Type 1 Diabetes

Type 1 diabetes (T1D), formerly known as juvenile diabetes or insulin-dependent diabetes, is an autoimmune condition in which the body's immune system destroys the insulin-producing beta cells in the pancreas. Insulin is essential for the regulation of blood glucose levels, and without it, blood sugar levels become dangerously high.

Signs and Symptoms

The onset of type 1 diabetes is often sudden and can develop at any age, although it is most common in children and adolescents. Key symptoms include frequent urination (polyuria), increased thirst (polydipsia), and significant weight loss.

Other symptoms may include increased hunger, blurred vision, fatigue, slow healing of wounds, bedwetting in children, irritability, and recurrent infections such as skin infections or candidiasis. In severe cases, untreated T1D can lead to diabetic ketoacidosis, characterised by fatigue, dry skin, abdominal pain, nausea, vomiting, confusion, and a fruity breath odour.

Causes

The exact cause of type 1 diabetes is unknown, but it involves a combination of genetic and environmental factors. The autoimmune destruction of beta cells results from an immune response targeting insulin-producing cells.

Genetic susceptibility plays a role, with certain HLA class II genes linked to increased risk. Environmental factors, such as viral infections, may trigger the autoimmune response, although the specific triggers remain unclear.

Additionally, some medications can induce diabetes by damaging beta cells or reducing insulin production.

Diagnosis

Diagnosis of type 1 diabetes involves testing blood glucose levels. The World Health Organisation defines diabetes as a fasting blood sugar level of 7.0 mmol/L (126 mg/dL) or higher, or a blood sugar level of 11.1 mmol/L (200 mg/dL) or higher two hours after an oral glucose tolerance test.

The American Diabetes Association also recommends diagnosing diabetes with glycated haemoglobin (HbA1C) levels of 48 mmol/mol (6.5%) or higher. To distinguish T1D from other types, blood tests for autoantibodies targeting beta cell components, such as glutamic acid decarboxylase (GAD65), are conducted.

Treatment

The cornerstone of type 1 diabetes management is insulin therapy. Insulin is administered through injections or an insulin pump to regulate blood glucose levels.

The goal is to maintain blood sugar within a normal range: 80–130 mg/dL before meals and less than 180 mg/dL after meals. Monitoring blood glucose levels is essential, often through capillary blood testing or continuous glucose monitoring.

Additionally, a diabetic diet and regular exercise are very important for managing the disease. Pramlintide, an amylin analogue, may be used to improve blood sugar control during meals.

In some cases, beta cell or pancreas transplants are considered.

Complications

If left untreated, type 1 diabetes can lead to severe complications such as diabetic ketoacidosis and hypoglycaemia. Long-term complications include cardiovascular disease, neuropathy, nephropathy, and retinopathy.

Poor blood sugar control increases the risk of infections, such as urinary tract infections and sexual dysfunction. People with T1D are also at higher risk for autoimmune disorders like thyroid diseases and celiac disease.

Epidemiology

Type 1 diabetes accounts for approximately 5-10% of all diabetes cases, affecting 11-22 million people globally. It is most commonly diagnosed in children and adolescents but can occur at any age.

The incidence varies widely by region, with the highest rates observed in Scandinavia and Kuwait. The prevalence is increasing worldwide, possibly due to environmental and lifestyle changes.

Research continues to look at the genetic and environmental factors contributing to type 1 diabetes, aiming to improve prevention, diagnosis, and treatment strategies for this lifelong condition.

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Self-assessment MCQs (single best answer)

Which of the following is a primary characteristic of type 1 diabetes?

What is the main treatment for type 1 diabetes?

Which symptom is commonly associated with the onset of type 1 diabetes?

Which test is used to distinguish type 1 diabetes from type 2 diabetes?

What is a major acute complication of untreated type 1 diabetes?

Which of the following is a long-term complication of type 1 diabetes?

Which environmental factor is believed to potentially trigger type 1 diabetes?

Which of the following is an essential component of managing type 1 diabetes?

In type 1 diabetes, what is the typical onset age range where it is most commonly diagnosed?

Which of the following autoimmune disorders is commonly associated with type 1 diabetes?