What Do You Need to Know When Your Patient Uses an Insulin Pump?
Kim A. Carmichael, MD—Series Editor
Carmichael KA. What do you need to know when your patient uses an insulin pump? Consultant. 2018;58(1):20-21.
Q. In which patients is an insulin pump indicated?
A. With the increasing popularity of continuous subcutaneous insulin infusion therapy, it is likely that primary care providers will encounter patients wearing these devices. More than 400,000 persons with type 1 diabetes mellitus in the United States reportedly are on insulin pumps,1 and the number has been growing steadily. Despite the fact that most of these patients will be under the care of a diabetes specialist,2 this is not always the case, and so it is important for primary care providers to be familiar with the basic concepts involved.
Although most patients with insulin pumps have type 1 diabetes, many others have type 2 diabetes. Patients with insulin pumps should be willing and able to perform 4 or more self-tests per day; before starting insulin pump therapy, they also already should have been self-administering multiple insulin injections per day.2
Insulin pump therapy may be started for a variety of reasons that range from simple convenience to the presence of severe glucose-control problems such as recurrent hypoglycemia (with unawareness), the dawn phenomenon (abnormal early-morning hyperglycemia), extreme insulin sensitivity, pregnancy, or an irregular daily schedule such as that of shift workers.2 Some patients with needle phobia may be better able to use pumps to deliver insulin.
Insulin pump therapy is not for everyone, however. Users need to be motivated and able to manage the pump and, ideally, be adept with carbohydrate counting and making insulin adjustments for alterations in diet and activity.2
Q. What types of insulin pumps and systems are available?
A. Insulin pumps come in a variety of sizes, shapes, and formats.2 The market is continually changing, and device designs are continually being upgraded, so a detailed review of all available brands is not possible here.
Most pumps must be attached to infusion tubing, but some are available without it and instead are directly applied to the skin and controlled with electronic remote-control devices. Some pumps are smaller than others; different pumps have differing insulin storage capacity; some pumps deliver insulin faster than others; and many pumps have fashionable add-ons to make the units more attractive.
Pumps are equipped with several alarms to help with mealtime and correction bolus reminders, which may improve adherence to insulin therapy. Some pumps may be connected to continuous glucose-monitoring devices, which can provide real-time feedback for calculating insulin requirements for better glucose control, and even alert users of impending serious hypoglycemia or hyperglycemia.
One device has an “interrupt-suspend” feature that temporarily shuts off insulin delivery from the pump when the patient’s blood glucose level gets too low or is at risk of becoming too low. A recently available combination pump and glucose monitor device can make continuous automated adjustments in insulin delivery, requiring that the user only provide mealtime insulin dosing calculations.
Q. What basic concepts about insulin pump delivery should primary care providers know?
A. The basal rate delivers the insulin required for basic daily metabolic needs. In most cases, the basal rate does not change, except in patients who require temporary adjustments such as for exercise, surgical procedures, or airline travel.
Bolus insulin may be given manually or based on doses calculated by a pump’s internal computers. Although pumps differ, most deliver insulin doses in increments as low as 0.1 unit. The dose calculations are also affected by “active insulin time,” which is tailored to the type of insulin used, since the different insulin brands may have different durations of efficacy.
The carbohydrate ratio is inversely proportional to the insulin dose, so a lower number provides a greater amount. The carbohydrate ratio is programmed to dietary intake at all times of the day and night, although the calculations may change at different times. Pumps may have specialized mealtime functions that can be programmed to allow square-wave boluses, which deliver insulin gradually for a set period, or even dual-wave boluses, which deliver both immediate and delayed insulin. Generally, these functions are employed only by sophisticated pump users under the guidance of a diabetes specialist.
The sensitivity index is likewise inversely proportional to the insulin dose and is used to calculate the amount needed to correct for high glucose levels. As with the carbohydrate ratio, the sensitivity index may vary depending on the time of day.
Just like all persons with diabetes, pump users should carry medical alert identification and injectable glucagon for emergency treatment of hypoglycemia. Persons with insulin pumps also should have a backup basal/bolus insulin plan, with prescriptions, in the event of pump failure.
Q. What complications might arise among persons with diabetes and an insulin pump?
A. One of the most common complications of insulin pump therapy is the failure to deliver the required amount of insulin. Such failures could be related to a disruption of the subcutaneous catheter insertion (visible or invisible) or to machinery malfunction. At times, a patient’s inadvertent changes to the insulin pump’s settings could alter the basal rate or the insulin bolus delivery calculations. As with any complex diabetes treatment regimen, a risk of hypoglycemia or severe hyperglycemia exists, so frequent monitoring and attention to self-care are critically important.
Q. What should be done if a patient is admitted to the hospital with an insulin pump?
A. Persons with insulin pumps may continue using them on an inpatient basis under limited circumstances. It is important to be aware of hospital policies and procedures regarding insulin pump use, as well as to acknowledge the certification of the persons adjusting and regulating pumps.3 Almost all hospitalists will encounter patients with insulin pumps,1 and protocols have been developed for safe management. Patients need to be physiologically and mentally stable in order to self-manage their pumps.3 They must be willing to adhere to hospital regulations and to assist with proper documentation of dose administration.
Q. What should be done if a patient’s insulin pump therapy needs to be discontinued?
A. For patients with type 1 diabetes whose insulin pump must be discontinued, rapid and effective insulin administration schedules must be initiated in order to minimize the risk of severe hyperglycemia and diabetic ketoacidosis.4 A patient’s insulin backup plan should be used as a guide to assist in determining proper and safe insulin doses, with some adjustments as needed to reduce the risk of hypoglycemia.
Kim A. Carmichael, MD, is an associate professor of medicine in the Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, at Washington University School of Medicine in St Louis, Missouri. He discloses that he is on the speakers bureau for Janssen, which may be relevant to the content of this article.
- Colwell J. Patients with pumps: potentially difficult negotiations are just one of the issues that can arise. ACP Hospitalist. April 2014. https://acphospitalist.org/archives/2014/04/insulin-pumps.htm. Accessed December 11, 2017.
- Grunberger G, Abelseth JM, Bailey TS, et al. Consensus statement by the American Association of Clinical Endocrinologists/American College of Endocrinology Insulin Pump Management Task Force. Endocr Pract. 2014;20(5):463-489.
- Dalton MF, Klipfel L, Carmichael K. Safety issues: use of continuous subcutaneous insulin infusion (CSII) pumps in hospitalized patients. Hosp Pharm. 2006;41(10):956-969.
- Carmichael KA. What next when an insulin pump is stopped? Consultant. 2011;51(7):462-464.