What causes diabetes? Diagnosis, prevention, and treatment

Overview: What is diabetes?

Diabetes is a condition characterized by high glucose or blood sugar levels. Someone with higher blood sugar levels than normal may have one of three main types of diabetes: Type 1 diabetes, Type 2 diabetes, or gestational diabetes. 

Type 1 diabetes is an autoimmune condition that usually develops in children and adolescents, while Type 2 diabetes is a progressive, usually preventable, condition that generally occurs in adults. Gestational diabetes is a type of diabetes that can occur in pregnant women. People with higher blood sugar levels than normal who are not diagnosed with diabetes may have prediabetes and be at an increased risk of Type 2 diabetes.

In people with diabetes, glucose accumulates in the bloodstream, leading to symptoms and other health problems. Symptoms of diabetes may include fatigue, blurry vision, dryness in the skin, excessive thirst or hunger, weight loss, and frequent urination, among others. Long-term complications of diabetes include kidney disease, eye problems, and nerve damage. 

For people with diabetes, there is no cure, but medications, insulin, and lifestyle changes, such as a low-carb diet and regular exercise, can help manage the disease.  

Related: Diabetes treatment and medications

What causes diabetes? Diagnosis, prevention, and treatment

Diabetes, also known as diabetes mellitus, is one of the most common health conditions, with around one million Americans diagnosed with diabetes each year. Diabetes can develop in virtually anyone, although, according to the American Diabetes Association (ADA), it is more prevalent in African Americans, Asian Americans, and Hispanics. 

As a common health condition, diabetes is treatable and often preventable through lifestyle changes and medication. The causes of diabetes may vary and involve different risk factors, including age, obesity, and family history. 

Continue reading to learn more about the causes of diabetes and possible ways to prevent or manage it. 

What causes diabetes?

Diabetes occurs when the pancreas can’t produce enough insulin or the body can’t use insulin properly to process glucose. Insulin is a hormone necessary to process glucose, a simple sugar that the body normally converts into energy. 

In people with Type 1 diabetes, the immune system attacks insulin-producing cells leading to little to no insulin production. In people with Type 2 diabetes, the cells of the body fail to respond well to insulin, a problem known as insulin resistance.

The exact causes of the different types of diabetes are unknown. However, certain factors, such as genetics, being overweight, and not engaging in regular exercise, may play a role in the development of the disease. That is why diabetes prevention is often based on keeping a healthy lifestyle with a proper diet and exercise plan. 

Risk factors for diabetes

The different types of diabetes may have various risk factors, including genetic and environmental factors. Some risk factors may be modifiable, while others can’t be controlled. 

Type 1 diabetes

• Family history of Type 1 diabetes, with an immediate family member, such as a parent or sibling, that has been diagnosed with Type 1 diabetes

• Younger age, as the peak age of diagnosis is around 13 or 14 years old

• Carrying certain genes that lead to an increased risk, such as HLA-DQA1, HLA-DQB1, and HLA-DRB1

• The risk of Type 1 diabetes may be higher in people who are farther north from the equator, according to some studies

• Certain infections caused by viruses, such as cytomegalovirus, rotavirus, and rubella, may be linked to an increased risk of Type 1 diabetes

Type 2 diabetes

• Family history of Type 2 diabetes with an immediate family member, such as a parent or sibling, that has been diagnosed with Type 2 diabetes 

• Older age, as Type 2 diabetes generally occurs after age 40

• A diagnosis of prediabetes leads to a high risk of Type 2 diabetes

• Being overweight or obese

• Sedentary lifestyle or lack of physical activity less than three times per week

• An unhealthy diet with highly processed carbohydrates, saturated fats, and trans fats

• Smoking tobacco and drinking alcohol

• Depression 

• High blood pressure 

• Abnormal cholesterol levels 

Gestational diabetes

• Family history of diabetes with an immediate family member, such as a parent or sibling, that has been diagnosed with diabetes 

• Women who are older than 25 years of age have a greater risk of gestational diabetes than younger women

• A diagnosis of prediabetes can cause a high risk of gestational diabetes

• Being overweight or obese

• A history of gestational diabetes during a previous pregnancy

Prediabetes

• Sedentary lifestyle

• Being overweight or obese

• Family history of diabetes

• Age over 35

• African Americans, Hispanics, American Indians, and Asian Americans have a higher risk of prediabetes

• Heavy alcohol consumption and smoking tobacco

How is diabetes diagnosed?

A healthcare provider will diagnose diabetes through a physical examination and complete medical history. They may ask about your family history of diabetes, lifestyle habits, and other risk factors for diabetes. A healthcare provider will also ask about any signs or symptoms being experienced as a result of high blood sugar levels. 

Certain tests are needed to confirm a diagnosis of diabetes. These tests include fasting or random blood glucose tests, oral glucose tolerance tests, and A1C tests. A diagnosis may depend on whether current blood sugar levels fall in or outside a specific test range. One or a combination of blood tests may be helpful in diagnosing diabetes. 

Is diabetes hereditary?

People may inherit an increased risk of developing diabetes. If you have parents or siblings with diabetes, you are more likely to develop the condition. Having certain gene mutations is a risk factor for diabetes, and these mutated genes may run in families. The genes that increase your risk for diabetes are those involved in insulin production or the ability to use insulin to process sugar. Still, not everyone with a family history of diabetes will develop the condition. 

