Optimised diabetes therapy with insulin patch pumps

Switzerland

Insulin therapy for type 1 diabetics was revolutionised in the early 1990s by the Diabetes Control and Complications Trials (DCCT).(1) The results showed that optimal blood glucose levels are achieved and complications are prevented only by insulin therapy adjusted to individual requirements. Since then, intensive conventional insulin therapy (ICT) with separation of basal insulin and bolus insulin has been regarded as standard therapy for patients with type 1 diabetes. Patients check their blood glucose level regularly and adjust their insulin delivery accordingly.

However, ICT has its limits: slowly acting basal insulin makes flexible adjustment to actual need difficult, for example, during sports or illness, and problems such as high blood glucose levels in the early morning (dawn phenomenon) with a simultaneous risk of nocturnal hypoglycaemia have not been solved. By contrast, insulin pump therapy represents insulin delivery adjusted to physiological needs. It allows continuous delivery of short-acting insulin that meets the patient’s requirements.

The development of insulin pump therapy began in the early 1960s. A prototype was developed that administered insulin and its counterpart, the hormone, glucagon. The pump functioned well but had disadvantages: it was as bulky as a large rucksack, the hormones were administered intravenously and an extension lead was required. The next generation of insulin pumps arrived on the scene only in the late 1970s, when Dean Kamen in the US introduced a portable insulin pump with integral syringe – the Autosyringe, which was nicknamed the ‘blue brick’ because of its appearance. In Europe, the first pumps were developed by John Pickup, who is now Professor of Diabetes and Metabolism at Guy’s Hospital in the UK. The breakthrough for the development of modern insulin pumps came in 1985 when the Swiss manufacturer, Disetronic, marketed the MRS1-Infusor. This pump was the size of a cigarette pack, had an hourly variable basal rate, was worn on the body and delivered the insulin into adipose tissue through a catheter and a cannula. Pump therapy had thereby moved from the experimental stage to a recognised treatment option.

Over the next two decades, pumps became even smaller and more intelligent. Insulin delivery was improved and it became possible to calculate and record the administered doses.

Two categories of insulin pumps are currently available: conventional insulin pumps and insulin patch pumps.

Conventional pumps are roughly the size of a pack of cards and are connected to the subcutaneous fat via a catheter 30–110cm long with a cannula. A patch pump is smaller and does not use a catheter as it adheres directly to the skin. 

The first available patch pump, mylife™ OmniPod® (Insulet Corporation/Ypsomed AG), has been available since 2005; the pump (pod) comprises the insulin reservoir, soft cannula, inserter, batteries and pump mechanism.

The pod is controlled by wireless communication via the Personal Diabetes Manager (PDM). After filling with insulin, the pod is stuck to the skin for three days and can remain fixed there even when showering, swimming or taking part in sports because it is waterproof. The soft cannula integrated in the pod is introduced almost painlessly into the subcutaneous fat automatically within 0.005 seconds. The automatic insertion means that the pod can be positioned on the abdomen, buttocks, thigh and upper arm. The additional sites help to reduce the incidence of lipohypertrophy and thereby guarantee an adequate supply of insulin. The problems that arise with conventional pump therapy such as kinked or detached catheters can be avoided with the tubeless patch pumps. Treatment compliance of patients is very high with the patch pump, as the restrictions on movement during occupational or sporting activities are markedly improved by the catheter-free insulin infusion.

The mylife™ OmniPod® patch pump is currently the only available patch pump that guarantees real continuous insulin delivery. Because the pod is waterproof and does not have to be removed for showering or swimming, the question arises of what positive influence this has on blood glucose control. In a prospective unblinded study,(2) the influence of short-term disconnection of the infusion set of conventional insulin pumps on the blood glucose levels of 19 type 1 diabetics was investigated. It was shown that a 30-minute interruption of the basal insulin delivery leads to a significant elevation of the blood glucose profile. The glucose concentration rose by 1mg/dl for each minute in which the insulin infusion was interrupted in a period of three hours.

