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[IPk] Diabetes Update pump article - full text

Reproduced with permission from Diabetes Update pp18-20, Winter 1999

Insulin pumps

Although large numbers of Type 1 patients around the world currently use
insulin pumps to manage their diabetes, in the UK their use is limited and
has raised a number of concerns among diabetes care teams. Dr John Pickup
examines the whys and wherefores of this controversial treatment option.

Insulin pump therapy is the common name for the technique of continuous
subcutaneous insulin infusion (CSII). This form of intensive insulin
treatment uses a portable, battery-driven pump to infuse short-acting
insulin subcutaneously via a fine cannula, which terminates in a needle.
The infusion rates are accurately controlled by the pump essentially, a
slow basal rate throughout the entire 24 hours, supplemented by boosts at
or shortly before meal times. This is a way of mimicking the multi-rate
insulin delivery from the pancreas in people without diabetes and thus
obtaining very good metabolic control. It has the particular advantage over
conventional injection regimens, which use long-acting insulin like
isophane or Lente, of producing a completely constant basal insulin
delivery. CSII pumps am worn on the outside of the body; insulin pumps that
am implanted within the body am also undergoing evaluation, but in no
country am they yet considered a routine treatment option.

CSII was developed in the UK (at Guy's Hospital, London) in the late 1970s,
specifically for use in research studies trying to show the effect of very
good blood glucose control on diabetic complications. Over the years,
insulin pumps have been used for obtaining strict diabetic control in
several major trials of control and complications, including (along with
multiple insulin injections) the famous Diabetes Control and Complications
Trial (DCCT) in North America. However almost from the start of
experimental CSII testing, pumps were being considered by some doctors for
routine use in patients with Type I diabetes.

The early pumps were rather bulky and uncomfortable to wear and were
technically unsophisticated with limited choice of infusion rates and
safety features. But today's pumps am much smaller about the size of a
pager and microprocessor-based button control allows a wide range of rate
settings. This improvement has encouraged non- research pump therapy and in
some countries insulin pumps have become an established treatment for
selected patients with diabetes. According to figures for pump
manufacturers, in the USA mom than 50, 000 people with diabetes and in
Germany about 20, 000 people am using a pump. lnterestingly, the home base
of CSII, the UK has embraced this technology with much less enthusiasm, and
only about 300 pumps are currently in use here; about 10, 000 would be
needed to match the same percentage of patients with Type I diabetes as use
CSII in the USA.

Who is a suitable candidate for an insulin pump?

For most people with Type I diabetes, the quality of blood glucose control
achievable with CSII is very good but broadly similar to the best modern
injection regimens, so there is no particular advantage to using a pump. In
a comparatively small number of people, all attempts to maintain strict
control with injections have failed and in some of these, CSII may be
helpful and should be considered.

The best established clinical indication is frequent and?or unpredictable
hypoglycaemia, where several clinical trials have shown clear improvement
in control (ie reduced hypoglycaemia) and consequently lifestyle with pump
therapy. Another indication is a marked rise in blood glucose in the few
hours before breakfast (the so-called 'dawn phenomenon'); this is thought
to be due to excessive hormone secretion after the start of sleep and its
timing at the point when evening long-acting insulin is running out can
lead to difficult control in a few patients. The ability to pre-set insulin
infusion rate changes during the night with the pump, such as an automatic
increase from 3.00am to 9.00am helps to counteract the pre-breakfast
glucose increase.

The type of patient with extremely 'brittle' diabetes, usually insulin
resistant and adolescent, who suffers from frequent episodes of
ketoacidosis is, unfortunately, not generally helped by CSII. Psychological
problems and deliberate interference with treatment are suspected in some,
often many, of these cases, which might explain the poor success of pumps
in this worrying condition. As always, -there are exceptions, and a few
patients with frequent ketoacidosis are described who have been improved by
CSII. li, is worth noting that the failure/success of CSII can be used as
an investigative tool to exclude errors of insulin injection timing and
dosage as a cause of brittle diabetes.

