Dangers of Uncontrolled Blood Sugar

Medically Reviewed by Michael Dansinger, MD on February 03, 2023
3 min read

If your blood sugar is too high for too long, it can cause serious health problems. It’s something to be careful of whether you have diabetes or not.

How high is too high? Your doctor will tell you what your target range should be and what to do if your levels aren’t in that range. If you have diabetes, you'll need to check your blood sugar, also called glucose, to know if it’s too high, too low, or meets your goal.

A diabetic coma could happen when your blood sugar gets too high -- 600 milligrams per deciliter (mg/dL) or more -- causing you to become very dehydrated.

The problems that high blood sugar can cause happen over time. The sooner you get your levels back in line, the better.

The symptoms can include:

  • Feeling thirstier than usual
  • Blurred vision
  • Having to pee more often
  • Feeling hungrier than normal
  • Numb or tingling feet

You might also feel more tired than usual, get infections on your skin, or notice that cuts and sores take a long time to heal.

Tell your doctor if you have any of these symptoms.

High glucose levels can affect you from head to toe. If they're out of control for a long time, you could have some or all of the following:

  • Heart disease or heart attack
  • Stroke
  • Kidney damage
  • Nerve damage
  • Eye damage
  • Skin problems

Once your doctor spots the early signs, they may send you to the hospital. You’ll get an IV to replace lost fluids and electrolytes such as potassium. And you’ll get insulin or other medication to control your blood sugar. 

If you go into a diabetic coma, you could die if it’s not treated.

Pick up the phone if your blood sugar is high and you have any of these symptoms:

  • Trouble breathing
  • Vomiting
  • Being very tired
  • Stiff or achy muscles
  • Extreme thirst or a very dry mouth
  • Having to pee too often
  • Dry or flushed skin
  • Breath that smells like fruit
  • Confusion

These are symptoms of diabetic ketoacidosis (DKA). Your body burns blood sugar for energy. When your cells don’t get enough of it, they burn fat. That produces chemicals called ketones. When these build up, your blood becomes more acid-like. This can be life-threatening if it’s not treated.

Take these simple steps to help protect yourself:

  • Check your blood sugar regularly, as your doctor recommends.
  • Know your target blood sugar ranges and what to do if the readings are too high.
  • Plan how often to check your blood sugar when you’re sick.
  • Take extra care of yourself if you’re ill.

This mostly affects elderly people. As glucose builds up in your blood, your body tries to get rid of it through your urine.

At first, you pee a lot. Over time, you pee less, but when you do, it’s very dark. This condition can lead to dehydration, coma, and death.

Call 911 right away if you have any of these warning signs:

  • Blood sugar level over 600 mg/dL
  • Extreme thirst that may later go away
  • Warm, dry skin that doesn’t sweat
  • Fever over 101 F
  • Sleepiness or confusion
  • Weakness on one side of your body
  • Vision loss
  • Hallucinations

You can avoid many of these problems by keeping your blood sugar under control. Follow your doctor’s advice about diet and exercise, take your medicine, keep up with your doctor visits, and check your levels often.