Diabetes: Types, Causes, Symptoms, and Prevention

Last updated: 22/7/2026

Diabetes occurs when blood glucose levels rise because the body does not produce enough insulin or cannot use it effectively.

Symptoms may begin with increased thirst, frequent urination, and fatigue. However, some people, particularly those with type 2 diabetes, may not notice clear signs for years.

Early diagnosis helps control blood glucose and reduces the risk of damage to the eyes, kidneys, nerves, and heart.

What Is Diabetes?

Diabetes is a group of chronic conditions that affect how the body uses glucose.

Glucose is an important source of energy. Insulin, a hormone produced by the pancreas, helps glucose move from the blood into the cells.

Blood glucose rises when:

• The pancreas does not produce insulin.
• The pancreas does not produce enough insulin.
• The cells do not respond to insulin normally.
• Insulin deficiency and insulin resistance occur together.

Mayo Clinic explains that prolonged high blood glucose can lead to serious health problems and that the underlying cause differs according to the type of diabetes.

What Are the Types of Diabetes?

The main types of diabetes are type 1 diabetes, type 2 diabetes, and gestational diabetes. Prediabetes is another important condition.

Type	What happens?	When does it usually develop?
Type 1 diabetes	The immune system attacks the insulin-producing cells in the pancreas	It may develop during childhood or adulthood
Type 2 diabetes	The body does not use insulin effectively or does not produce enough insulin	It is more common in adults but can occur at any age
Gestational diabetes	Blood glucose rises during pregnancy	During pregnancy
Prediabetes	Blood glucose is higher than normal but not high enough for a diabetes diagnosis	It may develop before type 2 diabetes

What Is the Difference Between Type 1 and Type 2 Diabetes?

Type 1 diabetes usually develops because of an immune reaction that damages the insulin-producing cells. People with this condition generally need insulin throughout their lives.

Type 2 diabetes usually begins with insulin resistance. The pancreas attempts to produce more insulin, but over time it may no longer be able to meet the body’s needs.

The main differences include:

• Type 1 symptoms may develop quickly.
• Type 2 symptoms may develop gradually.
• Type 1 diabetes is not usually associated with excess weight or physical inactivity.
• Type 2 diabetes is associated with genetic factors, lifestyle, and weight, although it can also affect people without obesity.
• There is currently no confirmed way to prevent type 1 diabetes.
• In many cases, type 2 diabetes can be delayed or its risk reduced.

Hamad Medical Corporation explains that type 2 diabetes develops when the body does not produce enough insulin or when its cells do not respond properly to insulin, a condition known as insulin resistance.

What Causes Diabetes?

The causes of diabetes differ according to the type. Diabetes is not caused by eating sweets alone.

Causes of Type 1 Diabetes

The exact cause is not fully understood. Genetic and environmental factors may trigger the immune system to attack the cells of the pancreas.

Type 1 diabetes is not caused by excess weight or physical inactivity, and it cannot be prevented through lifestyle changes.

Causes of Type 2 Diabetes

The causes of type 2 diabetes include insulin resistance combined with the pancreas being unable to produce enough insulin.

The risk may increase with:

• Excess weight, especially around the abdomen.
• Physical inactivity.
• A family history of diabetes.
• Prediabetes.
• A history of gestational diabetes.
• High blood pressure or abnormal blood lipid levels.
• Increasing age.
• Certain hormonal conditions and medications.

Causes of Gestational Diabetes

The placenta produces hormones that may reduce the body’s response to insulin. In some pregnant women, the pancreas may not be able to compensate for this resistance.

What Are the Symptoms of Diabetes?

Diabetes symptoms differ depending on how high blood glucose levels are and how quickly the condition develops.

Possible symptoms include:

• Persistent thirst.
• Frequent urination, particularly at night.
• Increased hunger.
• Fatigue and weakness.
• Unexplained weight loss.
• Blurred vision.
• Slow-healing wounds.
• Recurrent skin or gum infections.
• Numbness or tingling in the feet.
• Dry and itchy skin.

Some people with type 2 diabetes or prediabetes may not have noticeable symptoms. Therefore, the absence of symptoms does not rule out the condition.

Mayo Clinic states that type 1 symptoms may develop quickly, while type 2 diabetes and prediabetes may cause mild or unnoticeable symptoms.

When Should Blood Glucose Be Tested?

