by Laura Dunkley

Created on: February 13, 2009   Last Updated: March 03, 2009

A flexible insulin regimen allows people with diabetes to adjust when and how much insulin is taken. With conventional insulin therapy, insulin is taken in prescribed doses at set times, e.g. 20 units insulin lispro with meals and 45 units insulin glargine at bedtime. A flexible regimen allows you to cover meals based on how much carbohydrates you are planning to eat. A flexible regimen also allows you to correct high blood glucose levels and to take less insulin if you are planning to exercise. A flexible insulin regimen gives you almost as much freedom as using the insulin pump. Changing to a flexible regimen is often a transition from conventional therapy to the pump.

A flexible regimen provides you with some benefits but there is some work involved. With meals you have to count carbohydrates and then calculate how much insulin you need based on your insulin-carbohydrate ratio (ICR). The ICR is the amount of insulin you need as a bolus to help metabolize the amount of carbohydrates you consume at a meal or snack. Your physician or diabetes educator will calculate your ICR. To calculate your ICR we use the 450/500 rule (450 for regular). For users of analog insulin divide 500 by your total daily dose (tdd) of insulin. If you are taking 30 units of Novolog and 20 insulin glargine, calculate 500/50=10 so your ICR is 1:10 and one unit of Novolog will cover 10 g Carbohydrates. If your meal has 60 g Carbohydrates, calculate 60/10=6 units. You would now give yourself 6 units of insulin This needs to be done for each carbohydrate containing meal or snack.

The next step in a flexible insulin regimen is correcting your high blood glucose levels by using the insulin sensitivity factor (ISF) which is using Novolog we use the 1800 rule. If using regular, the rule of 1500 applies. The formula is 1800/tdd, for the above patient 1800/50=36. Your ISF is 36 which is how many points in mg/dL one unit of insulin will lower your blood sugar. The second part of correcting your highs is knowing your target blood glucose which is 120 mg/dL. Calculate as follows: Actual BG (370)-Target (120)/ISF=# units needed. Calculate 370-120/36 =250/36=6.9 units insulin. You would now give administer 6.9 units. You can often round down to the nearest whole number. It is unlikely that you will need to round up. If your premeal blood sugar is 370, then calculate your correction and add to the number of units needed to cover your meal, in the above example, 6 units + 6.9 units=12.9 units. More often than not, taking 12 units in this patient would not be wrong as the patient likely still has what we would call insulin on board.

Now you know what a flexible insulin regimen is and can discuss it with your health care provider.

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