Type 1 diabetes is a lifelong autoimmune condition affecting around 400,000 people in the UK. Unlike type 2 diabetes, it is not caused by lifestyle factors — it occurs when the immune system destroys the insulin-producing beta cells in the pancreas, leaving the body unable to produce insulin at all. Without insulin, blood glucose rises to dangerous levels. Type 1 diabetes requires lifelong insulin therapy to survive and is managed with a combination of technology, education, and NHS specialist support.
Type 1 vs Type 2 Diabetes: Key Differences
| Type 1 Diabetes | Type 2 Diabetes | |
|---|---|---|
| Cause | Autoimmune destruction of beta cells | Insulin resistance + progressive beta cell failure |
| Insulin production | None (absolute deficiency) | Reduced or ineffective |
| Age of onset | Often childhood/adolescence, but any age | Usually over 40, increasingly younger |
| Body weight | Usually normal or thin at diagnosis | Often (not always) overweight |
| Lifestyle cause? | No | Partly — genetics + lifestyle |
| Insulin required? | Always | Not always |
| UK prevalence | ~400,000 | ~4.3 million |
Symptoms of Type 1 Diabetes
Type 1 diabetes typically develops rapidly — symptoms often appear over days to weeks. The classic symptoms are known as the “4 Ts”:
- Toilet — needing to urinate frequently, including waking at night (polyuria)
- Thirsty — extreme, unquenchable thirst (polydipsia) — drinking litres of water but still thirsty
- Tired — severe, unexplained exhaustion
- Thinner — unexplained weight loss, often rapid
Other symptoms include: blurred vision, recurrent thrush or genital itching, slow-healing wounds, fruity-smelling breath (a sign of ketones — potentially dangerous).
Type 1 diabetes is a medical emergency if left undiagnosed. If you or your child has these symptoms, see a GP urgently or go to A&E. Diabetic Ketoacidosis (DKA) — a life-threatening complication — can develop within hours in someone with undiagnosed Type 1.
Causes and Risk Factors
Type 1 diabetes is caused by an autoimmune response — the immune system mistakenly attacks and destroys the insulin-producing beta cells in the islets of Langerhans in the pancreas. The trigger for this autoimmune attack is not fully understood but likely involves a combination of:
- Genetic predisposition — HLA gene variants (HLA-DR3 and HLA-DR4) strongly increase risk. If one parent has Type 1, the child’s risk is 1–9%; if a sibling has it, risk is 3–6%
- Environmental triggers — viral infections (e.g., enteroviruses, rubella), gut microbiome changes, and possibly early dietary factors may trigger the autoimmune process in genetically susceptible individuals
Diabetic Ketoacidosis (DKA) — Emergency
DKA is a life-threatening complication of Type 1 diabetes that occurs when there is insufficient insulin. Without insulin, the body burns fat for fuel, producing ketones — acids that build up dangerously in the blood. DKA can occur in new, undiagnosed Type 1 diabetes, or in known Type 1 if insulin doses are missed or illness increases insulin requirements.
Call 999 or go to A&E immediately if someone with Type 1 diabetes has:
- Rapid, deep breathing (Kussmaul breathing)
- Fruity/acetone breath
- Abdominal pain, nausea, or vomiting
- Confusion or reduced consciousness
- Blood ketones above 3 mmol/L or urine ketones ++ or above
Managing Type 1 Diabetes: Insulin Therapy
All people with Type 1 diabetes must take insulin daily. There are two main approaches in the UK:
Multiple Daily Injections (MDI)
The most common regime in the UK. Uses a combination of:
- Long-acting (basal) insulin — e.g., insulin glargine (Lantus, Toujeo), insulin detemir (Levemir), insulin degludec (Tresiba); taken once or twice daily to provide background insulin
- Short-acting (bolus) insulin — e.g., NovoRapid (aspart), Humalog (lispro), Apidra (glulisine); taken with meals to handle carbohydrate intake
Insulin Pump Therapy (CSII)
A small device worn continuously that delivers rapid-acting insulin through a cannula under the skin. Delivers a continuous basal rate plus user-triggered boluses for meals. NICE recommends pump therapy for those who cannot achieve HbA1c targets despite optimised MDI, or who have problematic hypoglycaemia. The NHS increasingly funds pumps — eligibility criteria reviewed by diabetes teams.
