What Is Diabetes? Types, Symptoms & Management
Updated: 6 days ago
Written by Dr. Zack Ferris in TheSkyMeds Editorial Standards
Medically reviewed by Jonathan Reed, Medical Content Reviewer Jan 28 2026
Diabetes is a chronic condition in which the body cannot regulate blood glucose, commonly called blood sugar, properly. If you are wondering what is diabetes, the problem involves insulin—a hormone that helps glucose move from the bloodstream into cells where it can be used for energy. Diabetes develops when the body does not produce enough insulin, cannot use insulin effectively, or both. Persistently high blood glucose can gradually damage blood vessels and organs, including the heart, kidneys, eyes and nerves. The main forms are type 1 diabetes, type 2 diabetes and gestational diabetes, and their causes and treatment differ. Diabetes can be managed effectively, but good care involves more than lowering one blood-sugar reading: healthy eating, physical activity, appropriate medicines, monitoring and screening for complications all play important roles.
What Is Diabetes and What Happens in the Body?
Diabetes occurs when glucose remains in the bloodstream at abnormally high levels because the insulin system is not working normally. Insulin is made by beta cells in the pancreas and helps regulate how the body uses and stores glucose.
After you eat carbohydrate-containing foods, digestion releases glucose into the bloodstream. The pancreas normally responds by releasing insulin, which helps glucose enter cells.
In diabetes, that process is disrupted. The exact reason depends on the type of diabetes.
The World Health Organization explanation of diabetes describes diabetes as a condition in which the body cannot regulate blood glucose properly because it does not produce enough insulin or cannot use insulin effectively.
Why is high blood sugar harmful?
A temporary rise in glucose after eating is normal. The concern in diabetes is glucose remaining above a healthy range over time.
Persistent hyperglycaemia—the medical term for high blood glucose—can damage blood vessels and nerves. This helps explain why diabetes can eventually affect the heart, brain, kidneys, eyes, feet and other parts of the body.
What Are the Different Types of Diabetes?
The three main types are type 1 diabetes, type 2 diabetes and gestational diabetes. They all involve abnormal blood-glucose regulation, but they develop for different reasons and should not be treated as the same disease.
Type 1 diabetes
Type 1 diabetes is an autoimmune condition. The immune system mistakenly attacks the insulin-producing beta cells in the pancreas, eventually leaving the body unable to produce enough insulin.
People with type 1 diabetes therefore require insulin treatment. Although type 1 is commonly diagnosed in children and younger adults, it can develop at any age.
Type 1 diabetes is not caused simply by eating too much sugar or having an unhealthy lifestyle. WHO currently states that there is no established way to prevent type 1 diabetes.
Type 2 diabetes
Type 2 diabetes is the most common form. WHO reports that more than 95% of people with diabetes have type 2.
It usually involves insulin resistance, meaning the body's cells do not respond normally to insulin. Over time, the pancreas may also become unable to produce enough insulin to keep glucose adequately controlled.
Genetics, ageing and lifestyle-related factors can all contribute. The condition is therefore more complex than simply saying someone developed diabetes because they ate too much sugar.
Gestational diabetes
Gestational diabetes develops during pregnancy when blood glucose becomes higher than normal but does not meet the criteria for diabetes outside pregnancy. It requires monitoring and management because elevated glucose can affect both pregnancy and the developing baby.
Women who have experienced gestational diabetes have a higher future risk of developing type 2 diabetes. Their children also have a greater risk of developing type 2 diabetes later in life.
Are there other types of diabetes?
Yes. Diabetes can also occur because of particular genetic conditions, pancreatic disease, endocrine disorders or certain medicines.
These less common forms demonstrate why identifying the type of diabetes matters. Treatment that is appropriate for one form may not be appropriate for another.
