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Switching from IV insulin to subcutaneous insulin 101..

1. Calculate the total insulin requirement over the past 6-12 hours on a stable IV insulin dose

2. Extrapolate the value to 24 hours. Let's call this value 'X'

3. 80% of X is the total subcutaneous insulin dose. Assuming the patient has been NPO during the IV insulin phase, this will largely represent Basal insulin dose. So 0.8x is the total basal insulin dose

4. If you are using Glargine, initiate 0.8x units (See above tweet) of glargine atleast 2-3 hours before discontinuing the IV insulin. This is done to allow the Glargine effect to seep in the system and prevent rebound hyperglycemia

5. Assuming the patient will now start having oral intake, you need to additionally add short-acting insulin before meals. Start with 0.1 units/kg of short-acting insulin before the meals. You may then adjust the dose as needed.

6. A patient transitioning from NPO to oral will often not have full meals immediately. Hence a slightly lower mealtime insulin dose would be better than an overzealous mealtime insulin dose. We can always give additional correction doses of short-acting insulin if required.

Examples. Adult Patient with DKA - now resolved and we are planning to start oral intake and subcutaneous switch

The patient's insulin requirement over the past 12 hours was 25 units. Hence total 24 hours dose is 50 units. 80% of 40. Hence we will start the patient.

Start inj GLARGINE 40 units - 2-3 hours before discontinuing oral dose

Additional orders of inj ASAPRT (or any shorting analog of your choice. Assuming patient weight of 80 kg, 8 units before the three major meals

Let's say it is 10 am. My prescription would be

1. inj GLARGINE 40 units at 10 am
2. Discontinue Insulin infusion at 12 noon
3. inj ASPART 8 units before breakfast, lunch, and dinner
4. Checking for sugars - before meals and bedtime