Undetected hypoglycemia in a patient receiving TPN

A 58-year-old female was admitted to the hospital in a severely malnourished state. She was treated for Crohn's disease with total parental nutrition (TPN). The patient's blood glucose was monitored by point of care (POC) testing every 4h, and a specimen is also drawn daily for metabolic assessment. The POC blood glucose values were consistently much higher than the lab values. Humalog insulin (5 U) was given to the patient to decrease high blood glucose levels that developed following administration of TPN. The patient then became hypoglycemic as a result of this insulin treatment. POC glucose testing, performed every 4h, did not detect the iatrogenic hypoglycemia, while lab glucose results were not given close attention. The lab sample was always drawn 1-2h after insulin was given to the patient and resulted in a lower blood glucose value. In addition, the symptoms of hypoglycemia such as shaking and dizziness were masked by the patient's poor health status, supine position, and the continuously given TPN.

These findings highlighted the importance of the correct sampling time following insulin administration and the consideration of the lab results in addition to POC. The patient's insulin regimen was modified to prevent further hypoglycemic events.