O-Ring Leaks

A good seal between the O-rings and the reservoir wall is essential to preventing insulin from leaking out the back! As can be seen, when this seal is lost, insulin leaks and blood sugars rise. The top picture originated during a new pump start as a health provider carefully filled the reservoir. The second reservoir was removed from a patient’s pump who was experiencing high blood sugars due to insulin loss. No warning except highs!

Cause

When reservoirs sit in warehouses and pharmacies, the lubricant needed for tight seating of the O-rings pools at the bottom of the reservoir.

Solution

Lubricate the pump barrel before filling it. Move the plunger in a new reservoir by pushing it fully into the reservoir, turning the plunger inside the barrel twice to coat the O-rings with lubricant, and pulling the plunger to the back of the reservoir. Repeat this procedure a second time before finally pulling the plunger to the back of the reservoir in order to place air into the insulin bottle.
Do not squeeze the wall of the reservoir, but hold the reservoir at the hub when tightening, etc.
Use care in handling the reservoir, especially while inserting it into the pump.

Last Updated on December 19, 2019

Author

John Walsh, PA, CDTC

John Walsh, PA is a Physician Assistant and Diabetes Clinical Specialist with Advanced Metabolic Care and Research. He has provided clinical care for patients with diabetes for more than 30 years, including thousands of people on insulin pumps. He is the co-author of Pumping Insulin, now in its 6th edition, Using Insulin, STOP the Rollercoaster, and The Pocket Pancreas. President of the Diabetes Mall, he is also the webmaster of diabetesnet.com, a highly trafficked source of diabetes information and technology, and opensourcediabetes.org. John is a consultant and advisory board member for pharmaceutical and device corporations and a frequent speaker on diabetes, insulin pump therapy, bolus calculators, infusion set design, glucose management, and the future of smart pumps, meters, and continuous monitors. His recent research, published in the Journal of Diabetes Science and Technology, explores the dosing and behaviors that lead to successful glucose outcomes by pump wearers. John has worn nearly every insulin pump and CGM available and is a sub-investigator on numerous research studies on diabetes drugs and devices.

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