What causes high blood sugar?

If you have diabetes, exercise, extra fluids, and insulin are easy ways to lower blood sugar levels naturally. It’s important to know when to use at-home treatment and when you need emergency medical treatment, though.
The medical term for high blood sugar is hyperglycemia. It happens when there’s too much sugar, or glucose, in your blood.
A hormone called insulin carries glucose through your blood. If you don’t have enough insulin or your body can’t use insulin, glucose can build up in your blood and cause problems. This commonly affects people who have diabetes, including type 1, type 2, or diabetes while you’re pregnant called gestational diabetes.
Lots of things can cause high blood sugar, including:
- Over-treating low blood sugar
- Stress
- Eating too much
- Not eating the right foods
- Not enough exercise
- Sickness
- Some medications, like corticosteroids
- Missing your diabetes medication
If you have diabetes, you’re likely to have high blood sugar once in a while no matter how careful you are. In most cases, it will be mild and you can easily treat it with some adjustments. If your levels get very high or stay high for a long time, you can have complications.
For example, with type 1 diabetes, you can get diabetic ketoacidosis where your body breaks down your fat to use as energy and releases toxic acids into your blood. With type 2 diabetes, you can become dehydrated as your body tries to get rid of extra sugar. The longer your sugar is high, the more serious your symptoms become.
It’s important to follow your treatment plan and monitor your blood sugar. A high blood sugar level is:
- 125 milligrams per deciliter after not eating for 8 hours
- 180 milligrams per deciliter 2 hours after eating
What is the quickest natural way to lower blood sugar?
You can prevent high blood sugar with healthy eating, regular physical activity, and stress management. You might still have occasional periods of high blood sugar, though. With time, you can learn the signs and take steps to treat it early.
Exercise
Exercise is an important part of managing your blood sugar and diabetes. When you exercise, your muscles use glucose for energy and it helps your body better respond to insulin. Moderately intense exercise or a new type of exercise can lower your blood sugar even up to a day later.
But keep in mind that some types of exercise can have the opposite effect. Some intense workouts make your blood release stress hormones. These hormones stimulate your liver to release glucose, which raises your blood sugar level. Exercises like sprints, heavy weightlifting, and sports might make your blood sugar worse.
If your blood sugar is mildly high, try exercising to lower it. Stick to moderate aerobic exercise, a brisk walk, or weight training with light weights. Test your blood sugar after your workout to track the effects.
Don’t exercise if you have ketones in your urine or your blood sugar is 250 milligrams per deciliter or higher. Otherwise, you might make your blood sugar go even higher.
Drink lots of water
Your kidneys filter your blood and remove wastes and extra fluids. When you have too much glucose, your kidneys have to work harder to filter and absorb or remove the glucose. If they can’t keep up, they’ll dump the extra glucose into your urine to get rid of it.
The result is increased urination and you’ll end up getting rid of more body fluids than necessary, which causes dehydration. This will make you thirsty, and as you drink more fluids, you’ll urinate, leading to a vicious cycle.
But drinking extra water will help dilute extra glucose in your blood. Plus it will help you stay hydrated, too. If your sugar is high, drink plenty of water. You can also have other drinks like tea, coffee, or sparkling water as long as it’s sugar-free.
Take your insulin correctly
If you take insulin, adjust your dose or take a short-acting insulin supplement. The extra dose might help correct your high blood sugar. You can ask your doctor about how often to take extra insulin.
Sometimes your levels can also fluctuate if you miss a dose or you don’t take your insulin or medication correctly. Make sure you follow your prescription instructions.
Monitor your blood sugar
After you adjust, keep monitoring your blood sugar to see if it changes and comes back into a healthy range. Watch for signs and symptoms of a more serious problem until your sugar is back under control.
When to go to the emergency room for high blood sugar
You should go to the emergency room if you have high blood sugar that stays at 240 milligrams per deciliter or higher and you have ketones in your urine.
You should also go if you have high blood sugar and the following symptoms:
- Throwing up
- Diarrhea
- Stomach pain
- Headache
- Dry skin
- Weak and fast pulse
- Fast breathing
- Trouble staying awake
- Fever for 24 hours or longer
- Fruity-smelling breath
- Flushed face
These can be signs of diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS), which results from dehydration. If you have these symptoms, test your urine for ketones, which are toxic acids that cause DKA.
DKA is a medical emergency and can lead to coma or death. It’s more common in type 1 diabetes, though you can have it with other types. You can’t treat this at home as you need help to lower your blood sugar.
When to see a doctor
Sometimes you can correct high blood sugar and you don’t need emergency treatment. There are times you should book an appointment to talk to your doctor, though. These include when:
- You have high blood sugar a lot
- Your blood level is 240 milligrams per deciliter even after you’ve taken your insulin
- You’re struggling with your diet plan, which affects your blood sugar
- You’re worried about your symptoms
You should also have check-ups at least twice a year to monitor your treatment plan. If you’re struggling to keep your levels in a healthy range, you might need changes to your medication or diet plan.

SLIDESHOW
Diabetes: What Raises and Lowers Your Blood Sugar Level? See SlideshowAmerican Diabetes Association: "Hyperglycemia (High Blood Sugar)."
Centers for Disease Control and Prevention: "Manage Blood Sugar."
Cleveland Clinic: "Hyperglycemia (High Blood Sugar)."
Harvard Medical School Harvard Health Publishing: "The importance of exercise when you have diabetes."
Mayo Clinic: "Diabetes management: How lifestyle, daily routine affect blood sugar," "Diabetes symptoms: When diabetes symptoms are a concern," "Hyperglycemia in diabetes."
National Health Service: "Hyperglycaemia (high blood sugar)."
NHS Inform: "Hyperglycaemia (high blood sugar)."
National Institutes of Health National Institute of Diabetes and Digestive and Kidney Diseases: "Managing Diabetes."
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