What to do if you think you missed your glargine insulin

Remember, the body must have insulin working 24 hours a day

Glargine (also known as Lantus® and Optisulin®) is a long acting insulin generally given in the evening, that provides the body with a continues supply of insulin. It lasts about 24 hours. If there is no glargine and you have not given rapid acting insulin (NovoRapid®)/Humalog®)) within the past 3–4 hours, it is likely that your body will make ketones and is at risk of developing life threatening diabetic ketoacidosis (DKA).

What to do if missed dose (assuming dose is usually given in the evening)

Have I given my glargine? – I can’t remember!

If you are unsure if you gave your glargine you’ll need to regularly check your BGLs overnight. Ketones will need to be checked if your BGL is over 15 mmol/L. Without glargine, your BGL will start to rise as your dinner rapid acting insulin runs out (generally 4–5 hours after meal). Ketones of 1.0mmol/L or higher with high BGLs would suggest your glargine is missed. If so, follow the advice below, and work out a plan to stop this happening again.

To avoid this in the future, it is a good idea to log your glargine dose in your continuous glucose monitoring (CGM) app, tick your record book once you have given your dose or use a white board to tick off.

Also set a phone reminder each day at your glargine time.

Missing a dose but remembering before bed time

• Give your regular glargine dose and return to normal routine time the next night
• Check ketones, and if ketones are 1.0mmol/L or higher, in addition to your glargine, give 10% of total daily dose (TDD) of insulin as rapid acting insulin i.e. NovoRapid®)/Humalog®) (dose explanation in box below). 

Missing a dose and not realising until the morning

1. Check blood glucose levels (BGL) and ketones

2. If ketones are less than 1.0mmol/L give four hourly rapid acting insulin (NovoRapid®)/Humalog®) throughout the day and eat approximately two serves/30 grams carbohydrate (CHO) with each injection (the total CHO intake will vary depending on age and normal meal size). Continue this until you give the evening dose of glargine

3. If ketones are 1.0 mmol/L or higher and associated with any change to conscious state, severe headache, abdominal pain or vomiting, give 10% of TDD rapid acting insulin immediately (see below) and seek urgent medical attention and call an ambulance by dialing 000. You might be in DKA.

4. If ketones are 1.0mmol/L or more at breakfast.

• Extra rapid acting (NovoRapid®)/Humalog®) is needed to clear ketones with breakfast. Add 10% of the TDD to the breakfast dose of NovoRapid®/Humalog®.
• Check BGL and ketones in two hours. Another 10% of TDD (rapid acting insulin) may be needed if ketones remain 1.0 mmol/L or higher and BGL is high.
• To get back on track to the usual glargine time, rapid acting insulin (NovoRapid®)/Humalog®) must be given every four hours with approximately 2 serves/30 grams of CHO. See the box below to work out how much NovoRapid®/Humalog® is needed.  

5. If ketones are 1.0mmol/L or more and breakfast will not be eaten.

• Give 10% of TDD as rapid acting insulin
• As soon as breakfast will be eaten and within at least 2 hours, give usual breakfast dose
• Check BGL and ketones in two hours. Another 10% of TDD (rapid acting insulin) may be needed if ketones remain 1.0 mmol/L or higher and BGL is high.
• Four hourly rapid acting dose must be given every four hours with approximately 2 serves/30 grams of carbohydrate. See the box below to work out how much NovoRapid®/Humalog® is needed. 

6. If you are unsure what to do after reading the above advice, contact your treating diabetes team.

Example

Missed glargine, realised in morning

Waking at 8am with high BGL and ketones after missing an evening dose of glargine:
BGL is 21.3 and ketone levels are 2.4
Extra insulin is needed

Regular doses:
Pre breakfast: 5 units rapid acting
Pre lunch: 8 units rapid acting
Pre dinner: 6 units rapid acting
Glargine 15 units at 8pm
Total Daily Dose (TDD) = 5 + 8 + 6 + 15 = 34 units insulin

Calculations

1. 10% of TDD is given as an additional rapid acting insulin (NovoRapid®/Humalog®)

• 10% of 34 = 3.4
  This is rounded to 3.5 units if using ½ unit pen or 3 units if using whole unit pens

2. Four hourly rapid acting dose calculation 

• To calculate the amount of rapid acting insulin to give four hourly – TDD and ÷ by 6
  E.g. TDD = 34
  34 ÷ 6 = 5.7. This is rounded to 5.5 units if using ½ unit pen or 6 units if using full unit pens

If well and willing to eat breakfast add 3.5 units to breakfast dose of 5 units = 8.5 units rapid acting insulin

• Check BGL and ketones in 2 hours. If ketones still 1.0 mmol/L or higher, another 10% TDD as rapid acting insulin and seek medical attention.
• Continue with four hourly rapid acting dose for remainder of day with approximately 2 serves/30 grams CHO until glargine is given again in the evening, In this example give rapid acting insulin at 12 noon, 4pm and 8pm. Give glargine at usual evening time.
• Resume usual insulin doses the following day. 

Please note: this is general advice and each child’s insulin plan will differ.

Key points

• Without insulin in the body, BGLs and ketones will rise. If glargine is missed, rapid acting insulin must be given every four hours until glargine insulin is recommenced.
• If there are any signs of DKA you must seek urgent medical care by dialing 000 for an ambulance. 
• Seek medical advice if you don’t know what to do. 

Updated October 2024