Apart from the possibility of achieving better metabolic values due to continuous insulin delivery, the question arises of how type 1 diabetics who have already had intensive experience with a conventional pump assess the mylife™ OmniPod®patch pump. A randomised two-arm crossover study published in 2012(3) showed that the mylife™ OmniPod® patch pump is also well accepted by experienced insulin pump users. All 29 study participants were type 1 diabetics with at least one year’s experience of treatment with conventional insulin pumps. In the two consecutive twelve-week study phases, the mylife™ OmniPod® patch pump was compared with conventional insulin pump therapy. The main target criteria were satisfaction with treatment, assessment of user friendliness and the HbA1c level.

Despite high treatment satisfaction before the start of the study, at the end of the study 43% of participants stated that they would change to an mylife™ OmniPod®, 36% were undecided and 21% would not change their insulin pump. The relatively high percentage of study participants who wanted to continue treatment with the mylife™ OmniPod® patch pump shows how well the patch pump was accepted. The system characteristics that received the highest average assessments for user satisfaction with the mylife™ OmniPod® system were the integrated automatic insertion of the soft cannula and the pod’s watertightness. A total of 76% of study participants preferred the automatic system for inserting the cannula in the mylife™ OmniPod® system. With the PDM, the tubeless connection, the integrated blood glucose measurement system and the bolus calculator received particular emphasis. The mylife™ OmniPod® system received the lowest scores for the wearing time of three days, for the size of the PDM and for the transmission distance between pod and PDM.

Overall, 55% of the patients stated that the mylife™ OmniPod® would suit their lifestyle better than the conventional pump. Examples of this, in particular, were the ability to wear the pod while showering, and wearing it during sleep and physical activity.

After the conclusion of the first phase of the study, the HbA1c levels had reduced significantly in both treatment groups (7.9±0.9% versus 8.8±0.7% and 8.2±0.9% versus 8.5±0.5% for both groups). In the mylife™ OmniPod®group, the reduction in HbA1c was more marked (p=0.044). At the end of the study, a further improvement was not seen in either group.

Finally, the study established that the mylife™ OmniPod® patch pump was very well accepted and the marked improvement in the HbA1c level demonstrates that it possibly confers further advantages.

The second generation of the mylife™ OmniPod® patch pump has now been available since October 2012. The most important improvement in the pod for patients comprises the reduction in weight and size. The pod weighs only 34g when filled with 200U insulin and thus promises to increase patient satisfaction further. Moreover, improvements were made with the PDM with regard to the communication distance and system functions.

In a study recently conducted in Germany, the user preference of 50 diabetic patients experienced in pump therapy was investigated with regard to the second generation of the mylife™ OmniPod® patch pump. Initial results(4) show that many experienced pump users prefer the tube-free pump because of the increased flexibility compared with a conventional insulin pump.(4)

The fact that patch pumps will play an important role in insulin pump therapy in future becomes obvious when the efforts of other leading companies to bring a patch pump to the market are considered. For example, Roche Diabetes Care is developing the Solo MicroPump, a patch pump with a modular construction. The pump consists of the pump base with a motor and insulin reservoir along with a base plate. It is operated using remote control. 

Cellnovo is currently developing a pseudo patch pump consisting of a pump with a nearby infusion site and remote control in Smartphone format. With the Cellnovo product, the possibility of monitoring activity should be emphasised, which can influence the calculation of the required insulin dose. There are other patch pump developments apart from the products above, but the mylife™ OmniPod® patch pump is currently the only patch pump available for patients.

1. Diabetes Control and Complications Trials. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;329(14):977–86.
2. Zisser H. Quantifying the impact of a short-interval interruption of insulin-pump infusion sets on glycemic excursions. Diabetes Care 2008;31:238–9.
3. Lebenthal Y et al. Patient perceptions of using the mylifeTM OmniPod® system compared with conventional insulin pumps in young adults with type 1 diabetes, Diab Tech Ther 2012;14(5):411–17.
4. Insulet Corporation. Data on file.