This article is written live from the American Association of Clinical Endocrinologists (AACE) 2017 Annual Meeting in Austin, TX. MPR will be reporting news on the latest findings from leading experts in endocrinology. Check back for more news from AACE 2017.

At the AACE 2017 Annual Meeting, study authors from Creighton University Medical Center and Raritan Bay Medical Center presented a case regarding the compatibility of intravenous (IV) insulin with other drugs. 

In critically ill patients, insulin and vasopressors are “the most commonly used medications,” described lead author Shilpi Singh, MD, MPH. However, some vasopressors are incompatible with regular insulin if administered in the same IV line.

A 62-year-old woman with a history type 2 diabetes, hypertension, and dyslipidemia presented to the hospital after having received CPR for cardiac arrest. Upon evaluation, her labs indicated normal values for anion gap, bicarbonate, and serum beta-hydroxy butyrate, which ruled out diabetic ketoacidosis. 

She was hyperglycemic (serum glucose 578mg/dL) and was started on IV regular insulin as per intensive care unit (ICU) protocol and was also started on vasopressors for blood pressure support. 

Her insulin dose had been increased to >450U/hr but glucose levels were still ranging >500mg/dL, at which point an Endocrinology consult was called in. Her “plumbing [tubings and pumps] was checked first, which was functioning properly,” noted Dr. Singh. The patient had multiple IV drugs going through two central lines, including a right femoral central venous catheter and a right internal jugular central venous catheter.  The insulin drip was administered through the same right internal jugular line as norepinephrine and vasopressin.  

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An interaction check showed that norepinephrine is not compatible with insulin in the same line as it renders the insulin ineffective. The insulin drip was then ordered to be started in a separate peripheral line at 6U/hr as per protocol based on current glucose levels. After this change, her blood sugar stabilized at 14U/hr of insulin on the new drip. 

There is not much clinical data on compatibility of IV insulin with other drugs “although it has been established that insulin is incompatible with norepinephrine, dobutamine, dopamine, magnesium, phenytoin, methylprednisolone, and ranitidine.” These agents should not be administered through the same IV line as insulin. Studies have shown that infusion of norepinephrine (at pressor doses) can cause resistance to insulin. A previous study (Marangou et al) reported a reduction in insulin efficacy of 70% in patients receiving norepinephrine.

 Findings from this patient case highlight “the importance of monitoring drug-drug interactions, medication errors and adverse drug events especially in ICU settings where multiple drugs are being used at the same time,” concluded Dr. Singh.

For continuous endocrine news coverage from the AACE 2017 Annual Meeting, check back to MPR’s AACE page for the latest updates.