Type | What happens | Typical treatment approach | Can it be prevented? |
Type 1 diabetes | Autoimmune destruction of insulin-producing cells leads to severe insulin deficiency | Insulin is essential, alongside glucose monitoring, nutrition, activity and ongoing care | No established prevention method at present |
Type 2 diabetes | Insulin resistance develops and insulin production may become insufficient | Lifestyle measures plus individualized oral/injectable medicines and sometimes insulin | Risk can often be reduced or development delayed |
Gestational diabetes | High blood glucose develops during pregnancy | Nutrition, physical activity and glucose monitoring; medication or insulin may be required | Risk can sometimes be reduced, but not every case is preventable |
Other specific types | May result from genetic conditions, pancreatic disease, medicines or other causes | Depends on the underlying cause | Depends on the specific type |
What Are the Common Symptoms of Diabetes?
Common diabetes symptoms include increased thirst, frequent urination, unusual hunger, tiredness, blurred vision and unexplained weight loss. However, type 2 diabetes may produce few or no noticeable symptoms for years.
That means feeling well does not necessarily rule out diabetes.
Early symptoms to notice
Possible symptoms include:
feeling unusually thirsty;
urinating more frequently;
feeling unusually hungry;
unexplained tiredness or weakness;
blurred vision; and
losing weight without trying.
Other symptoms can include slow-healing wounds, recurrent infections, tingling or numbness in the hands or feet, and changes in skin or vision, although these symptoms can have many causes other than diabetes.
Do type 1 and type 2 diabetes cause symptoms differently?
They can. Type 1 diabetes symptoms commonly appear more rapidly, sometimes developing over days or weeks. Symptoms may be pronounced and can progress to nausea, vomiting or rapid breathing when glucose becomes dangerously high.
Type 2 diabetes is often less obvious. Symptoms can develop gradually and may remain mild enough to go unnoticed for years.
Diabetes does not always make you feel ill. Type 2 diabetes can remain relatively silent while high glucose gradually damages blood vessels and nerves, which is why appropriate testing matters for people with symptoms or increased risk.
How Is Diabetes Diagnosed?
Diabetes is diagnosed with blood tests rather than symptoms alone. Common tests include fasting plasma glucose, HbA1c, an oral glucose tolerance test and, in appropriate circumstances, random plasma glucose.
The WHO guidance on diabetes diagnosis and blood tests identifies these major approaches and explains that the appropriate test depends on the clinical situation.
What does an HbA1c test measure?
HbA1c gives an indication of average blood glucose over approximately the previous two to three months.
Unlike a fasting glucose test, it does not simply show what your glucose is at one moment. However, HbA1c can be less reliable in some medical situations, so clinicians interpret it alongside the individual's health and other test results.
What other tests are used?
A fasting plasma glucose test measures glucose after an overnight fast. An oral glucose tolerance test checks how the body handles glucose after a measured glucose drink.
A random plasma glucose test can also support diagnosis when someone has classic symptoms of high blood sugar or is experiencing a hyperglycaemic crisis.
A single home glucometer reading should not normally be used to diagnose diabetes independently. Formal diagnosis should be made using appropriate clinical testing and interpretation.
How Is Diabetes Managed?
Diabetes management aims to keep glucose within an individually appropriate range while reducing the risk of complications and treatment-related problems such as low blood sugar. Treatment depends strongly on the type of diabetes and the person's overall health.
WHO describes diabetes management as a combination of healthy eating, physical activity, glucose monitoring, medication when needed, self-management support, cardiovascular risk management and regular screening for complications.
Healthy eating
There is no single food that causes or cures diabetes, and there is no one diabetes diet suitable for everybody.
A balanced eating pattern generally emphasizes nutrient-rich foods, appropriate portions and carbohydrate quality while limiting excess energy, added sugars and unhealthy fats. The plan should also consider culture, affordability, preferences, weight goals, medicines and other health conditions.
People taking insulin or medicines capable of causing hypoglycaemia may need more specific guidance about carbohydrate intake and meal timing.
