A Clinical Overview of Insulin Pump Therapy for the Management of Diabetes: Past, Present, and Future of Intensive Therapy Cari Berget, Laurel H
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A Clinical Overview of Insulin Pump Therapy for the Management of Diabetes: Past, Present, and Future of Intensive Therapy Cari Berget, Laurel H. Messer, and Gregory P. Forlenza ■ IN BRIEF Insulin pump therapy is advancing rapidly. This article summarizes the variety of insulin pump technologies available to date and discusses important clinical considerations for each type of technology. ontinuous subcutaneous in- use an insulin pump (6) instead of a sulin infusion (CSII), more multiple daily injection (MDI) reg- Ccommonly referred to as insu- imen for intensive insulin therapy. lin pump therapy, is one of the most Additionally, the use of insulin pump notable advancements in diabetes therapy for individuals with type 2 technology in the past 50 years. The diabetes is increasing (7,8). first commercial insulin pumps were There are many advantages to on the market as early as the 1970s; using an insulin pump compared however, rapid uptake of insulin to an MDI regimen. Insulin pump pump technology did not occur until therapy allows for more precise and the early 2000s, after the conclusion flexible insulin dosing with fewer of the landmark Diabetes Control and injections. Many individuals with Complications Trial (DCCT) in the type 1 diabetes report using insulin early 1990s. The DCCT demonstrat- pumps because they want improved ed the importance of intensive insu- glycemic control and a more flexible lin therapy to maintain tight glycemic lifestyle than is afforded with MDI control and prevent diabetes compli- therapy, especially around meals and cations such as retinopathy, neuropa- social situations (9). Many studies thy, nephropathy, and cardiovascular and systematic reviews have demon- disease (1–4). strated improved glycemic control Since the conclusion of the DCCT, and a reduction in hypoglycemia insulin pump technology has ad- with insulin pump therapy compared vanced rapidly in an attempt to more to MDI in pediatric and adult popu- closely mimic physiologic insulin lations with type 1 diabetes (10–17). secretion and help patients achieve Although some randomized con- tight glycemic control while mini- trolled trials have shown no difference mizing the risk of hypoglycemia. As in glycemic control in young children University of Colorado, Denver, Barbara a result, use of insulin pumps has (<7 years of age) when comparing Davis Center for Childhood Diabetes, increased dramatically in the United insulin pump therapy to MDI (18,19), Aurora, CO States from <7,000 users in 1990 to parental satisfaction with insulin Corresponding author: Cari Berget, [email protected] nearly 100,000 users in 2000 (3) and pump therapy is high (20). Further, >350,000 users today (5). The major- insulin pumps offer many advantages https://doi.org/10.2337/ds18-0091 ity of insulin pump users have type 1 in managing unpredictable eating ©2019 by the American Diabetes Association. diabetes, although ~10% have type 2 habits and low insulin requirements Readers may use this article as long as the work is diabetes (5). According to the T1D in the youngest children (21), suggest- properly cited, the use is educational and not for profit, and the work is not altered. See www. Exchange registry, >60% of indi- ing that insulin pump therapy may be diabetesjournals.org/content/license for details. viduals within the T1D Exchange an ideal option for many young chil- 194 SPECTRUM.DIABETESJOURNALS.ORG BERGET ET AL . dren with type 1 diabetes and their families. Overall, insulin pump technology is evolving at an extraordinary rate, with new technologies becoming available every year. The integration of insulin pumps with continuous glucose monitoring (CGM) systems has drastically expanded the insulin pump market with “smarter” insu- lin pumps that suspend insulin for hypoglycemia or even automate some insulin delivery, all with the goal of helping individuals meet glycemic PRACTICE FROM RESEARCH TO targets with less burden (22,23). ■ FIGURE 1. Insulin pump with tubing. The tubing connects the insulin pump, However, this rapid technological which contains the reservoir where the insulin is held, to the infusion cannula progression can be overwhelming for inserted in the subcutaneous tissue. individuals with diabetes and their health care providers. Thus, the pur- poses of this article are 1) to provide an overview of insulin pump technol- ogies, from simple, disposable pumps designed for those with type 2 dia- betes to complex automated insulin delivery systems and 2) to discuss the clinical implications of these insulin pump technologies. Conventional Insulin Pump Therapy An insulin pump is a small, digital de- vice that continuously delivers rapid- acting insulin through a small catheter ■ FIGURE 2. Insulin pump without tubing (“patch pump”). Tubeless patch pumps inserted into the subcutaneous tissue contain the insulin reservoir and the infusion cannula