Insulin Pumping Patches: Emerging Insulin Delivery Systems

Abstract

In this special section of JDST, patch-pump delivery systems (“patch pumps”) are discussed. Patch pumps are novel insulin delivery systems that have emerged on the market; offering flexible insulin delivery options. These systems offer several advantages over conventional insulin pump delivery systems and are gaining popularity. Patch pumps are free of tubing, small, and lightweight. In this special section, the authors discuss both the simple and complex patch pumps currently available on the US market as well as those that are currently under development. Current technologies used to operate these pumps are discussed in detail, and potential promising technologies are presented. Available data on patient preferences, clinical trial data, and the future of patch pumps are discussed.

Approximately 30 million people in the U.S. have diabetes mellitus (DM), and nearly 9 million of these would be estimated to be on insulin therapy.^1,2 Employment of continuous subcutaneous insulin infusion (CSII, or “insulin pump”) therapy for insulin delivery has increased over the years, the vast majority occurring in the type 1 DM population. Despite the fact that patients with type 1 DM who use CSII have better clinical outcomes, only about 30% of these patients have adopted this technology. ³ Insulin “patch pumps” are an emerging technology and represent an exciting addition to the insulin delivery options currently available to patients. In this special section of JDST, six articles describe current and future patch pump technologies. Highlights of these articles are summarized in this commentary.

Ginsberg et al provide an overview of the patch pumps currently available. ⁴ They vary in complexity, and may offer appropriate functionality in both type 1 and type 2 DM. The article by Ginsberg classifies patch pumps into simplified (mechanical only) or full-featured (mechanical pump with electronic controller) devices. All are disposable or semidisposable, and do not require use of a catheter. Of the simplified devices, the only one available in the U.S. is the V-Go, which must be replaced daily. It provides a fixed basal rate and a fixed bolus dose as prompted by the user. The PAQ by Cequr (discussed below) is available in Europe. It is a 3-day device with a small reusable electronic portion. The Finesse patch pump is FDA approved but not yet available in the U.S. This device provides bolus dosing only with a patient prompt. These simplified devices are generally geared toward type 2 DM. There are 8 full-featured devices described by Ginsberg. The only one available in the U.S. is the Omnipod by Insulet. Full-featured devices such as the Omnipod offer a range of functionalities (eg, variable basal rates, controlled bolus amounts, advanced bolus options).

In the article by Heinemann et al, a general overview of current and potential patch pump technologies is also presented. ⁵ The potential advantages and disadvantages of patch pumps and the costs of these devices are summarized. The article argues that conventional CSII therapy pumps tend to be bulky, expensive, and tether the patient by tubing. Insulin infusion sets (IIS) can be prone to clogging, kinking of the tubing, or obstruction of insulin delivery with air bubbles. In contrast, patch pumps are generally smaller and attach directly to the skin without tubing. Surveys indicate that most patients with type 1 diabetes (T1D) prefer insulin pumps without visible IIS; making patch pumps an attractive insulin delivery option.^6,7 In addition, the article underscores the paucity of randomized clinical control data and emphasizes the need for more robust clinical evidence to support use of this technology.

The third article, by Lilly et al, describes the PAQ by Cequr: a small, simplified patch pump that delivers insulin for up to 3 days. ⁸ It uses rapid acting insulin to deliver a preset basal (7 basal options offered) as well as patient prompted boluses in 2 unit increments. The PAQ is currently available only in Europe. This device is targeted to patients with type 2 DM as an incentive to overcome known barriers to insulin delivery in this population. Focus groups were conducted to identify the needs of this patient population, and the consensus was that “users want a way to administer insulin that is simple, discreet, safe, and effective.” Human factors testing of the PAQ concluded it was easy to learn with 100% of participants successfully completing the tested performance measures. A small study demonstrated minimal skin irritation with good patch adherence. Additional studies indicated high patient satisfaction and improved glycemic control compared to injection therapy. ⁸ While the available studies indicated high patient satisfaction and better glycemic control in type 2 DM, there are no head to head trials comparing the PAQ to other patch pumps or conventional CSII therapy.

The Omnipod DASH by Insulet is also discussed in detail. ⁹ This is a full-featured device currently in use as the Omnipod Insulin Management System in Europe, Canada, and the U.S., and the Omnipod DASH system, was recently FDA approved for use in the U.S.. This device consists of an insulin containing “pod,” which is worn on the body and delivers insulin, plus a wireless Personal Diabetes Manager (PDM) connected to the pod that controls insulin delivery. The Omnipod has several differentiating features from conventional CSII therapy including a tubeless waterproof pod and automated priming and cannula insertion. The Omnipod DASH system has a touchscreen PDM interface, Bluetooth wireless technology, and wireless internet connectivity. Efficacy data in youth and adults with type 1 DM transitioned from both insulin injection therapy and conventional CSII to the Omnipod system demonstrated improvement in glycemic control. ¹⁰ In addition to improved glycemic control, patients reported improved quality of life (QOL) with use of the Omnipod system compared to their previous treatment modality. ¹¹

Novel future technologies aimed at improving the functionality and accuracy of current patch pumps are included in this series. In the article by Payne et al, the ePump microfluidic technology is discussed. ¹² This method utilizes electro-chemiosmotic rather than mechanical pumping, allowing for accurate delivery of very small amounts of insulin including concentrated insulins. In addition, the liquid working material eliminates size and shape constraints of the pump, allowing for the development of smaller insulin pumps. The authors propose that this technology can be built quickly and at low cost. An additional feature of this technology is a built in instantaneous occlusion sensor, which would allow detection in a timely manner. Moreover, the authors indicate there is potential for dual hormone delivery through separate fluidic pathways using the same pump engine. This makes dual hormone delivery (insulin and glucagon) a future possibility for a potential artificial pancreas system.

The last article in this symposium by Chen et. al. discusses the promising novel technology of microneedle (MN)-array patches for transdermal delivery of insulin. ¹³ MN-array patches use micron-sized needles, would cause minimal pain, and can be placed easily. Several prototypes of glucose-responsive MN-array patches have been developed with the capability to sense the current blood glucose value and secrete the appropriate amount of insulin to keep blood glucose in range. Chen et al discuss the concept of the “smart insulin patch” and the prototypes currently available and under development. This technology is exciting in that a transdermal closed-loop drug delivery system would represent a desirable form of insulin delivery. Studies thus far have been in rodent models only.

As outlined in these series of articles, patch pump therapy represents an exciting advancement of current CSII therapy, potentially allowing for more increased patient satisfaction. Given the range of functionalities offered with this technology, it may be appropriate for both type 1 and type 2 DM. However, adoption of these technologies by patients, clinicians, and insurers requires more randomized controlled data. Adequately designed and powered clinical studies are needed comparing patch pumps to conventional CSII and insulin injections across a spectrum of patients with DM, including children, adolescents, adults, and the elderly. In addition to glycemic control, these studies should assess safety, patient satisfaction, and QOL before they can be widely advocated for use.