Diabetes Mellitus

Diabetes mellitus is a chronic metabolic condition that occurs when the body cannot produce enough insulin, cannot use insulin effectively, or both. Insulin is a hormone that helps glucose move from the bloodstream into cells, where it is used for energy. When this process is impaired, blood glucose levels rise and, over time, persistently high blood sugar can damage blood vessels, nerves, the kidneys, eyes, and other organs.

Diabetes is one of the most common chronic diseases worldwide. Although type 1 diabetes, type 2 diabetes, and gestational diabetes have different causes and characteristics, all forms require appropriate monitoring and management. Recognizing diabetes symptoms, understanding risk factors, and receiving regular screening can help prevent complications and support long-term health.

What Is Diabetes Mellitus?

Diabetes mellitus develops when glucose remains in the bloodstream instead of entering cells efficiently. Normally, the pancreas produces insulin in response to an increase in blood glucose after eating. Insulin allows glucose to enter cells and helps maintain blood sugar within a healthy range.

There are several main types of diabetes:

• Type 1 diabetes is an autoimmune condition in which the immune system attacks the insulin-producing beta cells of the pancreas. As a result, the body produces little or no insulin, and people with type 1 diabetes need insulin therapy to survive.
• Type 2 diabetes occurs when the body becomes resistant to insulin and, over time, the pancreas may no longer produce enough insulin to compensate. It is the most common form of diabetes and is strongly associated with factors such as excess weight, physical inactivity, family history, and increasing age.
• Gestational diabetes develops during pregnancy in women who did not previously have diabetes. Hormonal changes during pregnancy can make the body more resistant to insulin. Gestational diabetes usually improves after delivery, but it increases the mother's future risk of developing type 2 diabetes.

Understanding the difference between type 1, type 2, and gestational diabetes is important because their causes, treatment approaches, and long-term management differ significantly.

What Causes Diabetes?

The answer to what causes diabetes depends on the type.

Type 1 diabetes results from an autoimmune reaction that destroys insulin-producing cells. Genetic and environmental factors may contribute to the development of the disease, although the exact trigger is not always known.

Type 2 diabetes develops through a combination of genetic, metabolic, and lifestyle factors. Being overweight, having a sedentary lifestyle, having a family history of diabetes, and increasing age can increase the risk.

Gestational diabetes is primarily associated with hormonal changes during pregnancy and increased insulin resistance. Women who are overweight, have a family history of diabetes, previously had gestational diabetes, or have had a baby with a high birth weight may have a higher risk.

Family History of Diabetes

Having a family history of diabetes can increase a person's risk of developing the condition, particularly type 2 diabetes. Genetic factors can influence how the body produces and uses insulin, while shared lifestyle habits within families may also contribute to risk. People with a close relative who has diabetes may benefit from regular blood glucose checks and diabetes screening, especially when other risk factors such as excess weight, high blood pressure, or physical inactivity are present.

Diabetes Symptoms

The symptoms of diabetes can vary depending on how high blood glucose levels are and how quickly they develop. Some people, particularly those with type 2 diabetes, may have no noticeable symptoms for years.

Type 1 Diabetes Symptoms

Type 1 diabetes symptoms typically develop suddenly, sometimes over a matter of weeks. The sharp decline in insulin production causes blood glucose to rise rapidly, leading to excessive thirst, frequent urination, increased hunger, unexplained weight loss, severe fatigue, blurred vision, and nausea or vomiting. In children and young adults, these changes may become noticeable particularly quickly.

In some cases, diabetic ketoacidosis is the first indication of type 1 diabetes. This serious complication can cause abdominal pain, vomiting, deep or rapid breathing, confusion, and dehydration and requires urgent medical treatment.

Type 2 Diabetes Symptoms

Type 2 diabetes symptoms are often much less obvious because insulin production usually declines gradually and the body may compensate for insulin resistance for a long time. Increased thirst and urination, fatigue, blurred vision, slow-healing wounds, recurrent infections, or unexplained changes in weight may eventually appear.

Numbness or tingling in the hands and feet can also develop as a result of nerve damage. Because type 2 diabetes may be present for years before symptoms become noticeable, some people are diagnosed during a routine blood test rather than because they feel unwell.

