Diabetes mellitus is a common long-term health condition that affects how the body regulates blood glucose, commonly called blood sugar. Glucose is an important source of energy for the body’s cells, but blood glucose levels need to remain within a healthy range.

When blood sugar remains too high over time, it can gradually damage blood vessels, nerves, kidneys, eyes, and other organs. The good news is that diabetes can often be effectively managed through appropriate medical care, healthy eating, physical activity, monitoring, and medications when necessary.

This article explains what diabetes is, how blood sugar is normally controlled, what happens in diabetes, and the major types of diabetes.

What Is Diabetes?

Diabetes mellitus is a group of metabolic disorders characterized by persistently elevated blood glucose levels, known as hyperglycemia.

Normally, the body breaks down carbohydrates from food into glucose. Glucose enters the bloodstream and is transported to cells, where it can be used for energy.

The hormone insulin, produced by specialized cells in the pancreas called beta cells, helps glucose move from the bloodstream into many body cells.

In diabetes, this system does not work properly. The body may produce little or no insulin, the cells may not respond adequately to insulin, or both may occur.

As a result, glucose can accumulate in the bloodstream, causing blood sugar levels to rise.

Why Is Blood Sugar Important?

Glucose is one of the body’s major energy sources. The brain, muscles, and other tissues depend on a continuous supply of energy.

Blood glucose comes mainly from:

Carbohydrates in food
The liver’s storage and release of glucose
Production of glucose by the body when needed

The body therefore needs a system that can increase or decrease blood glucose according to its energy requirements.

How Is Blood Sugar Normally Controlled?

Blood glucose is controlled through a coordinated system involving the pancreas, liver, muscles, fat tissue, hormones, and nervous system.

Two important hormones involved in blood glucose regulation are insulin and glucagon.

1. Insulin Lowers Blood Glucose

After eating, carbohydrates are digested and glucose enters the bloodstream.

In response to increasing blood glucose, the pancreas releases insulin.

Insulin helps the body:

Move glucose from the blood into many cells
Store glucose as glycogen in the liver and muscles
Reduce the amount of glucose released by the liver
Promote storage of excess energy

These actions help blood glucose return toward its normal range after a meal.

2. Glucagon Raises Blood Glucose

When blood glucose becomes low, the pancreas releases another hormone called glucagon.

Glucagon signals the liver to release stored glucose into the bloodstream. It also supports the production of glucose when additional energy is needed.

Insulin and glucagon therefore work in opposite but complementary ways to help maintain blood glucose balance.

What Happens to Blood Sugar After Eating?

After a meal, carbohydrates are broken down into glucose and absorbed into the bloodstream.

The sequence is generally:

Food → Digestion → Glucose enters bloodstream → Blood glucose rises → Pancreas releases insulin → Cells take up glucose → Blood glucose falls toward normal

This process happens repeatedly throughout the day.

What Happens When Blood Sugar Is Too High?

When blood glucose remains elevated, the condition is called hyperglycemia.

Persistent hyperglycemia can gradually affect blood vessels and nerves and may contribute to complications involving:

Eyes
Kidneys
Nerves
Heart and blood vessels
Feet

This is why diabetes management is not simply about treating symptoms. Maintaining blood glucose within an appropriate range is an important part of reducing the risk of long-term complications.

What Causes Diabetes?

There is no single cause of all diabetes. The cause depends on the type.

Factors involved can include:

Autoimmune destruction of pancreatic beta cells
Insulin resistance
Genetic factors
Family history
Pregnancy-related hormonal changes
Certain medical conditions
Some medications
Lifestyle and environmental factors

It is important to understand that diabetes is a group of different conditions rather than one single disease.

Types of Diabetes

The major types of diabetes include:

Type 1 diabetes
Type 2 diabetes
Gestational diabetes
Other specific types of diabetes

1. Type 1 Diabetes

Type 1 diabetes is an autoimmune condition in which the body’s immune system attacks and destroys the insulin-producing beta cells of the pancreas.

As a result, the body produces little or no insulin.

People with type 1 diabetes therefore require insulin treatment to survive.

Type 1 diabetes can develop at any age, although it commonly begins during childhood or adolescence.

