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Type 1 diabetes
Type 1 diabetes is autoimmune destruction of beta cells with antibodies (GAD65, IA-2, ZnT8) and a low C-peptide; treatment is basal-bolus insulin or a pump with continuous glucose monitoring, and basal insulin is never stopped — even when eating little.
Why it matters in the exam
The question presents a young person with thirst, polyuria and weight loss, sometimes already in DKA, or a lean adult "with type 2 diabetes" who does not respond to tablets — LADA. Antibody and C-peptide tests separate them. The candidate must know the principles of treatment: a total daily dose of about 0.4–1.0 units per kg, roughly half basal and the rest for meals by carbohydrate counting; continuous monitoring (CGM) is recommended for all, and an automated system ("artificial pancreas") for suitable patients. Targets: HbA1c below 7% for most patients, more than 70% of the time in the 70–180 mg/dL range and under 4% of the time below it.
Other themes: hypoglycaemia and hypoglycaemia unawareness — glucagon for everyone on insulin; "sick day rules" — continue basal insulin, check ketones and drink more; and the "honeymoon" after diagnosis, when the insulin need falls temporarily. Screening for associated disease: coeliac and thyroid at diagnosis and periodically; retinopathy and albuminuria from 5 years after diagnosis and then every year. SGLT2 inhibitors are not approved in type 1 diabetes because of the DKA risk. In pregnancy, very tight control is needed before conception.
Key points
- Antibodies and a low C-peptide; insulin at once.
- 0.4–1.0 units per kg a day, about half basal; CGM for all.
- HbA1c below 7%; time in range above 70%, below range under 4%.
- Never stop basal; glucagon for every patient.
- Coeliac and thyroid; retinopathy and albuminuria 5 years after diagnosis.
Summary table
| Topic | Finding / target | Action | Exam note |
|---|---|---|---|
| Diagnosis | Antibodies (GAD65, IA-2, ZnT8), low C-peptide | Insulin at once | LADA: a lean adult not responding to tablets |
| Insulin | 0.4–1.0 units per kg a day, about half basal | Basal-bolus or pump | Carbohydrate counting |
| Monitoring | CGM for all | Over 70% of the time within 70–180 mg/dL | Under 4% of the time below range |
| HbA1c target | Below 7% for most patients | Individualise | Looser with hypoglycaemia unawareness |
| Sick days | Fever, vomiting | Never stop basal; ketones and fluids | Risk of DKA |
| Screening | Coeliac and thyroid; retinopathy and albuminuria 5 years after diagnosis | Yearly tests | Glucagon for every patient |
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Sources
- American Diabetes Association Standards of Care in Diabetes, 2025 — Type 1 diabetes: diagnosis, insulin therapy, technology and screening for complications
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Diabetes Mellitus: Diagnosis, Classification, and Pathophysiology
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.