What Is Hyperglycemia and How Do You Manage It?

Health Line

11-07-2025

Key takeaways
Hyperglycemia (high blood sugar) can develop over time and may not be immediately noticeable, but it can lead to serious health issues if not addressed. It may be caused by not getting the right dosage of insulin, eating more carbs than usual, illness, and infection, among others.
Symptoms may include excessive thirst, excessive urination, blurry vision, fatigue, and sores that won't heal. In severe cases, hyperglycemia may cause diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar syndrome (HHS).
Managing blood sugar levels through regular monitoring, managing diabetes, exercise, and a balanced diet are key to preventing and treating hyperglycemia.
Several factors can contribute to hyperglycemia, including dietary choices and a sedentary lifestyle. Chronic high blood sugar is a symptom of diabetes.
Regular blood glucose testing is crucial for people with diabetes. This is because many people don't feel the effects of hyperglycemia.
Symptoms of hyperglycemia
According to the Centers for Disease Control and Prevention (CDC), target blood glucose levels for people with diabetes are typically:
between 80 and 130 mg/dL before you've eaten
under 180 mg/dL 2 hours after the first bite of your meal
Blood sugar levels that are higher than that may indicate unmanaged or undiagnosed diabetes or a need to adjust your diabetes treatment.
You may not feel the effects of hyperglycemia until levels are very high for an extended period of time. If you experience symptoms of hyperglycemia, it's important that you check your blood glucose levels and connect with a doctor.
Hyperglycemia symptoms that may develop over several days or weeks include:
The longer the condition is left untreated, the more severe it may become. Long-term effects of hyperglycemia include:
eye disease
kidney disease
cardiovascular disease
neuropathy, or nerve damage
Medical emergencies
Diabetic ketoacidosis (DKA) and hyperglycemic hyperosmolar syndrome (HHS) are two conditions caused by very high glucose levels. Contact a doctor straight away if you suspect you've developed DKA or HHS.
DKA generally occurs in people with type 1 diabetes and is less common with type 2 diabetes. However, not everyone with these blood glucose levels will have DKA.
In addition to the usual symptoms of hyperglycemia, a person with DKA may also have:
ketonuria, or a higher-than-usual amount of ketones in their urine
breath that smells fruity
gastrointestinal issues, such as nausea, vomiting, or pain
dry skin
confusion
People with HHS typically have a blood glucose level over 600 mg/dL. In addition to excessive thirst and urination, symptoms may include:
fever
dehydration
neurological symptoms, such as confusion or delirium
Hyperglycemia causes
A number of factors can contribute to hyperglycemia, including:
not getting the right dosage of insulin or other glucose-lowering medication
eating more carbohydrates than usual
being less physically active than usual
illness or infection
high levels of stress
physical trauma, such as an orthopedic injury
If you have diabetes, you may also experience regular episodes of high blood sugar between 3 a.m. and 8 a.m., before you have eaten anything. This is known as the Dawn phenomenon. You could also experience the Somogyi effect, which is where you take insulin before bed and wake up with high blood sugar.
Treatment for hyperglycemia
Several treatments are available for chronic high blood sugar.
Monitor your glucose levels
An important part of managing diabetes is checking your blood glucose levels often, such as before you eat, after you eat, or at bedtime.
Then, record that number in a notebook, blood glucose log, or blood glucose tracking app so you and your doctor can monitor your treatment plan.
Knowing when your blood glucose levels are getting out of your target range can help you get your blood glucose back on track before more significant complications arise.
Get moving
Exercise is one of the best and most effective ways to keep your blood glucose levels where they should be and lower them if they get too high.
If you're on medications that increase insulin, talk with your doctor to determine the best times to exercise. If you have complications such as nerve or eye damage, ask your doctor which exercises might suit you best.
The American Diabetes Association notes that if your blood glucose level is above 240 mg/dL, your doctor may want to check your urine for ketones.
Exercising when ketones are in your body may cause your blood glucose level to rise even higher. While it's rare for those with type 2 diabetes to experience this, if you have high blood glucose and ketones, you should avoid exercise.
Analyze your eating habits
Work with a dietitian or nutritionist to construct a nutritious, interesting selection of meals that can help you manage your carbohydrate intake and prevent higher blood glucose levels.
Diet plans you may want to explore include:
the keto diet, which is low carb and high fat
the Mediterranean diet
the Dietary Approaches to Stop Hypertension (DASH) diet
a vegetarian or vegan diet
Evaluate your treatment plan
Your doctor may reevaluate your diabetes treatment plan based on your personal health history and your experiences with hyperglycemia. They may change the amount, type, or timing of your medication.
Don't adjust your medications without first talking with your doctor or diabetes educator.
Preventing hyperglycemia
A few lifestyle changes may help prevent hyperglycemia. Try the tips below:
Test yourself regularly: Test and record your blood glucose levels on a regular basis each day. Share this information with your doctor at every appointment.
Manage your carb intake: Know how many carbohydrates you're getting with each meal and snack. Strive to stay within the range approved by your doctor or dietitian. Keep this information with the records of your blood glucose levels.
Be diabetes smart: Have an action plan for if and when your blood glucose reaches certain levels. Take your medication as prescribed, being consistent about the amount and timing of your meals and snacks.
Have alcohol in moderation: Although hypoglycemia is a more likely outcome, drinking large amounts of alcohol can eventually lead to high blood glucose levels. If you're having alcohol, choose a drink that's low in carbs and sugar.
Wear medical identification: Medical bracelets or necklaces can help alert emergency responders to your diabetes if there's a greater problem.
When to contact a doctor
Seek immediate medical attention if you experience symptoms of DKA or HHS, like:
shortness of breath
nausea or vomiting
fever
confusion
dry mouth
Contact a doctor if your blood glucose readings are consistently high, whether in a fasting state or after meals. Also, let your doctor know if their recommended lifestyle measures are not making a difference in your readings.
Make an appointment if you notice new or worsening issues with your vision or skin or if you suspect you have nerve damage or other health issues that relate to high blood sugar.
To prepare for your appointment:
Bring a record of your blood sugar readings, including when your readings were taken and whether they were taken with or without food.
Pay close attention to any instructions a medical professional gives you regarding blood work — you may need to fast.
Bring a list of your current medications and supplements, as well as a list of questions to ask your doctor.