Hyperglycemia vs Hypoglycemia: What’s the Difference?

Roni Shye
Roni Shye, PharmD BCGP BCACP, is a licensed pharmacist in the states of Florida, Ohio, and Pennsylvania.
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If you have diabetes, you’re likely well aware of the issues that can come with blood sugar levels that are too high—or too low. Hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) may sound similar, but they can have very different consequences.

Using too much or too little insulin can affect your blood sugar levels, but even if you aren’t diabetic, you should know that side effects of other medications, not eating enough (or eating too much), or even exercising more than usual can all affect your blood sugar. The scary part? Some people don’t have many symptoms, and may not be able to tell that their blood sugar is too high or too low without a glucose meter check.

So what’s the difference, and how can you avoid hyper- and hypoglycemia?

Hypoglycemia (Low Blood Sugar)

Low blood sugar can be caused by not eating enough food or a delayed meal, an unusual amount of exercise, and drinking alcohol without eating food. If you use insulin, you know that your blood sugar levels can go too low if you use too much of your medication.

Symptoms of hypoglycemia include sweatiness, shaking, dizziness, confusion, a fast heartbeat, hunger, feeling weak or tired, feeling nervous or upset, or headache.

Will I notice if my blood sugar is low?

Maybe. You may experience some of the symptoms mentioned above like feeling sweaty, shaky, or dizzy; a fast heartbeat; or feeling hungry. However, some people don’t feel anything at all.

Hypoglycemia unawareness is the term for not being able to tell if your blood sugar is low, and it can be very dangerous.

How can I know if my blood sugar is low if I don’t notice any symptoms?

You’ll need to use a blood glucose meter, which can determine the amount of sugar in your blood using a small drop of blood typically from your finger tip, although some meters allow you to test from sites other than your fingertip.

How can I treat low blood sugar?

A quick sugar source containing at least 15 grams of carbohydrates is effective—this is known as the rule of 15. Some examples include:

How can I make sure my blood sugar doesn’t get too low?

It’s important to make sure you eat a meal or snack containing protein—this will help keep low blood sugar from coming back.

What risks are associated with low blood sugar?

Severe low blood sugar is an emergency is usually requires help from someone else.

Hyperglycemia (High Blood Sugar)

High blood sugar can be caused by certain medications, stress, having a cold or other infection, and eating certain foods. If you use insulin, you know that not using enough, or using damaged or out of date insulin can also let your blood sugar levels get too high.

Early symptoms of high blood sugar include frequent urination, increased thirst, blurred vision, headache, and tiredness.

Later and more serious symptoms include fruity or alcoholic smelling breath, dry mouth, confusion, weakness, stomach pains, general aches, shortness of breath. You may have a loss of appetite and nausea and vomiting. If you are measuring your glucose and ketone levels, you would see large amounts of sugar in the blood and ketones in the urine.

Will I notice if I have high blood sugar?

The symptoms of high blood sugar may be easier to spot. If you’re thirstier than usual, frequently urinating, and tired, you may want to check your blood sugar, or see your doctor.

How can I keep my blood sugar low?

Healthy diet, exercise, and lowering stress levels can all help keep your blood sugar levels low. If you have a fasting blood sugar level high enough to be considered diabetes, your doctor may also prescribe medications like metformin or insulin to help control your blood sugar levels.

What risks are associated with high blood sugar?

Severe high blood sugar can result in diabetic ketoacidosis or DKA. DKA occurs when there isn’t enough insulin in the body, and while it can mean you haven’t used enough insulin, it can also be triggered by infection or other illnesses.

This condition is where you’ll see the more severe symptoms, including thirst, frequent urination, nausea, abdominal pain, weakness, fruity-scented breath, and confusion.

If you think you may be experiencing DKA, contact your doctor immediately.

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