Symptoms of Type 1 Diabetes

Symptoms can develop relatively quickly and may include:

Frequent urination
Excessive thirst
Increased hunger
Unexplained weight loss
Fatigue
Blurred vision

When significant insulin deficiency develops, a person can develop diabetic ketoacidosis (DKA), which is a medical emergency.

2. Type 2 Diabetes

Type 2 diabetes is the most common form of diabetes.

It usually develops when the body’s cells become less responsive to insulin, a condition known as insulin resistance. Over time, the pancreas may also become unable to produce enough insulin to compensate for this resistance.

Type 2 diabetes can develop gradually, and some people may have it for years without obvious symptoms.

Risk Factors for Type 2 Diabetes

Risk factors include:

Family history of type 2 diabetes
Overweight or obesity
Physical inactivity
Increasing age
Previous gestational diabetes
Certain ethnic and genetic factors
High blood pressure and other metabolic risk factors

However, type 2 diabetes can occur in people who do not have all of these risk factors.

Symptoms of Type 2 Diabetes

Possible symptoms include:

Frequent urination
Increased thirst
Increased hunger
Fatigue
Blurred vision
Slow healing of wounds
Recurrent infections
Tingling or numbness in the hands or feet

Some people have no noticeable symptoms, which is why blood glucose testing can be important for people at increased risk.

3. Gestational Diabetes

Gestational diabetes mellitus (GDM) is diabetes diagnosed during pregnancy that was not clearly present before pregnancy.

Pregnancy causes hormonal changes that can increase insulin resistance. In some pregnant women, the pancreas cannot produce enough additional insulin to maintain normal blood glucose levels.

Gestational diabetes often develops during the second or third trimester.

It is important because high blood glucose during pregnancy can increase health risks for both the mother and baby.

Women who develop gestational diabetes may also have an increased risk of developing type 2 diabetes later in life.

4. Other Specific Types of Diabetes

Some forms of diabetes occur because of specific underlying causes.

These can include:

Monogenic Diabetes

Monogenic diabetes results from changes in a single gene that affects how the pancreas produces or responds to insulin.

Examples include MODY (maturity-onset diabetes of the young) and neonatal diabetes.

Diabetes Caused by Pancreatic Diseases

Diseases or damage affecting the pancreas can interfere with insulin production and lead to diabetes.

Examples include some cases associated with:

Chronic pancreatitis
Pancreatic surgery
Pancreatic cancer
Cystic fibrosis

Drug- or Chemical-Induced Diabetes

Certain medications or chemical exposures can contribute to diabetes in susceptible individuals.

The exact mechanism and risk depend on the medication and the individual’s circumstances.

What Is Insulin Resistance?

Insulin resistance occurs when cells do not respond effectively to insulin.

Imagine insulin as a signal that tells cells to take up glucose from the bloodstream. With insulin resistance, the signal becomes less effective.

The pancreas may initially compensate by producing more insulin.

Over time, however, the pancreas may struggle to maintain sufficient insulin production, resulting in rising blood glucose and eventually type 2 diabetes in some people.

Can Diabetes Be Prevented?

Not every type of diabetes can be prevented.

For example, there is currently no established way to prevent type 1 diabetes in the general population.

However, many cases of type 2 diabetes can be prevented or delayed, particularly among people at increased risk.

Helpful measures may include:

Maintaining a healthy body weight
Regular physical activity
Eating a balanced diet
Limiting excessive intake of highly processed foods and sugary drinks
Getting adequate sleep
Avoiding tobacco
Having regular health checks when appropriate

Prevention does not mean that a person is guaranteed never to develop diabetes. Genetics, age, medical conditions, and other factors also influence risk.

How Is Diabetes Diagnosed?

Diabetes is diagnosed using blood glucose tests and, in some cases, other laboratory investigations.

Common tests include:

Fasting Plasma Glucose

This test measures blood glucose after a period of fasting.

Random Plasma Glucose

Blood glucose can also be measured at any time of the day, particularly when a person has symptoms suggestive of diabetes.

Oral Glucose Tolerance Test

During an oral glucose tolerance test, blood glucose is measured before and after consuming a standardized glucose solution.

HbA1c

The HbA1c test provides an estimate of average blood glucose levels over approximately the previous 2–3 months.

It is commonly used for diagnosing and monitoring diabetes, although it is not appropriate for every person or every clinical situation.

