Type 1 diabetes (T1D)
Autoimmune destruction of pancreatic insulin-producing beta cells. Onset typically childhood / young adulthood but can present at any age. Lifelong insulin replacement is mandatory — this is not type 2 and oral agents alone do not treat it.
What it is
Type 1 diabetes is a chronic autoimmune disease in which T-lymphocytes infiltrate pancreatic islets and destroy insulin-producing beta cells. By the time symptoms appear, ~80–90% of beta-cell mass is lost. Without endogenous insulin, glucose can't enter most tissues, blood glucose rises, the body burns fat for energy producing ketones, and untreated patients progress to diabetic ketoacidosis (DKA). Onset is classically childhood or adolescence but adult-onset T1D (sometimes called LADA — latent autoimmune diabetes of adults) is common and frequently misdiagnosed as type 2. Diagnosis hinges on the combination of high glucose + low C-peptide ± positive autoantibodies (GAD, IA-2, ZnT8).
Key lab markers
- Fasting glucose — typically markedly elevated at diagnosis.
- HbA1c — usually >6.5% at diagnosis; useful for monitoring but not for diagnosing the type.
- C-peptide — LOW or undetectable; the cleanest marker that distinguishes T1D from T2D.
- Anti-GAD, IA-2, ZnT8 autoantibodies — confirms autoimmune mechanism.
- Ketones (urine or beta-hydroxybutyrate) — elevated in DKA.
Symptoms
- Polyuria (frequent urination, including overnight)
- Polydipsia (extreme thirst)
- Unintentional weight loss
- Fatigue, weakness
- Blurred vision
- Fruity breath, deep rapid breathing, abdominal pain (DKA — emergency)
- Recurrent infections (yeast, UTI)
When to discuss with a doctor
Polyuria + polydipsia + unintentional weight loss in any child or young adult warrants same-day glucose testing — this is the classical T1D presentation and DKA can develop within days. Adults with 'atypical type 2' (lean, family history of autoimmunity, poor response to oral agents) should have C-peptide + autoantibodies measured. Lifelong management is multidisciplinary endocrinology — basal-bolus insulin, continuous glucose monitoring, structured education. Mediora.AI flags the (low C-peptide + high glucose + high HbA1c) pattern; the autoimmune-vs-secondary decision is endocrinology.