Gestational Diabetes Symptoms

Gestational diabetes symptoms are often absent, which is one of the main reasons routine testing is recommended during pregnancy. When blood glucose becomes elevated, some women may notice increased thirst, more frequent urination, unusual tiredness, or blurred vision.

These changes can easily be mistaken for normal effects of pregnancy, making symptoms alone unreliable for detecting the condition. Blood glucose testing during pregnancy helps identify gestational diabetes even when the mother feels completely well.

Normal and Diabetic Blood Sugar Levels

Blood glucose testing is an important part of diagnosing diabetes. Normal and diabetic blood sugar levels are generally interpreted using fasting glucose, HbA1c, or an oral glucose tolerance test.

For non-pregnant adults, a fasting blood glucose level below 100 mg/dL is generally considered normal, while 100–125 mg/dL may indicate prediabetes. A fasting level of 126 mg/dL or higher on appropriate testing may indicate diabetes. An HbA1c below 5.7% is generally considered normal, while 5.7–6.4% indicates prediabetes and 6.5% or higher may indicate diabetes.

A random blood glucose level of 200 mg/dL or higher may also support a diabetes diagnosis when accompanied by typical symptoms.

Individual test results should always be interpreted by a healthcare professional, as diagnosis may require repeat testing or additional investigations.

Diagnosing and Screening for Diabetes

Diabetes screening can identify abnormal blood glucose before significant symptoms develop. Screening may be particularly important for people who are overweight, have high blood pressure, have a family history of diabetes, or have other risk factors.

Common tests include:

• Fasting blood glucose
• HbA1c
• Oral glucose tolerance test
• Random blood glucose testing in appropriate circumstances

Pregnant women are routinely assessed for gestational diabetes at an appropriate stage of pregnancy, even when they have no symptoms.

A diabetes consultation allows a physician to assess blood glucose results alongside medical history, medications, weight, blood pressure, family history, and other risk factors. This assessment helps determine whether further testing or treatment is necessary.

Diabetes Treatment

The goals of diabetes treatment are to maintain blood glucose within an individualized target range, prevent complications, and support overall health.

Treatment depends on the type of diabetes and may include:

• Healthy eating
• Regular physical activity
• Blood glucose monitoring
• Oral medications
• Injectable medications
• Insulin therapy
• Weight management
• Treatment of associated conditions such as high blood pressure and high cholesterol

People with type 1 diabetes require insulin because their bodies cannot produce enough of the hormone. Insulin may be administered through injections or insulin delivery devices.

For type 2 diabetes, treatment may begin with lifestyle changes and medication. As the disease progresses, additional medications or insulin may become necessary.

Diabetes Medications

There are several types of diabetes medications, and the choice depends on blood glucose levels, kidney and heart health, weight, other medical conditions, and individual treatment goals.

Common medication groups include metformin, sulfonylureas, SGLT2 inhibitors, GLP-1 receptor agonists, DPP-4 inhibitors, and insulin.

Some newer medications can provide benefits beyond lowering blood glucose, including cardiovascular or kidney protection in appropriate patients. However, not every medication is suitable for every person. Treatment should therefore be selected and adjusted by a physician.

Diabetic Diet and Nutrition

A diabetic diet does not mean completely eliminating carbohydrates or following a highly restrictive eating plan. Instead, nutrition focuses on balanced meals, appropriate portions, and choosing foods that help maintain stable blood glucose.

A healthy diabetes eating plan may emphasize:

• Vegetables and high-fiber foods
• Whole grains
• Lean sources of protein
• Fish and healthy fats
• Whole fruits in appropriate portions
• Limited refined carbohydrates and added sugars
• Reduced intake of highly processed foods

Meal timing and carbohydrate distribution may also be important, particularly for people using insulin or certain medications.

For gestational diabetes, a personalized gestational diabetes diet can help maintain healthy blood glucose while ensuring that the mother and baby receive adequate nutrition. A dietitian or diabetes specialist can create an eating plan based on individual needs.

Can Diabetes Be Reversed?

Whether diabetes can be reversed depends on its type. Type 1 diabetes cannot currently be reversed, because the body's insulin-producing cells have been destroyed.

Type 2 diabetes is different. Some people can achieve type 2 diabetes remission, particularly after significant and sustained weight loss and lifestyle changes. Remission does not necessarily mean the condition has been permanently cured, and blood glucose can rise again if risk factors return.

