October 31, 2016
2 min read

Daylight saving time could lead to dose errors for insulin pump users

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As patients prepare to set their clocks back 1 hour for daylight saving time, many with diabetes may overlook a clock on one of their most important devices: their insulin pump.

For patients with diabetes on pump therapy, an incorrect pump clock setting could affect insulin delivery, resulting in potential errors that put patients at risk for hypoglycemia, hyperglycemia and diabetic ketoacidosis, said Saleh Aldasouqi, MD, FACE, ECNU, associate professor of medicine and chief of endocrinology at Michigan State University College of Human Medicine.

Saleh Aldasouqi
Saleh Aldasouqi

“The problem is all insulin pumps do not automatically adjust,” Aldasouqi told Endocrine Today. “Most clinicians are not looking at the clock on the insulin pumps of their patients. Before I became aware of this, I never did. For many patients, it may not be easy for them to look at the clock. The screen on the pump is small. So, unless you have an open eye, you may miss it.”

In a literature review published in the Journal of Diabetes Science and Technology in October 2014, Aldasouqi and Amy J. Reed, RD, CDE, of Sparrow Hospital in Lansing, Michigan, noted that a pump with an incorrectly set clock can particularly affect bolus insulin delivery when doses are programmed with bolus calculators.

“During the spring [daylight saving time] change, the lunch time will advance,” Aldasouqi and Reed wrote. “If the carb ratio time on the pump clock is not manually adjusted, the morning (1:10) carb ratio will be delivered at lunch, delivering a 33% bigger insulin dose (unless the patient picks up the glitch when the pump asks the patient to verify the final dose calculation).”

All insulin pump manufacturers include clock safety information in their instruction manuals. Medtronic, for example, reminds patients on its website to synchronize clocks on its computer, insulin pump and blood glucose meter to maintain time accuracy when uploading any data. However, Aldasouqi said more steps must be taken to make sure patients are reminded to make the proper clock adjustments.

“The first thing that the doctor should do is look at the clock of every patient with an insulin pump that they encounter,” Aldasouqi said. “Whenever we have a patient on pump therapy, we should tell them to make sure their pump is set to the correct time all the time, but especially after daylight saving time, whenever they change pump batteries, or when their pump jams or malfunctions.

“There are about six or seven brands of insulin pumps, and each one is different,” Aldasouqi said. “It’s like cellphones. Every pump comes with instructions that are different when it comes to the clock setting. So, each patient should be well educated to make sure the cock is always set up correctly.” by Regina Schaffer


Aldasouqi S, Reed AJ. J Diabetes Sci Technol. 2014;doi:10.1177/1932296814541811.

For more information:

Saleh Aldasouqi, MD, FACE, ECNU, can be reached at saleh.aldasouqi@hc.msu.edu.

Disclosure: Aldasouqi reports receiving speaking honoraria from Janssen, Sanofi and Takeda.