Letter: When clocks fall back, check insulin pumps


People in many countries around the world, and most states around the nation, will be setting their watches back one hour on Sunday. That is the end of this year’s daylight saving time. In the past this used to be an ordeal, as most clocks and watches had to be reset manually.

This hassle has lessened. Thanks to computer technology (automated clock resetting, etc.), this ritual is now being done automatically: in cellphones, computers and many other electronic gadgets.

But the hassle of manual resetting has not completely gone away. And for those who use insulin pumps, harm may occur as a result of incorrect insulin doses. Despite all the technology we enjoy, none of the current insulin pumps for patient use is GPS-enabled or has built-in automated clocks. The patient has to manually set the time: on first use, changing batteries, etc. And, of course, the DST change has to be done manually.

So, where would such harm come from? Insulin pumps have a syringe full of insulin, and the pump delivers insulin in two forms via a catheter under the skin: basal delivery (small steady infusion round the clock) and bolus delivery (rapid larger amounts before meals). The patient controls both delivery formats by programming the pump, which has a small mini-computer inside. Insulin delivery is time-dependent. If the time is not set up correctly, incorrect dosing will occur.

This is potentially harmful if a significantly different amount is erroneously given (basal or bolus). This may result in low sugar (hypoglycemia) or high sugar (hyperglycemia). If either is severe, this can be quite dangerous to patients.

A related issue to the DST change is the a.m.-p.m. format setting. If time is not set up correctly, patients may receive doses intended for night use during the day or vice versa.

This topic is not addressed in diabetes guidelines, and many physicians are not aware of this potential problem related to the time change.

Dr. Saleh Aldasouqi, associate professor

Chief of Endocrinology

Michigan State University