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If you buy through links on this page, we may earn a small commission. Here’s our process. The human body naturally has sugar, or glucose, in the blood. The right amount of blood sugar gives the body’s cells and organs energy. An excess level of blood sugar is known as hyperglycemia. The liver and muscles produce some blood sugar, but most of it comes from food and drinks containing carbohydrates. The body needs insulin to keep blood sugar levels within a typical range. Insulin is a hormone that directs the body’s cells to take up glucose and store it. If there is not enough insulin or it does not work properly, blood sugar builds up. High blood sugar levels can cause health problems. This article explores what hyperglycemia feels like, why it occurs, and the signs of high blood sugar. Read on to find out more. What is hyperglycemia Hyperglycemia, or high blood sugar, is an issue that can affect people with type 1 or type 2 diabetes. There are two main types, including:Fasting hyperglycemia: Occurs when a person with diabetes has blood sugar levels above 130 milligrams per deciliter (mg/dl) after not eating or drinking for 8 hours or more.Postprandial hyperglycemia: Occurs when someone with diabetes has blood sugar levels of 180 mg/dl or higher 1–2 hours after eating. Having high blood sugar levels frequently or for prolonged periods can cause several adverse symptoms and increase the risk of severe complications over time. Symptoms Blood sugar serves as fuel for the body’s organs and functions. However, having high blood sugar does not provide a boost in energy. In fact, the opposite often happens because the body’s cells cannot access the blood sugar for energy. According to the American Diabetes Association, symptoms of hyperglycemia include:high blood sugar levelshigh levels of sugar in the urinefrequent urinationincreased thirst People can experience high blood sugar levels in the morning, especially if they have diabetes. Explore more about high blood sugar levels. Testing kits for levels of blood sugar and ketone levels are available for purchase online for home use. However, anyone who thinks they have diabetes should speak with a doctor first. How does high blood sugar affect the body High sugar in the blood can lead to several other symptoms and complications. They include:Urination and thirst: High blood sugar goes into the kidneys and urine. This attracts more water, causing frequent urination. This can also lead to increased thirst, even if someone drinks liquids.Weight loss: High blood sugar can cause sudden or unexplained weight loss. This occurs because the body’s cells are not getting the glucose they need, so the body burns muscle and fat for energy instead.Numbness and tingling: High blood sugar can also cause numbness, burning, or tingling in the hands, legs, and feet. This is due to diabetic neuropathy, a complication of diabetes that often occurs after many years of high blood sugar levels. Long-term complications Over time, high blood sugar can harm the body’s organs and systems. Damage to the blood vessels can lead to complications, including:heart attack or strokedamage to the eye and loss of visionkidney disease or failurenerve problems in the skin, especially the feet, leading to sores, infections, and wound healing problems What does high blood sugar feel like When a person has high blood sugar, they may:have a headache and other aches and painsfind it hard to concentratebe very thirsty or hungryfeel drowsy or tiredhave blurred visionfeel their mouth is dryexperience bloatingneed to urinate oftennotice that wounds take a long time to heal High blood sugar and low insulin can lead to a rise in ketones and possibly diabetic ketoacidosis (DKA), a serious complication that needs urgent medical attention. If this occurs, an individual may experience:shortness of breatha fruity taste or smell on the breatha rapid heartbeatconfusion and disorientationvomitingdehydrationcoma In addition, the person’s blood sugar levels may be over 240 mg/dl. CausesShare on PinterestGestational diabetes can occur during pregnancy. Image credit: Halfpoint/Shutterstock Several types of diabetes can lead to high blood sugar. In type 1 diabetes, the immune system attacks the cells in the pancreas that produce insulin. As a result, the body lacks insulin, and blood sugar levels rise. People with type 1 diabetes must take insulin through a needle, pen, or insulin pump to keep their blood sugar levels within the target range. Only about 5% of all those with diabetes have type 1, according to the American Diabetes Association. In type 2 diabetes, the body does produce insulin but cannot use it properly. The pancreas tries