What Is The Difference Between Hyperglycemia and Hypoglycemia?

What Is the Difference Between Hyperglycemia and Hypoglycemia?

Written by Susan Weiner, MS, RDN, CDN, CDCES ,FADCES 

Hyperglycemia (high blood sugar), refers to abnormally elevated levels of glucose in the blood1, whereas hypoglycemia (low blood sugar) indicates low levels of glucose in the blood (less than 70 mg/dL)2. While hyperglycemia and hypoglycemia may sound similar, they have different symptoms, triggers and health effects. If you are living with diabetes, it’s important to understand how to manage or potentially prevent frequent high and low blood glucose values. 

To understand hyperglycemia and hypoglycemia it is also important to understand insulin. Insulin is a hormone produced by a functioning pancreas that is released when glucose enters the blood stream after eating carbohydrates. Insulin acts as a shuttle moving the glucose from the bloodstream to the cells to be used for energy or stored for later use.1 

Hyperglycemia occurs when the body has too little insulin for the amount of glucose in the bloodstream or when the body can't use insulin properly.1  Common symptoms of hyperglycemia include increased thirst, fatigue, headaches, blurred vision, and frequent urination as the body works to eliminate the extra glucose.1 

Factors which may contribute to hyperglycemia include, but are not limited to, expired insulin, problems with insulin absorption, eating a large amount of carbohydrate without adequate insulin coverage, physical inactivity, stress, illness, infection, or the dawn phenomenon (a surge of hormones during early morning hours).1 To help potentially reduce incidences of hyperglycemia it is important to take insulin/medications as prescribed, monitor blood glucose levels, manage stress as best as possible, and make appropriate adjustments to your meal-plan.  

Identifying and resolving prolonged hyperglycemia are key to preventing negative health effects and complications including: potential damage to nerves, eyes, skin and blood vessels. If you are living with diabetes, it’s vitally important to recognize the signs and symptoms of hyperglycemia because, if left untreated (e.g. insulin is not properly administered or is unavailable), it can potentially lead to diabetic ketoacidosis (DKA).4 DKA may occur when the body doesn’t have enough insulin and therefore can’t properly use glucose which is the body’s main source of energy. Instead, fat and muscle are broken down for energy leading to excessive ketone production.4 The build-up of ketones in the blood makes the blood more acidic and may lead to metabolic acidosis. When ketone levels get too high, you may develop dangerous DKA, which happens most often in people with type 1 diabetes, although it can occur in some people living with type 2 diabetes.4 

Hypoglycemia, can occur in people living with diabetes who take insulin or other glucose lowering medications.  Hypoglycemia occurs when the body has too much insulin for the amount of glucose in the bloodstream. It can occur with or without symptoms.2 

Hypoglycemia may be triggered by missing a meal or eating later than planned, increased or unplanned physical activity, drinking alcohol on an empty stomach, taking too much insulin for the amount of carbohydrate eaten, or making a mistake with insulin dosing.5 Symptoms of hypoglycemia may include increased hunger, shakiness, rapid heartbeat, blurry vision, irritability, and confusion.5 

Severe hypoglycemia will require immediate medical attention and glucagon may need to be administered.6 Hypoglycemia can also significantly negatively impact cardiovascular health.7 Additional health effects of hypoglycemia may include seizures and loss of consciousness and may negatively affect emotional well-being.2 It is therefore important to be aware of the signs and symptoms of hypoglycemia, as well as the potential causes and available treatments.  

Every individual living with diabetes is unique, so please speak with your physician or health care professional to discuss what target blood glucose range may be best for you. It’s important to ask any questions you might have about blood glucose monitoring and how best to prevent and manage blood glucose fluctuations. You don’t have to do this alone! 

1: Hyperglycemia (high blood glucose). Hyperglycemia (High Blood Glucose) | ADA. https://www.diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hyperglycemia. Accessed November 5, 2021.
2: Low blood glucose (hypoglycemia). National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/low-blood-glucose-hypoglycemia. Accessed November 6, 2021.
3: Diabetes complications. Diabetes Complications | ADA. https://www.diabetes.org/diabetes/complications. Accessed November 6, 2021.
4: DKA (ketoacidosis) & ketones. DKA (Ketoacidosis) & Ketones | ADA. https://www.diabetes.org/diabetes/complications/dka-ketoacidosis-ketones. Accessed November 6, 2021.
5: Low blood sugar (hypoglycemia). Centers for Disease Control and Prevention. https://www.cdc.gov/diabetes/basics/low-blood-sugar.html. Published March 25, 2021. Accessed November 6, 2021.
6: Hypoglycemia (low blood glucose). Hypoglycemia (Low Blood Glucose) | ADA. https://www.diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hypoglycemia. Accessed November 6, 2021.
7: Snell-Bergeon JK, Wadwa RP. Hypoglycemia, diabetes, and cardiovascular disease. Diabetes technology & therapeutics. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3361183/. Published June 2012. Accessed November 6, 2021.

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