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Type 2 diabetes: symptoms, causes, treatments, and prognosis

Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 8 minutes read

Type 2 diabetes is a chronic condition causing high blood sugar levels (glucose). Unlike type 1 diabetes, where the body doesn't produce insulin, type 2 diabetes occurs when the body becomes resistant to insulin or doesn't produce enough insulin to maintain normal blood sugar levels. According to the American Diabetes Association (ADA) almost 30 million people in the US have been diagnosed with diabetes, with approximately 90% of them having Type 2 diabetes.

This article aims to provide a comprehensive overview of type 2 diabetes, including its risk factors, causes, symptoms, treatments, stages, differences from type 1 diabetes, prognosis, and when to seek medical attention. Diabetes represents a significant burden on the healthcare system in the US, with $413 billion in total costs in 2022. The majority of this expenditure is preventable.


The symptoms of type 2 diabetes may develop gradually and can be subtle, making them easy to overlook. Common symptoms include:

  • Increased Thirst and Urination: Excess sugar in the blood can cause increased thirst and urination.
  • Fatigue: Feeling tired and lethargic, especially after meals, is a common symptom of diabetes.
  • Blurred Vision: High blood sugar levels can affect the eyes' ability to focus, leading to blurred vision.
  • Slow Healing: Wounds and cuts may take longer to heal in individuals with diabetes.
  • Frequent Infections: People with diabetes are more prone to infections like urinary tract infections and skin infections.
  • Numbness or Tingling: Diabetes can cause nerve damage, leading to numbness or tingling in the hands and feet.

Causes and risk factors

Risk Factors

Several factors increase the risk of developing type 2 diabetes, including:

  • Obesity: Being overweight or obese is one of the most significant risk factors for type 2 diabetes. Excess body fat, particularly around the abdomen, increases insulin resistance.
  • Family History: A family history of diabetes increases the likelihood of developing the condition.
  • Lack of Physical Activity: Physical inactivity and a sedentary lifestyle contribute to insulin resistance and an increased risk of type 2 diabetes.
  • Poor Diet: A diet high in processed foods, sugar, and unhealthy fats and low in fruits, vegetables, and whole grains can increase the risk of diabetes.
  • Age: The risk of type 2 diabetes increases with age, particularly after age 45.
  • Ethnicity: Certain ethnic groups, including African Americans, Hispanic/Latino Americans, Native Americans, and Asian Americans, have a higher risk of developing type 2 diabetes.

Genetic Factors:

Genetics plays a significant role in the development of type 2 diabetes. Individuals with a family history of diabetes are at a higher risk of developing the condition themselves. While specific genes associated with type 2 diabetes have been identified, such as those involved in insulin production and glucose metabolism, the inheritance pattern is complex, involving multiple genes and interactions with environmental factors.

Insulin Resistance:

Insulin resistance is a fundamental mechanism underlying type 2 diabetes. Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels by facilitating glucose uptake into cells for energy. In individuals with insulin resistance, the cells in the body, particularly muscle, fat, and liver cells, become less responsive to the action of insulin. As a result, glucose remains in the bloodstream, leading to high blood sugar levels.

Several factors contribute to insulin resistance, including:

  • Obesity: Excess body fat, especially visceral fat around the abdomen, is strongly associated with insulin resistance. Adipose tissue releases adipokines, which can interfere with insulin signaling and promote inflammation.
  • Physical Inactivity: Lack of regular physical activity reduces the body's ability to utilize glucose effectively, contributing to insulin resistance.
  • Dyslipidemia: Abnormal levels of lipids (fats) in the blood, such as high triglycerides and low HDL cholesterol, are commonly seen in individuals with insulin resistance and type 2 diabetes.
  • Inflammation: Chronic low-grade inflammation in the body, often associated with obesity, can impair insulin signaling pathways and promote insulin resistance.

Impaired Insulin Production:

In addition to insulin resistance, impaired insulin production by the pancreas is another key factor in developing type 2 diabetes. Over time, the beta cells in the pancreas may become less efficient at producing insulin in response to elevated blood sugar levels. This can result from various factors, including:

  • Pancreatic Dysfunction: Damage to the pancreas due to inflammation, oxidative stress, or genetic predisposition can impair insulin production.
  • Beta Cell Dysfunction: Changes in the function and mass of insulin-producing beta cells within the pancreas can reduce insulin secretion in response to glucose.
  • Glucotoxicity and Lipotoxicity: Prolonged exposure to high levels of glucose and fatty acids can have toxic effects on pancreatic beta cells, contributing to their dysfunction and decline in insulin production.

Other Contributing Factors:

While insulin resistance and impaired insulin production are central to the development of type 2 diabetes, other factors may also play a role, including:

  • Hormonal Imbalances: Hormones such as cortisol, glucagon, and growth hormone can influence glucose metabolism and insulin sensitivity.
  • Gut Microbiota: Emerging research suggests that imbalances in the gut microbiota (microbial community in the intestines) may affect glucose metabolism and contribute to insulin resistance.
  • Environmental Factors: Environmental factors such as diet, stress, sleep patterns, and exposure to toxins may influence the risk of developing type 2 diabetes by affecting insulin sensitivity and pancreatic function.
  • Medications: Certain medications, such as corticosteroids, antipsychotics, and some anti-HIV drugs, can increase the risk of insulin resistance and diabetes.