and adhere directly to the skin. and secured in place on the skin with A handheld device is used to program insulin delivery and insert the infusion cannula. adhesive (referred to as an “infusion set” or “infusion cannula”). In most reservoir for up to 144 hours, but meals or high blood glucose correc- insulin pumps, the infusion set con- glulisine should be replaced every 48 tion (bolus). Basal insulin delivery nects to the pump by plastic tubing, hours due to a risk of crystallization. replaces the use of the longer-acting and insulin infuses from the pump Regular insulin is also FDA-approved exogenous insulin formulations used through the tubing to the infusion set for use in pumps and is sometimes in MDI regimens. A multitude of cannula and into the subcutaneous used instead of rapid-acting for- factors influence basal insulin needs, tissue (Figure 1). Some pumps, re- mulations because of its lower cost. including physiology, developmental ferred to as “patch pumps,” do not use Concentrated insulins (e.g., U200 or life stage (i.e., puberty or growth), tubing and instead adhere directly to U500), dilute insulin (e.g., U50 or activity level, time of day, and sleep the skin. Patch pumps deliver insulin U10), and ultra-rapid-acting insulin schedule. Insulin pumps deliver basal through the infusion cannula and are analogs (e.g., Fiasp) are undergoing insulin in increments as small as 0.01 programmed from a remote device us- studies but are not yet FDA-approved unit/hour and permit multiple rates ing wireless technology (Figure 2) (24). for use in pumps. of basal infusion throughout the day Insulin pumps generally use rapid- Insulin pumps deliver insulin in and night to best optimize glycemic acting insulin formulations (i.e., insu- two primary ways: a continuous control and individualize therapy, lin lispro, aspart, or glulisine). Lispro infusion of rapid-acting insulin mimicking nondiabetes physiology. and aspart are approved by the U.S. throughout the day and night (basal), Additionally, many insulin pumps Food and Drug Administration and discrete, one-time doses of rap- include a temporary basal feature, (FDA) for use in a pump insulin id-acting insulin given by the user for allowing users to temporarily increase VOLUME 32, NUMBER 3, SUMMER 2019 195 FROM RESEARCH TO PRACTICE / USING DATA TO IMPROVE DIABETES OUTCOMES or decrease basal delivery by a percent- therapy. These studies have reported units of bolus insulin delivery per day, age relative to the programmed basal a reduction in A1C of 1.0% or more in 2-unit increments. rate or by programming a new basal with lower total daily insulin require- Clinical studies using these novel rate. The temporary basal feature is ments, reduced risk of hypoglycemia, patch pumps for type 2 diabetes man- useful for situations in which insulin and higher treatment satisfaction agement have demonstrated improve needs may change drastically, but for a compared to MDI (25–28). These glycemic control, high patient satis- confined period, such as during acute benefits were obtained using relative- faction, reduced barriers to insulin illness or when exercising. ly simple insulin dosing regimens. pump treatment, and cost savings Users can program larger, discrete Participants required only one or two when compared to MDI therapy bolus doses of insulin for carbohy- basal rates, and use of the bolus cal- (32–34). drate consumption and high blood culator to determine bolus doses was Sensor Augmented Pump glucose corrections. Most insulin not associated with reduction in A1C Therapy (28). This result suggests that individ- pumps contain a bolus calculator with The development of CGM systems in uals with type 2 diabetes may not re- which the pump calculates a bolus the early 2000s was followed by the quire the complex pump features that dose recommendation based on the advent of the sensor augmented pump are beneficial for the management of current blood glucose value, current (SAP), which combines a CGM and type 1 diabetes (29) and that cited insulin on board (remaining active insulin pump in one system. A CGM barriers to conventional insulin pump insulin from previous bolus doses), device consists of three components: therapy for individuals with type 2 di- and total grams of carbohydrates that 1) a thin, flexible sensor, which is in- abetes, such as extensive educational the user enters into the pump. Some serted into the subcutaneous tissue requirements and high cost compared pumps have an extended bolus option, and continuously measures glucose to MDI, could be reduced with sim- which delivers a portion of the total levels in the interstitial fluid,2 ) a pler devices (30). bolus dose immediately and extends transmitter that sends the sensor glu- Thus, simplified pump technology the delivery of the remainder of the cose data to a receiver, and 3) a receiv- has been developed specifically target- dose over a longer period (usually er, which displays the glucose values. ing the needs of people with type 2 2–3 hours) to help prevent delayed In an SAP system, the insulin pump diabetes.