Synopsis
Maintain essential insulin, prevent dehydration and ketoacidosis during illness, and create a safe medicine, fasting and glucose plan for procedures and surgery.
- Illness usually raises insulin need through stress hormones, but vomiting, renal decline and poor intake can lower it; monitoring decides rather than a blanket dose rule.
- Never stop basal insulin in type 1 diabetes, even when not eating. Pump users must correct delivery failure quickly because they have no long-acting depot.
- Check glucose more frequently during illness and measure blood ketones in type 1 diabetes, SGLT2 use or symptoms of ketoacidosis.
Key red flags
Thirst, polyuria, nausea, abdominal pain, vomiting, deep breathing, ketone odour or drowsiness with rising blood ketones signals insulin deficiency and needs urgent escalation.
Investigation priorities
Guide insulin, carbohydrate and escalation during illness and fasting.
Management branches
Acute illness with preserved consciousness and ability to drink and monitor.
- Increase glucose checks and measure blood ketones when type 1, SGLT2 treatment, marked hyperglycaemia or DKA symptoms apply; document readings and correction doses.
- Continue basal insulin, take correction rapid insulin using the learned algorithm, maintain sugar-free fluids and use carbohydrate-containing fluids when unable to eat normally.
Key medicines
Subcutaneous basal insulinContinue at the sick-day or perioperative dose specified in the individual plan.
Rapid-acting correction insulinUse the written glucose and ketone algorithm with repeat monitoring at defined intervals.