Physical activity
Regular activity can improve overall health and is particularly important in type 2 diabetes because physical activity can improve insulin sensitivity. Exercise also supports cardiovascular fitness, strength, mobility and weight management.
Activity should be adapted for people with complications such as cardiovascular disease, significant neuropathy, foot problems or eye disease. Someone starting a demanding exercise programme with diabetes complications may need individualized clinical guidance.
Medicines for type 1 and type 2 diabetes
Insulin is essential for people with type 1 diabetes because their bodies cannot produce sufficient insulin.
Type 2 diabetes treatment is more varied. Depending on individual circumstances, treatment may include oral medicines, injectable glucose-lowering medicines, insulin, or combinations of therapies. Current diabetes standards emphasize individualized treatment rather than assuming everyone with type 2 diabetes should receive the same drug.
Medication selection can depend on glucose levels, cardiovascular or kidney disease, body weight, risk of low blood sugar, side effects, other medical conditions, treatment burden and individual preferences.
Blood-glucose monitoring
Monitoring helps show how glucose responds to food, activity, illness and treatment. Some people use finger-stick blood-glucose meters, while others use continuous glucose monitoring (CGM).
The American Diabetes Association 2026 Standards for glucose monitoring and treatment goals emphasize that monitoring requirements and glucose targets should be individualized. CGM has become a standard monitoring method for most people with type 1 diabetes and many people with type 2 diabetes who use insulin.
For many nonpregnant adults, an HbA1c below 7% is a commonly used general goal, but the 2026 ADA Standards explicitly recommend individualizing this target according to health, function, hypoglycaemia risk, treatment burden and other circumstances.
Area | What it involves | Why it matters |
Glucose management | Appropriate medicines, food choices, activity and monitoring | Reduces prolonged high glucose while avoiding unsafe lows |
Nutrition | Individualized balanced eating pattern | Supports glucose, weight and cardiovascular health |
Physical activity | Regular movement and structured exercise where appropriate | Supports insulin sensitivity, cardiovascular health and physical function |
Blood pressure and cholesterol | Monitoring and treatment when necessary | Helps reduce cardiovascular and kidney risk |
Eye care | Recommended retinal screening | Helps detect diabetic eye disease before major vision loss |
Kidney care | Kidney-function and urine testing as appropriate | Helps identify diabetic kidney disease |
Foot and nerve care | Foot checks and assessment for neuropathy | Helps prevent ulcers, infections and avoidable complications |
Education and follow-up | Diabetes self-management support and regular clinical reviews | Helps adapt treatment as health and needs change |
What Health Problems Can Diabetes Cause?
Diabetes can damage large and small blood vessels as well as nerves, particularly when glucose and other cardiovascular risk factors remain poorly controlled for long periods. Complications can involve the heart, brain, kidneys, eyes, nerves and feet.
Heart disease and stroke
Diabetes increases cardiovascular risk. Good diabetes care therefore includes attention not only to glucose but also to blood pressure, cholesterol, smoking, weight and other cardiovascular risk factors.
This is why modern diabetes management is broader than simply trying to produce a good HbA1c number.
Kidney disease
Diabetes can damage the kidneys' filtering structures over time. Kidney disease may initially produce no obvious symptoms, making appropriate blood and urine testing important.
Early identification can allow treatment to be adjusted to help protect kidney function.
Eye disease
High glucose can damage small blood vessels in the retina, the light-sensitive tissue at the back of the eye. Diabetes also increases the risk of other eye problems.
Regular eye examinations can detect diabetic retinal disease before the person notices major vision changes.
Nerve and foot problems
Diabetic neuropathy means nerve damage associated with diabetes. It can cause numbness, tingling, burning or pain, particularly in the feet and legs.
Loss of sensation can make a cut, blister or pressure injury harder to notice. Combined with circulation problems and impaired healing, this can increase the risk of foot ulcers, infections and, in severe cases, amputation. WHO identifies foot ulcers and lower-limb amputation among important potential diabetes complications.
