Hyperglycemia (high blood sugar)

Hyperglycemia (also called a hyper) is the medical term for high blood sugar (also known as high blood glucose). High blood sugar happens when the body has too little insulin or can’t use insulin properly. It is a common occurrence for people with diabetes.

Blood sugar control is key to managing diabetes and the aim of treatment is to keep your blood sugar levels to as near to normal as possible. Regularly having high blood sugar levels for long periods of time can result in permanent damage to parts of your body such as eyes, nerves, kidneys and blood vessels. The good news is that significant studies show that effectively controlling blood sugar levels will reduce those risks.1,2

If you have diabetes, it’s very likely you will experience high blood sugar at some point, no matter how careful you are. It’s important to be able to recognize and treat hyperglycemia in order to reduce the chance of serious health problems.

What causes high blood sugar?

A number of factors can contribute to high blood sugar. It may be that:

  • If you have type 1 diabetes, you may not have given yourself enough insulin
  • If you have type 2 diabetes, the insulin your body produces may be enough, but is not as effective as it should be
  • Are stressed
  • Have an illness (such as a cold)
  • Have eaten more carbohydrate than your body can cope with
  • Are less physically activity than usual
  • Have missed a dose of your diabetes medicine or have taken an incorrect dose
  • Have overtreated an episode of low blood sugar (hypoglycemia)
  • Are taking certain medicines, such as steroids

How do I know if my blood sugars are high?

Symptoms of high blood sugar in people with diabetes tend to develop slowly over a few days or even weeks. For some people, there may be no physical symptoms until the blood sugar level is very high.

Symptoms of high blood sugar include: increased thirst, needing to pee frequently, recurrent infections such as thrush, bladder infections and skin infection, extreme hunger, tiredness, or unintended weight loss. 3,4

How do I treat high blood sugar?

Treating high blood sugar generally depends on what has caused it. If you have regular occurrences, you should consult with your health care team to review your medicines and/or lifestyle.

You may be advised to:

  • change your diet
  • drink plenty of sugar-free fluids
  • do gently, regular exercise
  • if you use insulin, you may be advised to adjust your dose

If your blood sugar levels are over 250-300 mg/dL, you should check your urine for ketones. Ketones appear in your urine when your body is breaking down fats for energy, and for people with diabetes, this is an indication that the management of your diabetes needs adjusting. Ketones are more common in someone with type 1 diabetes. They may be present if you have an illness, are dehydrated or have lost weight. Ketones may also appear in someone with type 2 diabetes in the case of illness.

If you have ketones in your urine you should:

  • Correct your dose of insulin and recheck your blood glucose in 1-2 hours.
  • Keep drinking water and rest – do not exercise as this can increase the amount of ketones
  • See your health care team to review your treatment plan
  • If you have the following symptoms you should call your doctor as soon as possible:
    • Your blood sugar levels are not going down
    • Stomach pains
    • Nausea and/or vomiting
    • Breathlessness
    • Your breath smells fruity
    • Acetone in your urine is an extreme condition and you should go directly to the emergency room for treatment.3,4

How do I prevent high blood sugars?

In order to keep your blood sugar levels in a healthy range you need to follow your meal plan, exercise program, and medicine schedule. It is important that you:

  • Understand the effect of nutrition, different types of food and how they influence on your personal blood sugar levels
  • Check the influence of type and intensity of exercise on your sugar levels
  • Stay aware of your blood sugar levels by consistently monitoring with Dario, especially in exceptional situations such as sick days, change in dietary habits or physical activity, drug therapy or stress situations 3,4

Medical Disclaimer
The articles provided on this website are for informational purposes only. In addition, it is written for a generic audience and not a specific case; therefore, this information should not be used for diagnostic or medical treatment. This site does not attempt to replace the patient-physician relationship and fully recommends the reader to seek out the best care from his/her physician and/or diabetes educator.


“The UK Prospective Diabetes Study (UKPDS): clinical and therapeutic implications for type 2 diabetes” Br J Clin Pharmacol. 1999 Nov; 48(5): 643–648

“The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study at 30 Years: Overview” David M. Nathan et at. Diabetes Care Volume 37, January 2014

“Complete nurse’s guide to Diabetes care” Belinda P. Childs et al American Diabetes Association 2017.

Diabetes Care, American Diabetes Association, 2019 

DAR-0139 RevA 08/2019