Table of Contents
Types of insulin
- Rapid-acting (given at start of meal)
- Novorapid (Aspart)
- Humalog (Lispro)
- Apidra (Glulisine)
- Short-acting (given 30 minutes before a meal)
- Actrapid
- Humulin S
- Intermediate-acting (usually given once/twice daily or as part of mix)
- Humulin I
- Insulatard
- Insuman basal
- Long-acting (usually given once daily)
- Levemir (Detemir)
- Lantus (Glargine)
- Tresiba (Degludec) – ultra-long-acting
Normal values (mmol/L)
Non-diabetic (random) = 3.5-7.8
Type 1 diabetic = 4-9
Type 2 diabetic = 4-8.5
Hyperglycaemia = >11
Hypoglycaemia = <4
Mixtures (for twice daily pre-mixed regimens)
Intermediate + short (given 30 minutes before breakfast and dinner)
- Humulin M3 (30% short-acting)
- Insuman comb 15 or 25 or 50 (15/25/50% short-acting respectively)
Intermediate + rapid (given at start of breakfast and dinner)
- NovoMix 30 (30% rapid-acting)
- Humalog Mix 25 or 50 (25/50% rapid-acting respectively)
Regimens
- Basal bolus regimen (basal long-acting insulin given at night with rapid-acting insulin given before every meal):

- Twice daily pre-mixed regimen (mixed intermediate-acting and short-/rapid-acting insulin given twice daily, before breakfast and before dinner):

- Intermediate insulin once/twice daily may also be used in type 2 diabetes to supplement oral hypoglycaemics and aid glycaemic control in the day (OM), at night/in morning (ON) or both (BD)
Changes in insulin requirements
Increased requirement
- DKA/hyperosmolar hyperglycaemic state
- Sepsis
- Illness
- Steroids
- Pancreatitis
- Dehydration
Decreased requirement
- Reduced calorific intake
- Exercise
- Reduced renal function (may reduce drug excretion)
- Alcohol
Adjusting insulin regimeNs (in response to glucose levels)
- Review the capillary glucose monitoring chart and work out the pattern of variation in glucose levels in relation to meals (readings are usually taken before meals)
- Use common sense – if a patient is eating less, the insulin dose will need to be reduced; on the other hand, certain conditions may require it to be increased (see box)
- Adjusting a basal bolus regimen:
- Levels high/low before breakfast (or in night) → increase/decrease bedtime long-acting insulin
- Levels high/low before lunch or dinner or bed → increase/decrease rapid-acting insulin given with meal before
- Adjusting a twice daily pre-mixed/intermediate regimen:
- Levels high/low before bed and before breakfast → increase/decrease evening insulin
- Levels high/low before lunch and before evening meal → increase/decrease morning insulin
- Adjusting a once daily morning regimen:
- Levels high/low before lunch and evening meal → increase/decrease insulin
- Adjusting a once daily evening regimen:
- Levels high/low before breakfast → increase/decrease insulin
- Doses are usually adjusted by approximately 10% depending on how abnormal the glucose levels are. Capillary glucose levels must then be closely monitored and dose-adjusted as required (it’s partly trial and error).
- Remember, hypoglycaemia is more dangerous than hyperglycaemia
- If you cannot get on top of it, ask the diabetes team for help (insulin type may need changing)
Insulin pumps
- Insulin pumps continuously infuse a basal rate of rapid-/short-acting insulin subcutaneously
- The rate can be changed depending on requirements (e.g. during exercise, diet or capillary glucose level)
- A button is pressed to give an insulin bolus at the start of a meal
- If patients are nil by mouth, the pump should be set to continue basal rate insulin but no boluses should be given. (5% dextrose infusion can be given and their basal rate adjusted accordingly – they do not need a variable rate insulin infusion.)
Variable rate insulin infusion (formerly called ‘sliding scale’)
NB: This is different to a fixed rate insulin infusion, as used in DKA.
- Used for patients with diabetes who are nil by mouth, e.g. perioperatively
- The capillary glucose is checked 1-2 hourly and the rate of insulin infusion is modified according to a predetermined protocol
- Continuous IV fluids containing glucose must be given alongside to maintain patient glucose levels and hydration
- Starting a variable rate insulin infusion:
- Most hospitals have a variable rate insulin infusion chart which just needs a signature
- Continuous IV fluids also need prescribing as below
- If the patient is taking long-acting insulin, this should be continued throughout (but short-/rapid-acting insulin must be suspended)
- During a variable rate insulin infusion:
- Continuous IV fluids, for example:
- Surgical patients: 5% glucose/0.45% saline/0.15% KCl at 80ml/hour
- Medical patients: 5% glucose (1L with 20mmol KCl) at 100ml/hour (unless capillary glucose is >15mmol/L, in which case give 0.9% saline until it returns to <15mmol/L)
- Check plasma Na+ and K+ daily
- Re-sign the variable rate insulin infusion chart daily
- The protocol’s infusion rates can be modified if the patient is particularly insulin-resistant/sensitive
- Continuous IV fluids, for example:
- Stopping a variable rate insulin infusion: confirm patient is eating and drinking and ensure the patient has received their long-acting insulin. (If not, a proportionate dose should be given at least 1 hour before stopping.) Give their usual mixed/rapid-acting insulin with meal and wait 30 minutes before stopping the variable rate insulin infusion. Monitor capillary glucose QDS for at least 24 hours.
Insulin prescribing rules
- Use insulin prescription chart if available (write ‘insulin as per insulin prescription chart’ at relevant times on main chart)
- You must write ‘UNITS’ (do not abbreviate to ‘U’)
- Specify the brand name and indicate the device the patient uses (e.g. disposable pen, vial, pen cartridge)
- Write ‘pre-breakfast/lunch/dinner’ rather than times if the insulin must be taken before meals
- Ensure you corroborate their prescription if unsure of a dose – never estimate!