Medical disclaimer: This article is general education, not a diagnosis or treatment plan. Diabetes can become an emergency. Contact a qualified healthcare professional for personal advice. Seek urgent care for severe vomiting, trouble breathing, confusion, loss of consciousness, or signs of very high or very low blood glucose.
Medically reviewed for source accuracy on June 11, 2026. Diabetes mellitus is a group of conditions in which blood glucose remains too high because the body does not make enough insulin, does not use insulin effectively, or both.
Glucose is an important energy source. Insulin, a hormone made by pancreatic beta cells, helps glucose move from the bloodstream into many cells. Persistently high blood glucose can damage blood vessels, nerves, kidneys, eyes, and other organs over time.
Main types of diabetes
Type 1 diabetes
Type 1 diabetes is an autoimmune disease. The immune system attacks insulin-producing beta cells, so the body makes little or no insulin. It can develop at any age, although it is often diagnosed in children, teenagers, or young adults. People with type 1 diabetes require insulin to survive.
Type 2 diabetes
Type 2 diabetes is the most common type. The body’s cells become less responsive to insulin, and the pancreas may eventually be unable to produce enough to keep glucose in range. Genetics, age, body composition, activity, sleep, medications, and social and environmental factors can affect risk. It is not accurate or helpful to describe type 2 diabetes as a personal failure.
Gestational diabetes
Gestational diabetes develops during pregnancy in someone who did not already have diabetes. It often has no obvious symptoms, which is why screening is part of prenatal care. It usually resolves after delivery, but it increases the future risk of type 2 diabetes for the parent and child.
Other specific types
Diabetes can also result from genetic conditions, diseases of the pancreas, endocrine disorders, or medicines such as glucocorticoids. Clinicians use history and testing to determine the type because treatment needs differ.
Common symptoms
- Frequent urination
- Increased thirst or hunger
- Unexplained weight loss
- Fatigue
- Blurred vision
- Sores that heal slowly
- Frequent infections
- Numbness or tingling in the hands or feet
Type 1 symptoms can appear quickly and may include nausea, vomiting, stomach pain, and diabetic ketoacidosis. Type 2 diabetes can develop gradually and may cause no noticeable symptoms for years. Symptoms alone cannot confirm or exclude diabetes.
When to seek urgent care
Diabetic ketoacidosis and severe hypoglycemia are medical emergencies. Seek urgent help for difficulty breathing, fruity-smelling breath, severe dehydration, persistent vomiting, confusion, seizure, or unconsciousness. A person who is unconscious should not be given food or drink by mouth.
How diabetes is diagnosed
Healthcare professionals diagnose diabetes with blood tests. Common tests include:
- A1C: estimates average glucose exposure over roughly two to three months.
- Fasting plasma glucose: measures glucose after an overnight fast.
- Oral glucose tolerance test: measures the response to a glucose drink over time.
- Random plasma glucose: may be used when classic symptoms are present.
A result may need confirmation on another day unless symptoms and glucose levels make the diagnosis clear. Pregnancy uses specific screening and diagnostic procedures. Home glucose meters and consumer wearables are useful management tools but are not substitutes for a clinical diagnosis.
Prediabetes
Prediabetes means glucose levels are higher than normal but do not meet diabetes criteria. It increases the risk of type 2 diabetes, heart disease, and stroke. Progression is not inevitable. Evidence-based prevention programs may include sustainable activity, nutrition support, sleep, weight management when appropriate, and medication for selected people.
Risk factors
Risk factors vary by type. Type 1 diabetes involves autoimmune and genetic susceptibility that is not caused by eating sugar. Type 2 risk can be influenced by family history, age, previous gestational diabetes, polycystic ovary syndrome, physical inactivity, certain medicines, and conditions associated with insulin resistance.
Population differences also reflect access to healthcare, food environments, chronic stress, discrimination, income, and other social determinants. Race or ethnicity should not be treated as a biological explanation on its own.
Managing diabetes
Management is individualized. It may include glucose monitoring, insulin, non-insulin medicines, nutrition planning, physical activity, sleep support, blood-pressure and cholesterol management, and regular screening for complications.
- Take medicines as prescribed and discuss cost or side effects rather than stopping silently.
- Learn how food, activity, illness, stress, and medicines affect glucose.
- Know the signs and treatment plan for low blood glucose if you use insulin or medicines that can cause it.
- Attend eye, kidney, foot, dental, and cardiovascular risk checks recommended by the care team.
- Keep vaccines current based on age, health status, and local guidance.
There is no single “diabetic diet.” A registered dietitian or diabetes-care and education specialist can help build an eating pattern that respects culture, budget, medicines, preferences, and health goals.
Possible complications
Over time, high glucose and related risk factors can contribute to cardiovascular disease, kidney disease, retinopathy, neuropathy, foot ulcers, hearing problems, dental disease, and other complications. Good management reduces risk, and screening can find problems earlier.
Pregnancy with diabetes requires coordinated care because glucose levels can affect both parent and baby. Preconception planning is important for people with pre-existing diabetes who may become pregnant.
Common questions
Can eating sugar cause type 1 diabetes?
No. Type 1 diabetes is an autoimmune disease. Diet does not cause the immune attack on pancreatic beta cells.
Can a thin or active person develop type 2 diabetes?
Yes. Body size is only one factor, and people of many body types can develop type 2 diabetes.
Can diabetes be cured?
Type 1 diabetes currently requires lifelong insulin. Some people with type 2 diabetes can reach remission, but ongoing follow-up is still important because glucose can rise again.
Should I change medication based on an online article?
No. Medication changes should be made with a qualified clinician who knows your history, test results, other medicines, and risks.
