drink water to prevent dehydration, take prescribed insulin or medication, do light physical activity if safe, and avoid eating more carbs. For severe hyperglycemia (above 300 mg/dL), contact your healthcare provider before exercising as physical activity may actually worsen glucose levels in that situation.

Can hyperglycemia occur without diabetes?

Yes, stress hyperglycemia can occur during severe illness, surgery, or trauma even without diabetes. Medications like corticosteroids can also cause temporary hyperglycemia. People with prediabetes (136 million in India according to ICMR) may experience post-meal glucose spikes that meet hyperglycemia thresholds.

What is Time in Range? The Key Diabetes Metric

Understand how Time in Range and Time Above Range help you manage hyperglycemia.

Diabetes 101: Complete Beginner's Guide

Everything you need to know about diabetes management as a beginner.

Carb Counting 101: Essential Skill for Blood Sugar Control

Learn to count carbs accurately to prevent post-meal hyperglycemia.

💬 What's your biggest trigger for high blood sugar?
Share in the comments: Is it certain foods, stress, missed medications, or something else? Your experience might help others identify their patterns!