Technology: CGM and Hybrid Closed Loop Systems
Continuous Glucose Monitoring (CGM)
CGM devices (Dexcom G6/G7, Medtronic Guardian, Abbott Libre 3) measure glucose continuously via a sensor on the skin, alerting users to rising or falling levels. The NHS now provides CGM to all people with Type 1 diabetes following NHS England policy changes (2023). Flash glucose monitoring (FreeStyle Libre) was the predecessor — also available on NHS prescription for Type 1.
Hybrid Closed Loop (“Artificial Pancreas”)
Hybrid closed loop systems combine a CGM with an insulin pump that automatically adjusts basal insulin delivery based on glucose readings — significantly reducing hypoglycaemia and improving HbA1c. NHS England announced in 2023–2024 that hybrid closed loop systems (e.g., CamAPS FX with Ypsopump, Omnipod 5, MiniMed 780G) would be rolled out across the NHS — a transformative development for Type 1 management.
HbA1c Target and Blood Glucose Management
HbA1c (glycated haemoglobin) reflects average blood glucose over the past 2–3 months. NICE recommends a target HbA1c of 48 mmol/mol (6.5%) for most adults with Type 1 — lower targets carry higher hypoglycaemia risk. Time-in-Range (TIR) is increasingly used alongside HbA1c; the target is 70%+ of time within 3.9–10 mmol/L.
Hypoglycaemia (Low Blood Sugar)
Hypoglycaemia (“hypo”) occurs when blood glucose falls below 4 mmol/L. Symptoms: sweating, shakiness, dizziness, hunger, confusion, palpitations. Treatment follows the 15-15 rule: take 15g of fast-acting carbohydrate (3–4 glucose tablets, 150ml of fruit juice, or 5 Jelly Babies), wait 15 minutes, recheck. If unable to swallow or unconscious — glucagon injection (GlucaGen or Baqsimi nasal powder) and call 999.
DAFNE and Structured Education
The NHS offers DAFNE (Dose Adjustment For Normal Eating) — a 5-day structured education programme for adults with Type 1 diabetes. DAFNE teaches carbohydrate counting and insulin dose adjustment, giving people the skills to achieve better control while living flexibly. Ask your diabetes team about accessing DAFNE — it consistently improves HbA1c and quality of life.
Long-Term Complications
Good glucose control dramatically reduces the risk of complications:
- Diabetic retinopathy — damage to blood vessels in the retina; leading cause of blindness in working-age adults; annual eye screening (retinal photography) on NHS
- Diabetic nephropathy — kidney disease; annual urine albumin testing recommended
- Diabetic neuropathy — nerve damage causing numbness/tingling in feet; annual foot check on NHS
- Cardiovascular disease — significantly increased risk; blood pressure and cholesterol management essential
Support and Resources
- JDRF UK (jdrf.org.uk) — leading Type 1 research and advocacy charity
- Diabetes UK (diabetes.org.uk) — helpline: 0345 123 2399; excellent self-management resources
- Disability Living Allowance/PIP — Type 1 diabetes may qualify for financial support
- Free prescriptions — all people with Type 1 diabetes are entitled to free NHS prescriptions
- Driving and DVLA — must inform DVLA; must check blood glucose before driving; glucose meter data may be required
This article is for informational purposes only and does not constitute medical advice. If you or your child may have Type 1 diabetes, seek urgent medical attention. For ongoing management, always work with your NHS diabetes team.
Related Health Guides on YourHealthXpert
Explore these related NHS-aligned health guides:
- Type 2 Diabetes — type 1 and type 2 diabetes share some complications but have very different causes and treatments
- Anxiety and Depression — people with type 1 diabetes have significantly higher rates of depression and diabetes distress
- Chronic Kidney Disease — diabetic nephropathy is a major complication of type 1 diabetes
- Osteoporosis — type 1 diabetes is associated with reduced bone density and increased fracture risk
- Thyroid Conditions — autoimmune thyroid disease is significantly more common in people with type 1 diabetes