When Can Diabetes Become an Emergency?
Diabetes can sometimes cause dangerous high or low glucose levels that require urgent treatment. Diabetic ketoacidosis (DKA) and hyperosmolar hyperglycaemic state (HHS) are potentially life-threatening emergencies associated with severe hyperglycaemia.
DKA is particularly associated with type 1 diabetes but can also occur in other circumstances. Possible warning signs include excessive thirst and urination, nausea, vomiting, abdominal pain, dehydration, rapid or deep breathing, marked weakness, confusion or reduced consciousness.
Seek urgent medical care when severe hyperglycaemia is accompanied by vomiting, breathing changes, significant dehydration, confusion, severe drowsiness or loss of consciousness.
What about dangerously low blood sugar?
Hypoglycaemia means blood glucose has fallen too low and is particularly relevant to people using insulin or certain glucose-lowering medicines.
The 2026 ADA Standards define glucose below 70 mg/dL (3.9 mmol/L) as clinically important hypoglycaemia. Symptoms can include sweating, shakiness, hunger, rapid heartbeat, irritability and confusion.
Severe hypoglycaemia can lead to seizures, unconsciousness or coma and requires immediate assistance. People at risk should receive individualized education about recognizing and treating low glucose and about when emergency help is necessary.
Conclusion
Understanding what is diabetes starts with understanding insulin and blood glucose. Type 1 diabetes results from autoimmune loss of insulin-producing cells, type 2 mainly involves insulin resistance and declining insulin production, while gestational diabetes develops during pregnancy. Symptoms can include thirst, frequent urination, tiredness, blurred vision and unexplained weight loss, although type 2 diabetes may initially cause none.
Diabetes is manageable with appropriate nutrition, activity, monitoring, medicines and regular screening for complications. Treatment goals should be individualized rather than copied from another person's plan. If you have symptoms or risk factors, ask a healthcare professional whether blood-glucose testing is appropriate; severe symptoms, confusion or breathing changes require urgent medical attention.
Frequently Asked Questions
1. What is the main cause of diabetes?
There is no single cause of all diabetes. Type 1 is an autoimmune condition, while type 2 develops through a combination of insulin resistance, genetics, ageing and other risk factors. Gestational diabetes occurs during pregnancy when normal glucose regulation becomes inadequate.
2. What are the first signs of diabetes?
Common signs include increased thirst, frequent urination, unusual hunger, tiredness, blurred vision and unexplained weight loss. Type 1 symptoms can develop rapidly, while type 2 may progress quietly for years. Symptoms alone cannot confirm diabetes, so appropriate blood testing is needed.
3. Can diabetes be cured completely?
There is currently no routine cure for type 1 diabetes. Some people with type 2 diabetes can achieve remission, meaning glucose remains below the diabetes range without glucose-lowering medication for a defined period. Remission is not the same as guaranteeing diabetes can never return.
4. Can eating too much sugar cause diabetes?
Sugar alone does not directly explain every case of diabetes. Type 1 is autoimmune, while type 2 develops through several interacting factors. Diets containing excessive energy and added sugars can contribute indirectly to type 2 diabetes risk, particularly through weight gain and metabolic health.
5. Can type 2 diabetes be prevented?
Type 2 diabetes can often be prevented or delayed, particularly in people at increased risk. WHO recommends regular physical activity, healthy eating, maintaining a healthy body weight and avoiding tobacco as important preventive measures. Type 1 diabetes currently has no established prevention strategy.
6. How often should someone with diabetes check blood sugar?
There is no single testing schedule for everyone with diabetes. Frequency depends on diabetes type, medication, insulin use, glucose stability and whether a meter or continuous glucose monitor is used. Current ADA guidance recommends tailoring monitoring to individual treatment needs and glucose goals.
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