Is diabetes curable?

Diabetes is not curable, but it is manageable. Treatment consists of maintaining normal blood sugar levels to reduce symptoms and the risk of complications. In some cases, it’s possible to reverse prediabetes and Type 2 diabetes. 

People with Type 1 diabetes are generally treated with insulin therapy and lifestyle changes, while people with Type 2 diabetes may be recommended oral diabetes medications, insulin injections, and healthy lifestyle choices. One of the most common drugs prescribed for diabetes is metformin. 

To stay healthy, both people with Type 1 diabetes or Type 2 diabetes may require:

• A low-carb diet

• Regular blood sugar monitoring

• Regular physical activity

Is diabetes serious? When to see a doctor

Although it is a common chronic disease, diabetes should be taken seriously, as high blood sugar levels in the bloodstream can lead to serious health problems, such as:

• Nerve damage in the legs or feet, which may cause numbness or pain

• Ulcers in the feet that may lead to an infection and require an amputation

• Skin and mouth conditions

• Damage in the blood vessels of the eye, which may lead to blindness

• Damage in the blood vessels of the kidney, leading to kidney disease or kidney failure

• Heart and blood vessel disease, which may lead to a heart attack or stroke

• Hearing problems

• Cognitive and mental problems

If you suspect that you have diabetes, or if you have a family history of diabetes or other risk factors for the disease, you should visit your healthcare provider. In some cases, you may be referred to an endocrinologist who specializes in glands and hormones. People with diabetes may also need to visit:

• A dietitian to help control blood sugar levels through a low-carb diet

• A cardiologist to help prevent or treat heart disease

• An ophthalmologist to prevent diabetic retinopathy, cataracts, glaucoma, or other eye diseases related to diabetes

People with diabetes need immediate medical attention if they have blood glucose levels higher than 250 mg/dL and show signs of diabetic ketoacidosis. This condition occurs when the body is unable to use sugar for energy and instead breaks down fat into certain acids called ketones, which can accumulate in the blood and the urine. This condition can lead to coma and death if untreated. Symptoms of diabetic ketoacidosis include:

• Sweet, fruity-scented breath

• Fatigue and weakness

• Dry skin and mouth

• Nausea and vomiting

• Shortness of breath or rapid breathing

• Blurry vision

• Headache

• Abdominal pain

Some people with diabetes may experience hypoglycemia or severely low blood sugar levels that may require medical attention. This is more frequent in people with diabetes that take insulin to control their condition. Hypoglycemia symptoms include:

• Shakiness

• Fast heartbeat

• Sweating

• Headache

• Dizziness

• Weakness

• Confusion

How to prevent diabetes

Diabetes prevention starts with maintaining a healthy lifestyle. Many risk factors for diabetes are controllable through healthy habits. As the risk factors for diabetes can also overlap with those of other health conditions, it can be beneficial for overall health to keep the following in mind:

• Maintaining a healthy weight, as obesity and being overweight can increase the risk of diabetes 

• Eating a balanced, healthy diet of lean proteins, fiber, and plenty of fruits and vegetables while cutting down on excess sodium, sugar, and processed foods

• Exercising regularly with at least 30 minutes of moderate-intensity aerobic exercise most days of the week 

• Limiting alcohol intake and quitting tobacco, as these habits may contribute to increased insulin resistance 

Unfortunately, some risk factors, such as a family history of diabetes, are not modifiable. However, by improving what’s in your control, you can lower your risk of diabetes. 

FAQs about diabetes causes

What are the causes of sugar diabetes?

People with diabetes are unable to produce enough insulin or respond well to insulin to process sugar. This leads to high blood sugar levels. Diabetes causes are not clear, but genetics, diet, and lifestyle may play a role in the development of the disease. 

What causes Type 2 diabetes?

Type 2 diabetes is the most common form of diabetes, and it may be linked to different risk factors, such as genetics, poor lifestyle choices, and obesity. People with this condition are unable to respond to the insulin produced in their bodies, leading to insulin resistance and high levels of sugar in the blood. 

How to prevent diabetes?

Diabetes prevention involves managing the risk factors of diabetes. Certain risk factors, such as a family history of diabetes, are uncontrollable and may increase the risk of diabetes. However, several risk factors can be controlled. For example, healthy eating, maintaining a healthy weight, and regularly exercising may help prevent diabetes.

What’s next? Additional resources for people with diabetes

Test and diagnostics

• Classification and diagnosis of diabetes: standards of medical care in diabetes (2018), American Diabetes Association (ADA)

Treatments

• Medication and treatments, American Diabetes Association (ADA)

Scientific studies and clinical trials

• Immune mediated diabetes due to PD 1 inhibitors, Mayo Clinic

• A study to better understand the role of the hormones glucagon and insulin in the progression of diabetes, Mayo Clinic

• Restoring insulin secretion study (RISE), George Washington University Biostatistics Center

More information on related health conditions

• Diabetic eye disease, American Academy of Ophthalmology (AAO)

• Diabetes and your heart, Centers of Disease Control and Prevention (CDC)