💉 Type 1 Diabetes Mellitus (T1DM) = autoimmune destruction of pancreatic ß-cells 🧬 → insulin deficiency → hyperglycaemia. Patients require lifelong insulin to prevent diabetic ketoacidosis (DKA ⚠️).

📖 About

Autoimmune destruction of ß-cells → insulin deficiency.
Daily physiological insulin production = ~16–24 units/day.
Insulin is essential for glucose + potassium uptake into cells.
Deficiency → hyperglycaemia, ketosis, DKA ⚠️.
Lifelong exogenous insulin required.

🧬 Aetiology

Autoimmune attack on islet ß-cells (HLA-DR3, HLA-DR4 association).
T-cell mediated destruction.
C-peptide = marker of endogenous insulin (low in T1DM).
Autoantibodies: GAD, ICA, IAA (useful in LADA diagnosis).

🩺 Clinical Presentation

Classic triad: Polyuria 🚽, polydipsia 💧, weight loss ⚖️.
Blurred vision 👁️, recurrent candidiasis 🍞.
DKA: ketotic breath, Kussmaul breathing, abdominal pain.

📊 Blood Glucose Ranges (UK vs US)

Range	UK (mmol/L)	US (mg/dL)
Normal (Fasting)	4.0 - 5.9	72 - 106
Normal (Post-meal)	4.0 - 7.8	72 - 140
Pre-diabetes (Fasting)	6.0 - 6.9	108 - 124
Diabetes (Fasting)	≥ 7.0	≥ 126
Hypoglycaemia	< 4.0	< 72
Diabetes (Random + symptoms)	≥ 11.1	≥ 200

⏳ Complications

Microvascular 🩸: Retinopathy, nephropathy, neuropathy.
Macrovascular ❤️: IHD, stroke, PVD.
Other: Foot ulcers 🦶, infections, cataracts, gastroparesis.
Psychological: Depression, anxiety.

🔎 Investigations

Islet autoantibodies: ICA (~80%), GAD (~90%).
Low/absent C-peptide.
HbA1c for monitoring control.
Baseline: FBC, U&E, lipid profile, ECG, retinal photography.

🛠️ Management

All require insulin 💉 (no role for oral monotherapy).
Lifestyle: diet, exercise, smoking cessation, weight management.
Education: sick day rules, carb counting, hypo awareness.
"Honeymoon period": temporary recovery of ß-cell function with lower insulin needs.

💉 Insulin Regimens

SC injections at rotating sites to prevent lipohypertrophy.
Twice-daily mixed insulin: Intermediate + soluble.
Basal-bolus: Long-acting basal (50–60%) + rapid-acting with meals (preferred).
Insulin pump: For patients with HbA1c >7.5% despite basal-bolus regimen.
Acute illness: Continue insulin (never stop), adjust doses; IV insulin if unable to eat or in DKA.

💡 Clinical Pearl: - T1DM = think young, lean, rapid onset. - Always exclude DKA if a patient presents unwell with polyuria/polydipsia + hyperglycaemia. - In exams: "Ketones + acidosis = Type 1 until proven otherwise."

📚 Case Example

👦 A 14-year-old boy presents with polyuria 🚽, weight loss ⚖️, and abdominal pain. On exam: Dehydrated, Kussmaul breathing, ketotic breath. Capillary glucose: 28 mmol/L, ketones positive, pH 7.1. ✅ Diagnosis: Diabetic ketoacidosis in new-onset Type 1 DM. 🛠️ Management: IV fluids, IV insulin, potassium monitoring, later long-term insulin regimen.

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Diabetes Mellitus Type 1