Insulin and plastic are not always happy campers together. If insulin crystallizes in plastic tubing, it is usually at the end of the infusion set. This can block insulin delivery and cause high blood sugars. When delivery stops, the pump will sound an occlusion alarm.


This usually occurs when the infusion set is left in one site too long. It appears to occur more often with Humalog insulin. Other causes could be low infusion rate, leaving the pump in suspend mode for lengthy periods, and bad insulin. Reuse of reservoirs and infusion sets increase the risk of clogging.

Replace the infusion sets every 2 to at most 4 days.


If a clog is suspected, remove the infusion set. After removal, give a 5 unit bolus. If insulin comes out easily, look for another cause for the high reading. If delivery is very slow or nonexistent, a clog is the problem. Replace with a new set.

Read Pumping Insulin for easy steps on how to succeed with your insulin pump.

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