Testing may be recommended when possible symptoms appear or when a person has factors that increase the risk of diabetes.

A doctor may recommend testing in the presence of:

• Excess weight.
• A family history of diabetes.
• Previous gestational diabetes.
• High blood pressure.
• Abnormal cholesterol levels.
• Physical inactivity.
• Polycystic ovary syndrome.
• Previous results indicating prediabetes.

The Saudi Ministry of Health provides a tool that estimates the risk of prediabetes based on age, weight, family history, gestational diabetes, and other factors. This tool does not replace blood testing or a doctor’s diagnosis.

Common diagnostic tests include:

• Fasting blood glucose.
• HbA1c.
• Oral glucose tolerance test.
• Random blood glucose when clear symptoms are present.

Is Diabetes Dangerous?

Diabetes can be managed effectively when it is diagnosed early and the treatment plan is followed. However, prolonged high blood glucose may gradually damage blood vessels and nerves.

Possible diabetes complications include:

• Heart disease and stroke.
• Kidney disease.
• Nerve damage.
• Foot ulcers.
• Retinal problems and reduced vision.
• Slow wound healing.
• Increased risk of infection.
• Dental and gum problems.

Having diabetes does not mean these complications will inevitably occur. Monitoring blood glucose, blood pressure, and lipid levels, along with regular eye, kidney, and foot examinations, helps reduce the risk.

How Can Diabetes Be Prevented?

Type 1 diabetes cannot currently be prevented. However, preventing or delaying type 2 diabetes is possible for many people.

Important steps include:

1. Maintaining a healthy weight: Losing a modest amount of excess weight may improve insulin sensitivity.
2. Being physically active: Around 150 minutes of moderate-intensity activity per week is often recommended, depending on the person’s health.
3. Choosing a balanced diet: Focus on vegetables, whole grains, legumes, and suitable sources of protein.
4. Reducing sugary drinks: Replace them with water or unsweetened beverages.
5. Eating more fibre: Fibre-rich foods may support fullness and meal regulation.
6. Avoiding smoking: Smoking is associated with increased cardiovascular risk.
7. Maintaining regular sleep: Poor sleep may affect weight and the body’s response to insulin.
8. Undergoing screening: Early detection is important when risk factors are present.

The Egyptian Health Council recommends intensive lifestyle programmes for adults at high risk, including healthy eating, regular physical activity, and weight reduction when needed.

Hamad Medical Corporation explains that healthy eating, physical activity, and stopping smoking are among the most important steps for preventing the progression of prediabetes.

Do People With Diabetes Need a Special Diet?

Not all people with diabetes need the same meal plan. The appropriate approach depends on treatment, weight, activity level, and overall health.

The following principles may help:

• Distribute carbohydrates across meals.
• Choose whole grains instead of refined grains.
• Eat vegetables regularly.
• Reduce added sugars.
• Pay attention to portion sizes.
• Avoid skipping meals when using medicines that may lower blood glucose.
• Consult a dietitian if meal planning is difficult.

Carbohydrates should not be eliminated completely, and strict diets should not be followed without medical supervision.

When Do Symptoms Require Urgent Medical Care?

Seek urgent medical help if any of the following occur:

• Difficulty breathing.
• Repeated vomiting.
• Severe abdominal pain.
• Drowsiness or clear confusion.
• Fruity-smelling breath.
• Severe thirst and urination with rapid deterioration.
• Loss of consciousness.
• Signs of severe low blood glucose, such as sweating, shaking, and confusion.

These signs may indicate severe hyperglycaemia, diabetic ketoacidosis, or severe hypoglycaemia.

Conclusion

Diabetes differs according to its cause and how it develops. The condition may begin with clear symptoms or remain unnoticed for years. Blood glucose testing when risk factors are present supports early detection. Balanced nutrition, regular activity, and a healthy weight can also reduce the risk of type 2 diabetes. We recommend seeing a doctor if persistent thirst, frequent urination, or unexplained weight loss occurs.

References

• Saudi Ministry of Health
• Egyptian Health Council
• Hamad Medical Corporation
• Mayo Clinic
• NHS UK
• Cleveland Clinic

 

Medically reviewed by the Magrabi editorial team with the support of specialist doctors.

Disclaimer: This article is intended for health education only and is not a substitute for consultation with a specialist doctor