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[IP] Metabolic decompensation in pump users due to lispro insulin precipitation

Original article (problem with two pumpers and lispro/humalog)

answer from Minimed:

Bill Van Antwerp,
Chief Scientific Officer
Medtronic Minimed, Los Angeles, 91325

There are several questions that immediately become apparent after careful 
reading of your paper.

1. You claim that the deposit in the catheter in Case 1 was insulin based on 
immunoassy. How quantitatively did you do the analysis. In our hands 
catheter precipitations (we have looked at perhaps 500 removed catheters) is 
never comprised totally of insulin but also contains albumin and most of the 
times contains fibrin. Are you sure that there was nothing else in the 
deposit besides insulin? How did you dissolve the precipitate and did you 
estimate the mass of the deposit. You also claim that trouble shooting 
suggested that the catheter was occluded. What did you do and how and in 
what sequence? Did the pump show a no-delivery alarm? Was the catheter 
kinked? Could the deposit have formed post removal? This is often the case 
in our hands.

2. In case 2, there is no evidence that the catheter was occluded and 
insulin was seen on the outside of the catheter. Dithizone staining showed 
insulin on the outside. Is that surprising to you that a tube that was 
delivering insulin had insulin around it?

I believe your premise i.e. some patients have unpredictable blood glucose 
with lispro insulin, although from our investigations, it has nothing to do 
with precipitation but more to do with the subQ physiology.

I don't believe that there is any data that suggests insulin lispro is 
"unstable" in pump environments, after all more than 150,000 patients are 
using it very succesfully. Finally, I think that your conclusion that 
patient should switch insulin based on an N of 1 (case 1) is very premature 
and has caused significant worry in some fraction of the pump using 

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