Overview
Blood sugar, also called blood glucose, is the body’s main source of energy. The hormone insulin helps move glucose from the blood into cells. Blood sugar control refers to the balance between glucose coming in from food, glucose made by the body, and how well insulin works. Problems with this balance can lead to high blood sugar, low blood sugar, prediabetes, or diabetes.
Key Symptoms
High blood sugar may cause increased thirst, frequent urination, blurred vision, tiredness, slow-healing sores, or unexpected weight loss. Low blood sugar may cause sweating, shakiness, hunger, fast heartbeat, confusion, or irritability. Some people, especially early in prediabetes or type 2 diabetes, may have no symptoms. Symptoms can vary by age, health status, and whether a person uses glucose-lowering medicines.
Causes and Risk Factors
Blood sugar can rise when the body does not make enough insulin, does not use insulin well, or releases extra glucose during stress or illness. Risk factors for long-term blood sugar problems include family history, excess body weight, physical inactivity, older age, gestational diabetes history, and some ethnic or racial backgrounds. Sleep problems, chronic stress, smoking, and certain medicines can also affect blood sugar. Conditions such as type 1 diabetes, type 2 diabetes, hormonal disorders, and pancreatic disease may play a role.
Who Is Affected
Anyone can have blood sugar problems, including children, adults, and older people. People with diabetes or prediabetes are most directly affected, but blood sugar control also matters during pregnancy and in people taking certain medicines. Access to healthy food, places to be active, healthcare, and testing can affect a person’s ability to manage risk. Communities around the world are affected, and patterns differ by genetics, lifestyle, and social conditions.
Prevention
Not all blood sugar problems can be prevented, but many cases of type 2 diabetes can be delayed or reduced through healthy habits. Helpful steps include regular physical activity, a balanced eating pattern, limiting sugary drinks, managing weight if advised, not smoking, and getting enough sleep. Regular checkups can help identify prediabetes or other risk factors early. People with a history of gestational diabetes or strong family history may benefit from earlier screening discussions.
Diagnosis and Tests
Healthcare professionals may use blood tests to assess blood sugar control, such as fasting blood glucose, A1C, or an oral glucose tolerance test. A person with diabetes may also use home blood glucose monitoring or a continuous glucose monitor if recommended by their care team. Test results are interpreted together with symptoms, medical history, medicines, and pregnancy status when relevant. Screening recommendations vary by age, risk factors, and local guidelines.
Treatment Categories
Treatment depends on the cause and whether blood sugar is high, low, or fluctuating. Common approaches include nutrition changes, physical activity, education, regular monitoring, and medicines such as insulin or other glucose-lowering treatments when prescribed. Some people also need treatment plans for low blood sugar prevention or for conditions affecting hormones or the pancreas. Ongoing follow-up is important because needs can change over time.
Diet and Lifestyle
Many people benefit from eating regular meals, choosing high-fiber foods, and paying attention to portion sizes and sugary drinks. Physical activity can help the body use insulin more effectively and support overall health. Stress management and adequate sleep may also improve blood sugar stability. If you use medicines that can lower blood sugar, ask a healthcare professional how meals, activity, alcohol, and illness may affect you.
When to Seek Medical Care
Seek medical care if you have symptoms of high or low blood sugar, repeated readings outside your target range, fainting, or trouble managing food and fluids during illness. You should also contact a healthcare professional if you have new vision changes, numbness, foot sores, frequent infections, or unintended weight loss. People who are pregnant or may be pregnant should seek advice promptly if blood sugar problems are suspected. Early care can help identify the cause and lower the risk of complications.
When It May Be an Emergency
Get urgent help right away for severe confusion, seizures, loss of consciousness, chest pain, severe trouble breathing, or signs of dehydration such as extreme weakness with persistent vomiting. Emergency care is also needed for symptoms that may suggest dangerously high or low blood sugar, especially in someone with diabetes. If the person cannot safely swallow, is not waking normally, or is getting rapidly worse, call emergency services. Follow local emergency guidance in your area.