The management of type 2 diabetes typically involves a combination of lifestyle modifications, medication, and monitoring. Treatment goals aim to control blood sugar levels, prevent complications, and improve overall health. Treatment options include:

  • Lifestyle Changes: Adopting a healthy diet, engaging in regular physical activity, maintaining a healthy weight, and quitting smoking can all have a positive impact on type 2 diabetes.
  • Medications: Oral medications such as metformin, sulfonylureas, meglitinides, and thiazolidinediones may be prescribed to help lower blood sugar levels. In some cases, insulin therapy may be necessary.
  • Blood Sugar Monitoring: Regular monitoring of blood sugar levels is essential to track progress and adjust treatment as needed.
  • Routine Medical Care: Regular check-ups with healthcare providers, including primary care physicians, endocrinologists, and diabetes educators, are essential for managing diabetes and preventing complications.

Stages of Type 2 Diabetes:


Prediabetes is characterized by blood sugar levels that are higher than normal but not yet high enough to be classified as type 2 diabetes. Individuals with prediabetes have impaired glucose tolerance, indicating a heightened risk of developing diabetes. Treatment for prediabetes typically involves lifestyle modifications, such as adopting a healthy diet, increasing physical activity, and achieving weight loss if overweight or obese. Medications like metformin may also be prescribed in some cases to reduce the risk of progression to diabetes.

Early Stage Type 2 Diabetes:

In the early stage of type 2 diabetes, blood sugar levels are consistently elevated, but symptoms may not be prominent or may be mild. This stage is often characterized by insulin resistance, where the body's cells become less responsive to insulin. Treatment for early-stage type 2 diabetes focuses on lifestyle changes to improve blood sugar control. This includes following a balanced diet, engaging in regular physical activity, monitoring blood glucose levels, and maintaining a healthy weight. Oral medications such as metformin, sulfonylureas, or DPP-4 inhibitors may be prescribed to help lower blood sugar levels.

Advanced Type 2 Diabetes:

In advanced type 2 diabetes, blood sugar levels are significantly elevated, and symptoms become more pronounced. Common symptoms include fatigue, increased thirst, frequent urination, blurred vision, and slow wound healing. At this stage, complications such as neuropathy (nerve damage), nephropathy (kidney disease), retinopathy (eye damage), and cardiovascular problems may also manifest. Treatment for advanced type 2 diabetes is multifaceted and aims to manage both blood sugar levels and complications. This may involve a combination of lifestyle modifications, oral medications, injectable insulin or other therapy, and management of comorbidities. Additionally, individuals with advanced type 2 diabetes may require regular monitoring and screening for complications, along with specialized care from healthcare professionals, including endocrinologists, ophthalmologists, and nephrologists.

Type 2 vs. Type 1 Diabetes:

While both type 1 and type 2 diabetes involve problems with insulin, they are distinct conditions with different causes and treatments. Type 1 diabetes is an autoimmune disorder where the body's immune system attacks and destroys insulin-producing cells in the pancreas. It typically develops in childhood or adolescence and requires lifelong insulin therapy. Type 2 diabetes, on the other hand, is often associated with lifestyle factors such as obesity and physical inactivity. It typically develops in adults but can also occur in children and adolescents. Treatment for type 2 diabetes may involve lifestyle modifications, oral medications, and sometimes insulin or other injectable therapy.


With proper management and adherence to treatment, many people with type 2 diabetes can lead healthy, fulfilling lives. However, uncontrolled diabetes can lead to severe complications such as heart disease, stroke, kidney disease, vision loss, and nerve damage. It is estimated that around 1 in 10 people aged over 40 in the US have Type 2 diabetes, and this number is increasing due to factors such as an ageing population and rising obesity rates. Early diagnosis, treatment, and ongoing monitoring are crucial for preventing complications and maintaining overall health.

When to See a Doctor

It's essential to see a doctor if you experience symptoms of diabetes, such as increased thirst, frequent urination, fatigue, or blurred vision. Additionally, if you have risk factors for diabetes, such as obesity, a family history of diabetes, or a sedentary lifestyle, it's essential to undergo regular screenings for diabetes.

What Your Doctor May Do

If you suspect you have diabetes or are at risk, your doctor may perform several tests to diagnose the condition, including:

  • Blood Sugar Tests: Fasting blood sugar tests, oral glucose tolerance tests, and hemoglobin A1c tests are commonly used to diagnose diabetes and monitor blood sugar levels over time.
  • Physical Examination: Your doctor will conduct a physical exam and review your medical history to assess your overall health and identify any signs or symptoms of diabetes.
  • Education and Counseling: Your doctor may provide education and counseling on lifestyle modifications, such as diet and exercise, to help manage diabetes effectively.
  • Medication Management: If you are diagnosed with diabetes, your doctor may prescribe medications to help lower your blood sugar levels and manage other risk factors, such as high blood pressure and high cholesterol.

In conclusion, type 2 diabetes is a common chronic condition that requires lifelong management. By understanding the risk factors, causes, symptoms, treatments, stages, and prognosis of type 2 diabetes, individuals can take proactive steps to prevent or manage the condition effectively. Early diagnosis, lifestyle modifications, medication, and regular medical care are key to successful diabetes management. If you suspect you have diabetes or are at risk, don't hesitate to consult with your healthcare provider for evaluation and guidance.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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