Some busy or much-travelled people with an erratic lifestyle who often
delay or omit meals may find stable control easier to achieve with a pump
than injection therapy, because of the constant basal insulin delivery arid
the ease of meal-time boosts. Finally, there are those in whom pump therapy
is less of an absolute clinical requirement than a personal choice: they
may simply prefer to get the best control with CSII rather than giving
multiple injections and may be willing to pay for pump arid supplies. When
the cost is borne by health insurance, as it is in the USA and some
European countries, simple patient preference is easier to justify,
especially if it is an accepted indication. Perhaps the alternative of
strenuous and prolonged attempts to achieve good control with optimise
injections is given less of a priority. This might be no bad thing.

There have been few studies of CSII in people with Type 2 diabetes, and it
is not generally considered an appropriate management option.
Interestingly, when it has been tried in Type 2 diabetes poorly controlled
on insulin injections or combinations of oral agents, significantly
improved control has been achieved.

I will choose 5 per cent as a working figure for the proportion of people
with Type 1 diabetes who might be candidates for CSII. This figure is based
on personal experience of successes and failures, pump use in other
countries and published information, but there is no real scientific
credence to this estimate. Of this 5 per cent, many patients will be
unsuitable for the reasons given below, and given - the competing demands
for resources in the UK, putting 1-2 per cent of people with Type 1
diabetes on CSII might be a realistic target figure to aim for in the next
few years.

The prerequisites of pump treatment

Patient selection is very important. In addition to a clinical indication,
patients must be willing, motivated and capable of undertaking CSII and its
monitoring procedures, particularly frequent home blood glucose testing.
Significant psychological problems are also thought to be a
contraindication to starting CSII. Some will find pump treatment demanding,
intrusive and perhaps uncomfortable, and the possible disadvantages must be
presented and balanced against the probable benefits. On the medical side,
a skilled team must be in place to teach and monitor pump therapy, and this
can and does now include educators and instructors from the pump

Pumps and their costs

There are two manufacturers supplying pumps in the UK. The Minimed model
507 has fully adjustable multiple basal rates and costs 1,950; a single
basal rate version (model 505) costs 1,150. Minimed pumps and supplies can
be obtained in the UK from its distributor, Applied Medical Technology. The
company's estimated lifetime for the Minimed pump is seven years.

The Disetronic H-Tron Plus V100 pump costs 2,000 for a two-pump set, each
of these Disetronic pumps having a programmed two-year lifetime. Supplies
include delivery cannulae, pump syringes or cartridges (the insulin
reservoir in the pump) and pump batteries, and cost about 15 per week.
Other manufacturers are set to enter the market, such as the Korean company
Sooil, with the DANA Diabecare pump, which is claimed to be the smallest in
the world.

Whereas in the US and Germany, pump costs are met by the patient's health
insurance, in the UK most health authorities do not pay for either the pump
or the disposable supplies. At the moment, UK funding for CSII is met by a
mixture of private donations to hospitals, local charities, research trials
(patients are often allowed to keep the pump on completion of a study),
Patient purchase and the persistent arguing of the case to local health
authorities, which may produce funds for either pump or supplies for a few
named individuals.

How to put patients on the pump

Both Applied Medical Technology (for Minimed) and Disetronic have nurse
educator/instructors who will initiate pump therapy either at the patient's
local diabetes centre or at home, according to physician's instructions.
Experienced centres where many patients are put on CSII may have their own
medical and nursing team who undertake this task. Though there were
concerns a few years ago that it would be possible for patients to acquire
(and a manufacturer to supply) pumps without the knowledge, approval and
subsequent supervision of their diabetes doctor, both AMT and Disetronic
state that they will only supply and instruct patients with the approval of
and in close co-operation with the doctor managing the diabetes.

Until recently, buffered shod-acting insulin (Velosulin, Actrapid, Humulin
s) has been used for CSII, but it is now well established that the
monomeric insulin analogue, lispro (Humalog, Eli Lilly) produces improved
control on CSII without increasing hypoglycaemia. In most cases, lispro is
now the pump insulin of choice, though the occasional patient may still do
better on conventional shortacting human insulin.