A healthcare professional should interpret test results in context, and abnormal results may need confirmation depending on the circumstances.

What Are the Symptoms of Diabetes?

Common symptoms can include:

Increased thirst
Frequent urination
Increased hunger
Fatigue
Blurred vision
Unexplained weight changes
Slow-healing wounds
Recurrent infections
Tingling or numbness in the hands or feet

However, symptoms vary considerably.

Some people, particularly those with type 2 diabetes, may have few or no symptoms in the early stages.

Can a Person Have Diabetes Without Symptoms?

Yes.

Type 2 diabetes can develop gradually, and blood glucose may remain elevated for a long time before noticeable symptoms appear.

This is one reason screening may be recommended for people with certain risk factors.

Why Is Diabetes Management Important?

Good diabetes management aims to keep blood glucose within an individualized target range while also addressing other cardiovascular and metabolic risk factors.

Depending on the type of diabetes and the individual’s health, management may include:

Healthy eating
Regular physical activity
Blood glucose monitoring
Oral medications
Injectable medications
Insulin
Blood pressure management
Cholesterol management
Regular eye, kidney, and foot assessments

Treatment should be individualized by a qualified healthcare professional.

Diabetes Is More Than Just “High Sugar”

Diabetes is sometimes described simply as “too much sugar in the blood,” but the condition is more complex.

It involves problems with insulin production, insulin action, or both.

Understanding this distinction helps explain why different types of diabetes require different approaches to treatment.

For example, a person with type 1 diabetes has an absolute insulin deficiency and requires insulin, while type 2 diabetes usually involves insulin resistance combined with progressive impairment of insulin secretion.

Frequently Asked Questions About Diabetes

Is diabetes caused only by eating sugar?

No. Diabetes has multiple causes and risk factors.

Eating large amounts of sugary foods can contribute to excessive calorie intake and weight gain, which can increase the risk of type 2 diabetes, but diabetes is not simply caused by eating sugar.

Can thin people develop diabetes?

Yes. People who are not overweight can also develop diabetes.

Type 1 diabetes, for example, can occur regardless of body size. Type 2 diabetes can also occur in people who are not overweight, although excess body weight is an important risk factor.

Is diabetes contagious?

No. Diabetes is not an infectious disease and cannot be transmitted from one person to another through ordinary contact.

Can diabetes be cured?

Some forms of diabetes can enter remission under certain circumstances, but there is currently no universal cure for diabetes.

Type 1 diabetes requires lifelong insulin replacement. Type 2 diabetes can sometimes be put into remission, particularly when diagnosed early and managed effectively, but ongoing medical follow-up remains important.

Gestational diabetes often improves after delivery, but women who have had it remain at increased risk of developing type 2 diabetes later.

How often should blood sugar be tested?

The appropriate testing schedule depends on the person’s health, diabetes type, treatment, medications, and healthcare provider’s recommendations.

People without diabetes may need testing periodically based on their risk factors, while people with diabetes may require more frequent monitoring.

Final Takeaway

Diabetes is a group of conditions characterized by elevated blood glucose caused by problems with insulin production, insulin action, or both.

Normally, insulin and glucagon help maintain blood glucose balance. In diabetes, this regulation becomes impaired, allowing blood glucose to remain higher than normal.

The main types are type 1 diabetes, type 2 diabetes, and gestational diabetes, with several other specific forms caused by genetic conditions, pancreatic disease, medications, or other factors.

Early detection and appropriate management can help reduce the risk of diabetes-related complications. If you have symptoms of diabetes or risk factors for the condition, speak with a qualified healthcare professional about appropriate blood glucose testing.

Medically Reviewed

Reviewed for general medical accuracy by Omokos Diagnostics’ health content team.

This article is intended for general health education and should not replace consultation with a qualified healthcare professional.

Medical Disclaimer

The information provided in this article is for educational purposes only. It is not intended to diagnose, treat, cure, or prevent any disease. Do not start, stop, or change medication based solely on information contained in this article. If you have symptoms of diabetes or concerns about your blood glucose, consult a qualified healthcare professional.

References

American Diabetes Association. Standards of Care in Diabetes—2026.
World Health Organization. Diabetes.
International Diabetes Federation. IDF Diabetes Atlas.
National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes Overview.
Centers for Disease Control and Prevention. About Diabetes.