to make more of the hormone but often cannot make enough to keep blood sugar levels steady. This is known as insulin resistance. People with type 2 diabetes may need insulin, pills, dietary changes, or exercise to help manage blood sugar levels. Gestational diabetes can occur when insulin resistance and high blood sugar levels appear during pregnancy. People should monitor this during pregnancy, as it can lead to complications for the pregnant individual and their baby. Gestational diabetes usually goes away after delivery. There may also be a link between diabetes and cystic fibrosis, a genetic condition that affects the lungs, pancreas, and digestive tract. Additionally, people who take beta-blockers and certain steroids may also experience high blood sugar. Risk factors for high blood sugar Doctors do not know what exactly causes diabetes. However, some factors may increase the risk, including the below. Type 1 diabetes Researchers believe certain genetic or environmental factors may make people more likely to get type 1 diabetes. The National Institute of Diabetes and Digestive and Kidney Diseases notes certain genes play a role and that other factors — such as viruses and infections — may have an impact. The Juvenile Diabetes Research Foundation states that there is nothing a person can do to prevent type 1 diabetes. Eating, exercising, or other lifestyle choices will not change the outcome. Type 1 diabetes usually begins during childhood or early adulthood, but it can happen at any age. Type 2 diabetes The following risk factors may increase the risk of developing type 2 diabetes:having certain geneshaving overweight or obesitybeing physically inactivehaving a parent or sibling with type 2 diabeteshaving African American, Alaska Native, American Indian, Asian American, Hispanic, or Pacific Islander ethnicitybeing aged over 45 yearsreceiving treatment for high blood pressure or having blood pressure above 130/80 millimeters of mercury (mm Hg)having low levels of “good” high-density lipoprotein cholesterol or high levels of triglycerides Typical blood sugarShare on PinterestRegular blood sugar testing can help people with diabetes keep their blood sugar levels within the target level. Image credit: ChooChin/Shutterstock People who have high blood sugar should discuss their target levels with a doctor. They may need regular testing to keep these within a healthy range. Each person is different, and levels can vary between individuals. To find out their blood sugar levels, a person may need to fast for 8 hours, 2 hours after a meal, or at both times. Some people may also take a glucose tolerance test, where they drink a sugary liquid and have a blood test after. The American Diabetes Association recommends a premeal blood sugar level of 80–130 mg/dl. Around 1 to 2 hours after beginning a meal, their blood sugar should be less than 180 mg/dl. Managing blood sugar levels Many people with diabetes must check their blood sugar levels daily with a glucose meter. This device takes a drop of blood, usually from a finger, and displays the sugar level within a few seconds. People with type 1 diabetes will need to take insulin as their doctor recommends, usually several times a day. Those with type 2 diabetes or gestational diabetes may need to change their diet and exercise habits. They may also need to take oral medications or insulin. Preventing high blood sugarShare on PinterestMonitoring your diet and exercise alongside blood sugar levels can help you maintain a healthy blood sugar level. Image credit: Fertnig/iStock Various strategies can help prevent hyperglycemia. People should:Check their blood sugar levels as their doctor advises and take the correct amount of insulin if they have type 1 diabetes.Speak with a doctor or dietitian about which foods to eat or avoid, how much to eat, and how often.Take precautions to avoid infections, for example, through regular handwashing, as illness, such as a cold, can trigger an increase in blood sugar levels.Plan their food intake and exercise to balance blood sugar levels.Minimize stress as far as possible, for example, through exercise, getting enough sleep, and stress-reducing activities such as meditation or yoga. Low blood sugar or hypoglycemia Low blood sugar or hypoglycemia, can occur when a person:has certain medical conditionsuses specific medicationsdoes a lot of exerciseskips meals or eats too little It can also be a side effect of diabetes medicines. Taking too much insulin can result in low blood sugar levels. Symptoms of low blood sugar may include:feeling weak or shakysudden nervousness, anxiety, or irritabilitysweating or chillsextreme hungerconfusionfast heart rate, or palpitations A person can treat hypoglycemia