For people with severe obesity and type 2 diabetes, metabolic or bariatric procedures may also be considered.

Metabolic and Bariatric Surgery in Diabetes Treatment

The term diabetes surgery may refer to metabolic or bariatric surgery used to treat type 2 diabetes in selected people with obesity. Procedures such as gastric bypass and sleeve gastrectomy can lead to substantial weight loss and may significantly improve blood glucose control.

These procedures can sometimes lead to diabetes remission and reduce the need for diabetes medications. However, surgery is not appropriate for everyone and requires comprehensive evaluation by a multidisciplinary team.

Surgery is not a replacement for insulin in people with type 1 diabetes.

Complications of Diabetes

Persistently elevated blood glucose can damage small and large blood vessels throughout the body. The complications of diabetes can develop gradually, particularly when blood glucose, blood pressure, and cholesterol are not adequately controlled.

Diabetic Nephropathy

Diabetic nephropathy is kidney damage caused by diabetes. High blood glucose can damage the small blood vessels that filter blood in the kidneys, potentially leading to chronic kidney disease and, in advanced cases, kidney failure.

Regular urine and blood tests can help detect kidney damage at an earlier stage.

Diabetic Neuropathy

Diabetic neuropathy occurs when prolonged high blood glucose damages nerves. It commonly affects the feet and legs, causing numbness, burning, tingling, or pain. Loss of sensation can make injuries difficult to notice.

Diabetic Retinopathy

Diabetic retinopathy affects the blood vessels of the retina and can progressively impair vision. Regular eye examinations can identify retinal changes before significant vision loss occurs.

Diabetic Foot

A diabetic foot develops when nerve damage and reduced blood circulation make the feet more vulnerable to wounds and infection. People with diabetes should examine their feet regularly and seek medical attention for cuts, blisters, color changes, swelling, or wounds that do not heal.

Diabetes and Stroke

Diabetes increases the risk of cardiovascular disease and stroke. Persistently high blood glucose can damage blood vessels, while diabetes is also frequently associated with high blood pressure and abnormal cholesterol levels.

Good blood glucose, blood pressure, and cholesterol control can help reduce the risk of diabetes and stroke.

Diabetic Ketoacidosis

Diabetic ketoacidosis (DKA) is a serious and potentially life-threatening complication that occurs when the body does not have enough insulin and begins breaking down fat rapidly, producing acidic substances called ketones.

DKA can cause excessive thirst, frequent urination, nausea, vomiting, abdominal pain, deep or rapid breathing, fruity-smelling breath, confusion, and severe dehydration. It requires immediate medical attention and is particularly common in type 1 diabetes, although it can also occur in some people with type 2 diabetes.

Diabetes Management and Prevention

Effective diabetes management involves more than controlling blood glucose. Regular monitoring of blood pressure, cholesterol, kidney function, eye health, and foot health is also important.

Lifestyle measures can include regular physical activity, maintaining a healthy weight, following an individualized diet, avoiding tobacco, getting adequate sleep, and taking medications as prescribed.

For people who do not have diabetes, the question of how to prevent diabetes is especially relevant for type 2 diabetes. Maintaining a healthy weight, exercising regularly, choosing a balanced diet, managing blood pressure and cholesterol, and  can substantially reduce the risk.

Gestational diabetes cannot always be prevented, but maintaining a healthy weight before pregnancy, staying physically active, and following appropriate prenatal care can help reduce risk.

Diabetes Treatment in Turkey at Medical Park

Medical Park provides comprehensive diabetes care through multidisciplinary teams that may include endocrinologists, internal medicine specialists, nutritionists, cardiologists, nephrologists, ophthalmologists, and other specialists when needed. Patients undergo individualized assessment to determine the type of diabetes, degree of blood glucose control, associated conditions, and risk of complications.

Treatment plans may include lifestyle and nutrition counseling, blood glucose monitoring, diabetes medications, insulin therapy, and management of diabetes-related complications. For selected patients with type 2 diabetes and obesity, metabolic surgery may also be evaluated as part of a comprehensive treatment plan.

International patients seeking diabetes treatment in Turkey can receive diagnostic evaluation, specialist consultation, treatment planning, and follow-up care through Medical Park's international patient services. A personalized approach helps address both blood glucose control and the wider health factors that influence long-term diabetes outcomes.