A typical infusion strategy is to reduce the usual total daily insulin dose
on injections by 10 per cent, and to give half as the basal pump rate
(about 0.9-1.0 U/h) and half divided amongst the three main meals. As with
insulin injections, the meal-time boosts are given about 30 minutes before
the meal when ordinary short-acting insulin is in the pump reservoir, and
with the meal when lispro is used. over the first few days, the fasting
and, if possible, the 3.roam blood glucose concentration are used to adjust
the basal rate, and the post-prandial glucose value used to adjust the
mealtime insulin boost. Most patients can be managed by between one and
three basal rates over 24 hours. The abdomen is the preferred site of
infusion, with the pump usually worn around the waist. The delivery cannula
should be changed and re-sited every 48 hours.

A comprehensive education programme includes home blood glucose monitoring,
insulin dosage adjustments, what to do in the case of illness, exercise,
hypoglycaemia or pump breakdown. In the event of pump malfunction, AMT will
supply a replacement Minimed pump within 24 hours, and for the Disetronic
device, replacement is with the alternative pump in the set, a new second
pump being loaded until the faulty device is repaired. The patient must, of
course, have syringes, insulin or 'insulin pens'for emergency reversion to

Life on the pump

Moderate exercise without hypoglycaemia is easily managed on the pump by
reducing the basal rate infusion - one half (some pumps have a built-in
'temporary basal rate' command) for the duration of the exercise.

The usual routine follow up is by clinic reviews every three months, and
between hospital visits continuous contact with the diabetic team should be
available by telephone for advice on problems and emergencies. Pump therapy
has been associated with increased risk of diabetic ketoacidosis (DKA) in
the past but most of the relevant literature is over 10 years old. It is
very possible that these original data result from less sophisticated
devices and management algorithms. Good patient (and professional)
motivation and understanding, with careful patient self-monitoring, are
essential and the current clinical experience in the Us and several
European countries suggest the risk can be kept low.

The latest ADA position statement on CSII states: "Pump therapy is as safe
as multiple-injection therapy when recommended procedures are followed"
(Diabetes 1999; 22 (suppl 1): 87). At least two studies show that the rate
of ketoacidosis (and severe hypoglycaemia) are actually less on CSII than
in comparable injection-treated people with diabetes (Chantelau E et al.
Long term safety, efficacy and side effects of continuous subcutaneous
insulin infusion. Diabetologia 1989; 32: 421-426; Bode B et al. Long-term
pump use and SMBG in 205 patients. Diabetes 1994; 43 (suppl 1): 220).

There is a potential risk of ketoacidosis on CSII, of course, because of
the small depot of insulin under the skin at any one time, and interruption
of pump insulin will cause a fast metabolic deterioration. Hence the need
for careful monitoring, and chantelau et al. emphasise the importance of
patient education to minimise the risk. on the basis of these and other
studies, however, it is this author's belief that where proper procedures
are followed ketoacidosis is no more common on CSII than on injection
treatment, and that pumps are at least as safe a diabetes therapy as
insulin injections.


In some countries, such as the USA, it has been agreed that when insulin
pump therapy is prescribed by a physician in accordance with recommended
guidelines, it should be covered by 'usual funding mechanisms'. The
requirements in the guidelines are for careful selection of patients, a
skilled team, rigorous patient education and thorough monitoring. The very
large numbers of people with diabetes who are being treated by CSII and who
chose to continue with this treatment, is evidence that it is an
appropriate mode of therapy for at least some patients.

We have probably not yet reached a consensus in the UK that CSII is of
definite value for some specific management problems in diabetes, nor that
it is allowable for patients to choose CSII as their preferred treatment,
indecision which is inevitably influenced by the funding difficulties. A
submission concerning CSII has recently been made to the National Institute
for clinical Excellence (NICE), which may help to clarify its place in
diabetes management.

The BDA will be publishing a position statement on insulin pumps in the new

Diabetes Update Winter 1999

copyright 1999, British Diabetic Association

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