Insulin Infusion Pumps (CSCII)

Do you think a pump is for you? Insulin infusion pumps are modern, computerised devices which infuse insulin at a low dose continuously under the skin via a catheter. They are small, and carried round on a belt like a walkman! For some people, they can improve control, with fewer episodes of hypos. NICE guidance tells us who might benefit and who will be funded by the NHS. However, the quest for a pump can be as difficult as the journey to Mount Doom in Lord of the Rings! There is enormous variation in the willingness of the local providers (PCTs) to fund them. But help is at hand, we have some tactics for you to beat the system! Read about the pump, and decide for yourself! Our specilist pump nurse will be adding some content this week, so remember to look back.

You should consider a pump if you are-

• having hypos at night, and adjusating your basal insulin isn't helping.
• You are not getting your HbA1c down, even though you are doing lots of tests and making lots of changes to you doses.
• doing lots of different activities or sport which are difficult to predict.
• you are having to take a lot of extra glucose or food to stop you going low during or after sport.
• you are fed up of doing 4+ doses per day!

The role of CSII and exercise

Insulin pump therapy gives a level of flexibility of insulin delivery not available to those on multiple daily insulin injections. Particular benefits are the ability to change the basal infusion rate in small increments and with relatively rapid effect, the fact that there is only a small subcutaneous reservoir of insulin, and the ability to make multiple additional boluses does of insulin without additional injection. These seem to offer a near ideal solution to the some of the problems of insulin therapy and sports.

Although ideally dose adjustments should be made at least 30 minutes before starting exercise, pump therapy does allow for impromptu activity, which can be beneficial especially in younger people. Young people with diabetes who suspend basal insulin during exercise suffer significantly less hypoglycaemia when compared with those who continue their usual basal rate during exercise , but it should be noted that this results in a significant increase in post-exercise hyperglycaemia. This is important, as it increases the risk of deterioration in overall glycaemic control, and more importantly the risk of ketosis. An alternative strategy is to continue basal insulin during exercise , with the rate reduced depending on the intensity and duration of the exercise, and this seems now to be the preferred option. However there are as yet no studies to advise what would be an appropriate basal dose reduction (or even increase) for various type and duration of exercise, and how long before and after exercise that these changes should best be made.
Following intense exercise, hyperglycaemia may be problematic. This can be managed with a corrective bolus dose of insulin, and may be anticipated with experience.

The tendency to post exercise nocturnal hypoglycaemia can also be more effectively managed with CSII. Our clinical experience demonstrates that in people who are performing exercise less frequently than alternate daily, nocturnal hypoglycaemia can be reduced without compromising overall glycaemic control (including morning fasting glucose readings) by reducing the basal CSII rate by 20% on the night following exercise. Again this clinical observation needs to be confirmed by clinical studies.

Lastly we need to address the issue of performance. Perhaps the most important issue is that by having ambient insulin levels closer to the physiological normal during exercise, insulin to glycogen ratio present to the liver, and ambient insulin levels during exercise are likely to be more normal. It would be reasonable to surmise that the need for carbohydrate ingestion will be reduced, and that the fuel use with exercise be more normal, with increased oxidation of other fuels than glucose, resulting in improved stamina and performance.