What is type 1 diabetes?
Type 1 diabetes is a chronic autoimmune disease in which the immune system destroys the insulin-producing beta cells in the pancreas. Without sufficient insulin, blood sugar (glucose) cannot enter cells for energy and builds up in the bloodstream. Persistent high blood sugar damages organs and nerves, leading to the complications of diabetes.
Type 1 diabetes is less common than type 2, accounting for about 5–10% of all diabetes cases. It often appears in childhood or young adulthood but can develop at any age. Genetic predisposition and environmental triggers such as viral infections are believed to play a role.
Symptoms
- Excessive thirst
- Frequent urination
- Extreme hunger with weight loss
- Nausea and vomiting
- Blurred vision
- Severe fatigue
- Mood changes and irritability
- Bedwetting in children
Causes and risk factors
An autoimmune reaction destroys pancreatic islet cells over months or years before symptoms appear. Risk factors include:
- Family history of type 1 diabetes
- Certain genes
- Viral infections or other environmental triggers
- Age under 20
- White ethnicity
Diagnosis
When symptoms suggest type 1 diabetes, blood tests are performed:
- Random plasma glucose ≥ 200 mg/dL (11.1 mmol/L)
- Fasting plasma glucose ≥ 126 mg/dL (7.0 mmol/L) on two occasions
- Hemoglobin A1C ≥ 6.5% to assess chronic glucose control
- Autoantibody testing (e.g., GAD65, IA-2) to distinguish type 1 from type 2
Severe onset may present with diabetic ketoacidosis (DKA), marked by high ketones, fruity breath odor, deep breathing, and vomiting.
Treatment
Type 1 diabetes requires lifelong insulin replacement. Other key aspects of management include:
- Insulin regimens:
- Ultra–long-acting (e.g., degludec)
- Long-acting (e.g., glargine, detemir)
- Intermediate-acting (e.g., NPH)
- Rapid-acting (e.g., lispro, aspart, glulisine)
- Inhaled human insulin (e.g., Afrezza)
- Frequent blood glucose monitoring or continuous glucose monitoring
- Carbohydrate counting to adjust insulin doses
- Healthy diet and regular physical activity
- Periodic A1C testing (at least twice a year)
- Preparation for hypoglycemia treatment (fast-acting glucose, glucagon kit)
Complications
Poorly controlled blood sugar damages multiple organ systems over time:
- Cardiovascular disease (heart attack, stroke)
- Kidney disease
- Eye damage (retinopathy)
- Neuropathy (nerve damage)
- Foot problems and ulcers
- Dental disease
- Increased risk of infections
- Depression
Resources
- Centers for Disease Control and Prevention: What is Type 1 Diabetes?
https://www.cdc.gov/diabetes/basics/what-is-type-1-diabetes.html - National Institute of Diabetes and Digestive and Kidney Diseases: Type 1 Diabetes Overview
https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/type-1-diabetes#diagnose - American Diabetes Association: Understanding Type 1 Diabetes
https://diabetes.org/about-diabetes/type-1 - ElSayed NA et al. Classification and diagnosis of diabetes: Standards of Care in Diabetes—2023. Diabetes Care. 46(Suppl 1):S19–S40.