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Insulin pseudo-resistance from adsorption to burettes


A postoperative diabetic patient, stabilized on 96 units/day Actrapid by syringe pump, when changed to a burette administration set required 1,200 units/day to achieve glycaemic control. The problem resolved when reverting to a syringe. An ex vivo experiment confirmed variable adsorption to syringes and burettes.


Postulating insulin adsorption to the infusion inline burette as the cause of this excessively high insulin requirement, we confirmed by an in vitro experiment with (a) a Terumo® syringe with B-Braun extension tubing and (b) a B-Braun Dosifix® inline burette system. Neutral insulin (Actrapid) with a concentration of 1 unit in 1 ml isotonic sodium chloride was run at 10 units/hour. The insulin concentration at the point of exit from the infusion system was analysed periodically (Table 1).

Table 1


Immediately after priming, there was approximately a 56% loss of insulin from the solution being delivered from the burette system, compared with 37% from the syringe system. This syringe–burette variability persisted throughout our study. At 9 hours, there had been an 81% loss of insulin from the burette system compared with 47% from the syringe. A second similar experiment also confirmed this observation.


Data on stability of insulin solutions and infusion systems are sparse. The insulin concentration is affected more when administered via inline burette infusion sets compared with syringe pump infusion lines [1]. When managing hyperglycaemia, apart from endogenous causes and true insulin resistance as reasons for escalating insulin requirements, insulin adsorption to the infusion systems should also be considered. More studies are required to elucidate this further.


  1. Corallo C, et al.: Aus J Hosp Pharm. 1995, 25: 129-135.

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Nagappan, R., Lingam, S., Corallo, C. et al. Insulin pseudo-resistance from adsorption to burettes. Crit Care 13 (Suppl 1), P117 (2009).

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  • Glycaemic Control
  • Insulin Concentration
  • Syringe Pump
  • Infusion System
  • Insulin Requirement