The usual insulin regimen enables to secure sufficiently good treatment as much as adequate life comfort for most Type 1 diabetics. There are, however, some patients who do not respond well to this course of treatment and their diabetes is not under control in a sufficient way. There may occur cases of frequent hypoglycemia or high morning hyperglycemia (the dawn phenomenon) which the change in dosage or the employment of a different insulin (insulin analog) cannot solve.
An insulin pump is a box containing a processing module managing its functioning and an insulin reservoir. Insulin is introduced into the body in the abdomen by a cannula which is inserted subcutaneously.
The principles of the pump treatment
The principle of the treatment by an insulin pump and its main advantage is the possibility of programming the insulin doses for a particular day as well as during the night hour (a basal dose). A certain amount of the administered insulin (approximately a half) is then delivered following this scheme automatically and the rest then in bolus doses before main meals following the patient’s instructions just as has been done so far in the usual insulin regimen.
In this regimen, the basic need for insulin is secured with the help of long-acting insulin. If we want to increase the basal amount of insulin in a specific time of a day (by increasing the dose of this insulin), then it is automatically increased in all other periods of a day which may cause hypoglycemia.
These reasons make it very difficult to set an optimum dose scheme in a number of patients. An insulin pump eliminates this disadvantage as we may simply change the program to increase or decrease the basal dose for a specific day period. An insulin pump thus enables us to optimalize the basal insulin dose following the needs of each individual patient. The total amount of insulin needed for the treatment is then normaly lower by 10-30%, this being its further advantage.
The most frequent reasons for using an insulin pump:
- unstable diabetes with frequently reccuring hypoglycemic episodes, the number of which cannot be influenced by any insulin regimen.
- hypoglycemia events which may not be easily identified by a patient, potentially dangerous and may lead to a hypoglycemic comma.
- hyperglycemia experienced in the morning (the dawn phenomenon) which is necessary to be dealt with by another insulin dose in the early morning hours.
- to manage diabetes well in patients with badly compensated diabetes during the period before an intended pregnancy.
- in badly compensated but cooperating diabetics especially with a rapid development of specific complications of diabetes.
- in patients before and after planned organ transplantations.
How to determine the dose of insulin
When estimating the dose, we begin with the total daily insulin amount which the patient has been treated with recently. We take into account that when treated by the pump, it may mostly be decreased by 10 - 30% at most. We then distribute 40 – 60 % of the new total dose amount among the basal doses depending on the individual characteristics of each patient. When determining the dose, we take into account physiological laws which state that glycemia tends to be lowest in the early morning hours between 4 a.m. and 7 a.m.
We are also interested in the life patterns of a patient, i.e. working hours, the distribution of meals, sportive activities, the most frequent time of hypoglycemia, etc. It is evident that each patient is an individuality in his/her own and must be approached as such– still, it is possible to find certain similarities between the treatment patterns.The resulting example of a basal set up, as shown in the picture, may (with certain changes applied to it sometimes) be used in the majority of „standard patients“. Determining the bolus doses is based on the quantity of food included in each of the meals and the present situation just as in a common insulin regimen.
How does an insulin pump work?
Using an insulin pump requires a regular change of insulin reservoirs (in some of the pumps, a prefilled insulin cartridge similar to the one used in pens is inserted, in most cases the patient has to fill the reservoir with insulin himself). The reservoir will last depending on the daily provided amount of insulin. In individual patients it ranges between 2 and 5 days. The sets conducting insulin into the subcutaneous parts are changed once in 3 days. The most frequent place where the set is introduced is the abdomen, mostly in the vicinity of the navel, where there is a sufficient layer of fat.
Buttocks, the front part of the thighs and arms rank among the other recommended but, for obvious reasons, less employed places. The choice of an optimal place depends on the experience of a patient and is completely up to them. The parts introduced in the subcutaneous areas of the body are made of teflone produce a minimum irritation effect.
Pump types
There are 4 different marks of insulin pumps registered in the Czech Republic at present, with a quality background and services provided to the patients by the manufacturers and importers. There are no substantial differences in the functioning between the pumps, perhaps except for the latest version of the pump manufactured by Medtronic, which combines an insulin pump with the possibility of a continuous glycemia monitoring system. The choice always depends on the agreement between the patient and the prescribing physician.
Current functioning of the pump
According to our experince, the first uncertainty of a patient deriving from the necessity of carrying the pump on him/her at all times very soon disappears and there does not occur any further anxiety concerning the treatment. There is, however, fear connected with the daily routine tasks, such as taking a shower, a bath, swimming in the pool. The present day cannulas may be put apart easily and the pump may be disconnected (this periods should not exceed 120 minutes) so there are not any substantial limitations of the patients in this respect.
Possible drawbacks of insulin pump treatment
When starting the pump treatment therapy we always always bring forth the two greatest dangers of its use. The first one is a possible interruption in the release of insulin caused mostly by a blocked cannula which can also be torn out of the body. This may then result in a state when there is not any reserve supply of insulin in the body which may very quickly lead to the development of ketoacidosis which, moreover, need not be accompanied by a more pronounced hyperglycemia as is usual in normal insulin regimen. When treating the patients, we always warn them about this possibility, which is not frequent and many patients have never really come across it.
There may occur a situation when glycemia rises above 15 mml/l especially when accompanied by gastrointestinal symptoms, it is necessary to inspect carefully the system of the pump and verify that insulin is really directed into the body. And then, of course, to deal with hyperglycemia by a small bolus dose of insulin.
The second weak point of this therapy is the place where the cannula is introduced, here infection or inflammation may occur. These complications are rare today with the materials which are employed. It is, however, necessary to keep the common hygiene and antiseptic rules. So the place where the set is going to be introduced should be washed with desinfectants, the same after its removal. The set should not be used for more than three days.