Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.
Match insulin pharmacology and delivery to glucose patterns, titrate safely, and prevent hypoglycaemia, ketoacidosis, device and concentrated-insulin errors.
Insulin replacement has three jobs: basal suppression of hepatic glucose release, prandial coverage of carbohydrate and correction of unexpected hyperglycaemia. One preparation can serve more than one role in a mixed regimen, but its action profile must match meals and monitoring.
The central decision is which regimen the person can use safely while meeting their goals. Flexibility, dexterity, vision, cognition, work, food predictability, hypoglycaemia awareness, kidney function and access to trained carers matter as much as HbA1c.
Titration is pattern management. A single reading can reflect food, stress, sensor lag or injection error; at least several comparable days are usually needed unless an immediate low, ketosis or severe symptom requires urgent change.
Falling glucose overnight or between meals, recurrent fasting lows and a need to snack without hunger suggest basal dose exceeds background requirement, especially after weight or renal change.
Repeated fasting rise without bedtime carbohydrate, missed dose or overnight hypoglycaemia suggests inadequate basal coverage; check technique and timing before increasing.
Post-meal peaks followed by later lows can reflect bolus given too late, inaccurate carbohydrate estimation or an insulin whose action outlasts absorption rather than simply too little insulin.
Unexplained rising glucose and ketones in a pump user can progress quickly because only rapid-acting insulin is present. Inspect cannula, tubing, reservoir and infusion site and use the emergency backup plan.
Rubbery thickened injection areas, repeated comfortable sites and highly variable absorption indicate local tissue change. Moving suddenly to healthy skin can lower requirements and provoke hypoglycaemia.
Confusion, seizure, loss of consciousness or need for another person's help requires rescue treatment, emergency assessment when indicated and urgent regimen, awareness and driving review.
A new pen colour, unfamiliar concentration, missing meal dose or accidental rapid-acting injection instead of basal can cause prolonged harm; identify exact product and time immediately.
Timing and duration vary by product; avoid correction stacking, confirm dose during poor intake and keep basal insulin. Pump interruption can cause rapid ketosis.
Do not use for meal correction. Renal decline, weight loss or movement from lipohypertrophy may lower need; concentrated products require exact device and brand prescribing.
Has a pronounced peak and greater nocturnal hypoglycaemia potential in some people. Resuspend cloudy insulin correctly and align meals and monitoring with its profile.
Less flexible for variable food or shifts; omitted meals cause hypoglycaemia and independent component titration is impossible. Confirm the exact mix and timing.
When fasting is consistently in range but daytime HbA1c remains high, more basal is unlikely to solve meal excursions and may create nocturnal hypoglycaemia.
Insulin enters unpredictably from lipohypertrophy. The same numerical dose can act much more strongly after moving to healthy skin, so planned reduction and monitoring are prudent.
Most pumps deliver only rapid-acting insulin; an occlusion therefore removes basal delivery as well as bolus capacity, allowing ketones to rise within hours.
The pen displays units designed for that formulation. Syringe extraction or mental conversion introduces large errors and must never be normal practice.
With supply expected to end in December 2026, each user needs an alternative chosen for pregnancy, hypoglycaemia, timing and dose—not an automatic electronic switch.
Beta-cell decline is part of type 2 diabetes biology. Framing insulin as punishment delays effective therapy and increases catabolic and emergency presentations.
Increasing basal insulin to treat post-meal hyperglycaemia after fasting is already on target.
Writing U or IU instead of units on an insulin prescription.
Withdrawing concentrated insulin from a pen with a syringe.
Failing to inspect injection sites when glucose becomes highly variable.
Leaving a pump user without rapid access to backup injection insulin.
Switching insulin detemir unit for unit without current specialist or ABCD guidance.
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A person with type 2 diabetes uses a large bedtime basal insulin dose. Fasting glucose is repeatedly 3.5 to 4.0 mmol/L, but HbA1c remains high and post-evening-meal readings are elevated. What is the best principle?
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.
Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes
May be less effective after fasting or alcohol. Recovery requires carbohydrate, supervision and urgent review of insulin, awareness, renal function and driving.