This problem appears to be more common with Teflon infusion sets, and is often encountered in golfers, tennis players, and active individuals. Blood sugars rise unexpectedly due to leakage of insulin along the Teflon tubing back to the skin. No warning is given except for high blood sugars! Occasionally, leakage of insulin out to the skin surface will be seen after a large bolus.
Teflon is inert and the tissue along side it may "heal" and harden, especially after being in place for a couple of days. Any bumping or movement of the infusion set on the skin loosens contact between the teflon and tissue, and opens a path for insulin to escape to the outside surface.
Infusion sets that have a flexible cotton base attached to the skin and that have a lower profile are less likely to be bumped or moved. Use a plastic sandwich, i.e., a piece of IV3000 or other adhesive material under the set and a second piece over the top of the set to reduce catching.
Another solution is to switch to a metal set like the 90 degree Rapids which are small, comfortable, and less prone to tunnelling.
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