rapidly by drinking fruit juice or eating a glucose tablet, sugar lump, or candy. Anyone who has frequent episodes of low blood sugar should speak with a doctor. A healthcare professional may recommend changing the type or dose of medication. When to consult a doctor Anyone who experiences tiredness, increased thirst, frequent urination, or weight loss should consult a doctor, as these symptoms could indicate diabetes or another health problem. A routine health check often involves blood sugar testing, even if the person has no symptoms. The U.S. Preventive Services Task Force recommends screening for diabetes and prediabetes for adults aged 35 to 70 years who have overweight or obesity. Those with a family history of diabetes or other risk factors may need earlier or more frequent tests. Outlook When a person has diabetes, their health and well-being depend on managing their blood sugar levels properly. To improve or maintain a good quality of life, an individual should: consult doctor regularlytake medications as a doctor has prescribedfollow diet and exercise guidelines These strategies can help a person with diabetes manage blood sugar and may also slow the progression of the condition. These individuals should also carry a medical ID with them, especially if they use insulin, as this can provide important information in case of an emergency. Many medical IDs are now available with a compact USB drive containing a person’s full medical record. Last medically reviewed on August 22, 2022DiabetesType 1Type 2 20 sourcescollapsedMedical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.Diabetes & DKA (ketoacidosis). (n.d.).https://diabetes.org/diabetes/dka-ketoacidosis-ketonesDiabetes risk factors. (2021).https://www.heart.org/en/health-topics/diabetes/understand-your-risk-for-diabetesDiabetic ketoacidosis. (2021).https://www.cdc.gov/diabetes/basics/diabetic-ketoacidosis.htmlDiabetic neuropathy. (n.d.).https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/nerve-damage-diabetic-neuropathiesDoan, L. V., et al. (2022). Cystic fibrosis related diabetes.https://www.ncbi.nlm.nih.gov/books/NBK545192/Gestational diabetes and a healthy baby? Yes. (n.d.).https://diabetes.org/diabetes/gestational-diabetesHyperglycemia (high blood glucose). (n.d.).https://diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hyperglycemiaHyperglycaemia (high blood sugar). (2021). https://www.nhsinform.scot/illnesses-and-conditions/blood-and-lymph/hyperglycaemia-high-blood-sugarHypoglycemia (low blood glucose). (n.d.).https://diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/hypoglycemiaJain, V., et al. (2017). Drugs and hyperglycemia: A practical guide [Abstract].https://pubmed.ncbi.nlm.nih.gov/28923179/Life doesn't end with type 2 diabetes. (n.d.).https://diabetes.org/diabetes/type-2Lithgow, K., et al. (2017). Polyuria: A pathophysiologic approach.https://cjgim.ca/index.php/csim/article/view/247Manage blood sugar. (2021).https://www.cdc.gov/diabetes/managing/manage-blood-sugar.htmlPrediabetes and type 2 diabetes: Screening. (2021).https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/screening-for-prediabetes-and-type-2-diabetesPut the brakes on diabetes complications. (2021).https://www.cdc.gov/diabetes/library/features/prevent-complications.htmlSymptoms & causes of diabetes. (2016).https://www.niddk.nih.gov/health-information/diabetes/overview/symptoms-causesThe big picture: Checking your blood glucose. (n.d.).https://diabetes.org/healthy-living/medication-treatments/blood-glucose-testing-and-control/checking-your-blood-sugarType 1 diabetes facts. (n.d.). http://www.jdrf.org/about/fact-sheets/type-1-diabetes-facts/Type 1 diabetes: The basics. (2019).https://diabetes.org/blog/type-1-diabetes-basicsWhat is diabetes? (2016).https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes?FEEDBACK:Medically reviewed by Avi Varma, MD, MPH, AAHIVS, FAAFP — By Jennifer Berry — Updated on September 1, 2022 Latest newsWhat sets 'SuperAgers' apart? Their unusually large neuronsOmega-3 may provide a brain boost for people in midlifeSeasonal affective disorder (SAD): How to beat it this fall and winterCDC: Monkeypox in the US 'unlikely to be eliminated in the near future'Why are more women prone to Alzheimer's? New clues arise Related CoverageWhat are the differences between type 1 and type 2 diabetes?Medically reviewed by Michelle L. Griffith, MD Type 1 and type 2 diabetes both relate to the body’s use of insulin but have different causes and treatments. Find out here about the differences and…READ MOREAre apples good for diabetes?Medically reviewed by Natalie Olsen, R.D., L.D., ACSM EP-C Apples may be a good choice for people with diabetes. 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