Diabetic Case Studies–The Insulin Rules in Action!

People come to jail taking the weirdest insulin regimens.  Often times, I don’t know whether these insulin schems are the result of a practitioner who does not understand insulin dosing well, or whether the patient “tinker” with their insulin dosing, themselves.  Here is a case from one my jails  (I have changed some of the data and patient characteristics to protect patient privacy).

English: C. H. Best and F. G. Banting ca. 1924

Banting and Best, Discoverers of insulin

A type 1 diabetic comes to jail taking Lantus 15 units in the morning and 40 units in the evening.  He says he takes his Humalog on a sliding scale, but when asked to define exactly what the parameters of his sliding scale are, it becomes apparent that he basically decides his Humalog dose based on gut-feeling.  He may take nothing; he may take up to 15 units.  He certainly has no concept of counting carbs.  He thinks his average Humalog dose is 6 units.  His admission HbA1C is 12.8, or an average blood sugar of over 300.  In other words, he is not doing a very good job of controlling his blood sugars on the outside.

Anyway, let’s apply the rules of insulin dosing to this patient:

Rule Number One:  What is his Total Daily Dose (TDD) of insulin?  He says he takes an average of 6 units of Humalog a dose, so 6 units times 3 meals = 18 units of Humalog.  Add that to 55 units of Lantus (15 in the morning, 40 at night) gives a Total Daily Dose of approximately 73 units of insulin a day.

Rule Number Two:  The TDD should be between 0.5-1.0 units per kilogram of body weight.  Since he weighs 92 kg, this is a reasonable TDD.

Rule Number 3:  Half of the TDD is Lantus; half is Humalog.  Half of 73 units is 36.5; we will round that down to 36 units of Lantus a day and we will give the other 36 units as Humalog.

Rule Number 4:  Humalog is split between the three meals of the day.  Since our dietitian has designed all three meals at our facility to have approximately the same number of carbs, we can divide the Humalog equally between the three meals, giving us 12 units of Humalog with each meal.

I’m not going to worry about rules 5-8 at this time.  I’m not a big believer in sliding scales–more on that later.

Rule Number 9:  About 20% of diabetics are fast-metaboloizers of Lantus, and do better with the Lantus dose split BID.  However, there is no benefit to splitting unevenly.  Where did this patient get this weird 15 in the morning, 40 in the evening split?  I’m not sure, but there is no advantage to doing this and it makes things more complicated.  If I do split his Lantus, I will split it evenly and give 18units twice a day.  It would be simpler just to give one dose.

So there is my new insulin dose for this patient:  Lantus 36 units once a day and Humalog 12 units with each meal.  I will watch his blood sugars and food consumption (especially commissary purchases) carefully for the next two or three days and then will make whatever adjustments I need.

My take on this patient is that he does not understand diabetic management very well.  Besides rectifying his insulin schedule, it will be important for us to educate him about how to take better care of himself once he gets out of jail.

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