The limitations of insulin pump treatment

The pump brings many advantages, but it also has a few limitations that are worth knowing. It uses only one type of insulin, a rapid-acting one, and delivers your insulin through a thin cannula placed under the skin [1]. Being a device, it can develop technical problems at any time and it needs maintenance. In addition, the pump is worn almost all the time.

The second limitation lies with you, not with the device. The pump requires you to learn how it works and to react quickly when an alarm or a problem appears [2]. Costs can be higher, and some people do not feel comfortable wearing a device attached to their body. These limitations do not mean that the pump is a poor choice, but that it has to be used carefully and with good training, as the figure below shows.

A modern pump is built to warn you when something is not working properly. If a malfunction occurs, the device usually sounds an alarm or vibrates and displays a message, so that you know that insulin delivery has stopped [3]. In this way you have time to take action before blood glucose rises too much.

If the pump can no longer be used, the backup plan is to give yourself insulin with the insulin pen until you solve the problem. The syringe remains an option, although it is used less often nowadays. That is why you should always keep at hand a pen of rapid-acting insulin and a pen of long-acting insulin, checked to make sure they have not expired [4]. Your medical team will explain which doses to use in this situation.

Insulin delivery can stop for several practical reasons. Most often, the infusion set can become blocked or kinked, and the cannula can move out of place [5]. The reservoir can empty, the battery can run down, and sometimes the device itself develops a technical fault [6].

At other times the insulin is not absorbed properly, because the cannula was placed in an area with thickened subcutaneous tissue [7]. Any of these situations can stop insulin delivery, sometimes for hours on end and without you realizing it [8]. Pumps have an occlusion alarm, but it may come more than two hours late or not at all, so you usually notice the problem first through rising glucose [8].

Yes, ketone bodies, acidic substances produced when the body burns fat in the absence of insulin, can appear faster with pump treatment than with injections. The reason is that the pump uses only rapid-acting insulin and does not create a subcutaneous depot of long-acting insulin. If delivery stops, the body is left without insulin within a very short time [9].

Without insulin, at some point the body starts to produce ketone bodies, and these can build up in only a few hours [10]. When they accumulate in large amounts, diabetic ketoacidosis develops, a medical emergency that has to be treated in the hospital.

That is why, if your blood glucose is high and does not come down, check your infusion set. Also measure your ketones with urine ketone strips or with a blood ketone meter. Then give yourself insulin with the insulin pen. Taken in good time, these measures reduce the risk considerably, though they do not remove it completely. With ketones below 1.5 mmol/L, you hydrate, give your correction dose of insulin and recheck the ketones after two hours. If blood ketones are between 1.5 and 2.9 mmol/L, contact the medical team immediately. At 3.0 mmol/L or above, or if vomiting, difficulty breathing or drowsiness appear, go to the emergency room right away.

Most of the time, yes. The pump continuously delivers small amounts of basal insulin, which the body needs all the time, day and night. If you take it off for a long time, this delivery stops and blood glucose can rise [11].

You can disconnect it for short periods, for example in the shower, when swimming or during a contact sport [12]. What matters is that the pause does not exceed one hour. If it does run longer, give yourself the missing insulin according to the protocol agreed with your medical team. In this way you enjoy flexibility without your blood glucose rising too much.

The pump does not work entirely on its own. It needs your daily involvement. You have to count carbohydrates, give your meal boluses, monitor your blood glucose or sensor readings and respond to alarms [13].

Every few days you have to change the infusion set. In between, it is good to check the insulin level in the reservoir and the state of the battery [7]. This extra attention compared with injections may seem like too much at the beginning, but it becomes a simple routine once you get used to it. In exchange, you gain finer blood glucose control [14].

Yes, the skin in the area where you wear the cannula and the adhesive patch can sometimes become red, irritated or tender [15]. The adhesive, sweat and rubbing can cause itching or a small local reaction. In some people, repeated use of the same site leads to thickening of the subcutaneous tissue through local deposition of excess fat (lipohypertrophy) [7].

These problems can be reduced considerably if you regularly change the cannula site and clean the skin well before applying it. If you notice redness that does not go away, pain or signs of infection, tell your medical team [16]. Changing the cannula site in good time removes most irritations.

In general, yes. The pump is a more expensive device than insulin pens. Besides the device itself (the pump), you also need consumables, which are changed regularly, such as infusion sets and reservoirs. There may also be the cost of batteries and, if you use a pump integrated with a sensor, of the sensors [17].

The cost for you depends very much on how these devices are covered by health insurance (public or private) in the country where you live. It is worth discussing the expenses with the medical team early on, so that you know what to expect. The extra cost is justified mainly when, on injections, your glucose is hard to control or you have frequent hypoglycemia [17].

Yes. The pump is a very good device, but it is not the ideal choice for everyone. Some people do not feel comfortable wearing a device attached to their body. Others prefer the simplicity of injections or do not want to manage a fairly technical piece of equipment such as the pump every day [18].

Your own preference is, in itself, reason enough not to choose the pump. Perhaps you do not want to respond to alarms or to change the infusion set regularly. The choice of how your insulin is delivered is yours, made together with your medical team. If the pump does not suit you now, you can go back to injections at any time or you can try the pump later.

Yes, and this is one of the most important conditions for using the pump safely. The pump is a technical device. Before using it, you learn from the medical team how to program it, how to give boluses and how to change the infusion set [19].

The training you receive at the start of pump treatment also teaches you how to recognize a problem. You learn what to do when an alarm goes off or when blood glucose rises for no apparent reason. You will know when to switch to the insulin pen and how to avoid the build-up of ketone bodies [4]. With good training and the support of the medical team, using the pump becomes safer and easier.