Type 1 diabetes — insulin-dependent diabetes
Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease where the pancreas stops producing insulin — the hormone that moves glucose from blood into cells for energy.
Without insulin, blood sugar rises dangerously and the body breaks down fat for fuel, producing ketones — leading to diabetic ketoacidosis (DKA) if untreated.
Affects roughly 8% of people with diabetes in the UK — ~400,000 people — often diagnosed before age 40, peak in children and adolescents — but adult-onset type 1 is increasingly recognised.
Type 1 vs type 2
| Type 1 | Type 2 | |
|---|---|---|
| Cause | Autoimmune beta cell loss | Insulin resistance + deficiency |
| Onset | Often rapid, young | Gradual, older (usually) |
| Treatment | Insulin always | Lifestyle, tablets, sometimes insulin |
| Preventable | No | Often with lifestyle |
| Weight | Often weight loss at diagnosis | Often overweight |
See type 2 diabetes for comparison.
Symptoms — the 4 Ts
- Thirsty — unquenchable
- Toilet — frequent urination, bedwetting in children
- Tired — profound fatigue
- Thinner — weight loss despite eating
Also:
- blurred vision
- thrush — genital recurrent
- slow wound healing
- fruity breath — late, with ketones
Onset: days to weeks — not years like type 2.
Diagnosis
- random or fasting glucose very high
- HbA1c — may be normal early in rapid onset
- ketones in blood or urine
- autoantibodies — GAD, IA-2, ZnT8 — confirm type 1 vs type 2
- C-peptide low — no endogenous insulin
Same-day referral to diabetes specialist team if suspected.
DKA — emergency
Signs:
- blood glucose often very high (>11 mmol/L with symptoms)
- ketones positive
- vomiting, abdominal pain
- Kussmaul breathing — deep rapid breaths
- dehydration, confusion, collapse
Phone 999 — IV insulin, fluids, potassium monitoring in hospital.
Treatment — lifelong insulin
No oral alternative — insulin essential for survival.
Insulin regimens
- multiple daily injections — basal (long-acting) + bolus (rapid) with meals
- insulin pump — continuous subcutaneous infusion — NHS for selected patients
- hybrid closed loop — pump + sensor automates adjustments — expanding access
Blood glucose monitoring
- finger-prick testing
- continuous glucose monitors (CGM) — Libre, Dexcom — increasingly NHS-funded
- target ranges individualised — avoid hypoglycaemia
Carbohydrate counting
Match insulin dose to food — structured education (DAFNE, BERTIE) — NHS programmes.
Hypoglycaemia (hypos)
Blood glucose <4 mmol/L:
- shaking, sweating, hunger
- confusion, irritability
- treatment: 15g fast glucose — recheck 15 min
- severe: glucagon pen, 999 if unconscious
Driving: DVLA rules — report hypos requiring assistance.
Long-term complications (preventable)
Same as type 2 — from prolonged high glucose:
- retinopathy — eye screening annual
- nephropathy — urine albumin, ACE inhibitors if microalbuminuria
- neuropathy — foot checks
- cardiovascular disease
Tight control from early years reduces risk — without hypoglycaemia excess.
Living with type 1
- Diabetes UK — support, tech access campaigns
- sick day rules — never stop insulin — may need more
- alcohol — hypo risk
- exercise — adjust insulin/ carbs
- pregnancy — preconception planning — tight control essential
Research horizon
- immunotherapy trials to delay onset in at-risk relatives
- islet transplantation
- stem cell-derived beta cells
Not yet standard care — insulin remains lifesaving daily reality.
Child drinking constantly, wetting bed, losing weight — same-day GP — type 1 is urgent, treatable, manageable for life with specialist team support.
Common questions about type 1 diabetes
- What is the difference between type 1 and type 2 diabetes?
- Type 1 — autoimmune, no insulin production, usually young onset, requires insulin immediately. Type 2 — insulin resistance and relative deficiency, linked to obesity and age, treated with lifestyle and tablets first — may later need insulin. They are different diseases despite shared name.
- What causes type 1 diabetes?
- Autoimmune attack destroys pancreatic beta cells — exact trigger unknown; genetic susceptibility plus environmental triggers (viruses theorised). Not caused by eating sugar or obesity. Cannot be prevented currently.
- What are the symptoms of type 1 diabetes?
- Four Ts — thirsty (more than usual), toilet (urinating frequently), tired, thinner (weight loss despite eating). Also blurred vision, genital thrush, slow healing. Symptoms develop over weeks — DKA if untreated.
- What is diabetic ketoacidosis (DKA)?
- Medical emergency — insulin deficiency causes high blood sugar and ketone build-up — vomiting, abdominal pain, rapid deep breathing, fruity-smelling breath, confusion, dehydration. Phone 999 — needs IV insulin and fluids in hospital.
- Can type 1 diabetes be cured?
- No cure yet — lifelong insulin required. Islet cell transplantation and immunotherapy research ongoing. Artificial pancreas systems (closed loop) automate insulin delivery — improving quality of life on NHS for eligible patients.
- What is a hypo in type 1 diabetes?
- Hypoglycaemia — blood glucose below 4 mmol/L — shaky, sweaty, confused, irritable — treat immediately with 15g fast-acting glucose (Lucozade, glucose tablets), recheck in 15 minutes. Severe hypo — unconscious — glucagon injection or emergency services.
Sources
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