Insulin pump therapy started in UK in 1976. Insulin pumps deliver a continuous basal insulin infusion (CSII) and patient-activated bolus doses at meal times. The pump is attached to the patients by an infusion set consisting of long flexible tubing with a needle or catheter on the end and is inserted subcuta-neously in the patient. In two meta-analysis CSII was compared with conventional insulin treatment [29,30], which is not the actually used MDI. CSII caused a significant reduction in HbAlC of the size of 0.4-0.8% [29,30]. This degree of improvement in glycaemic control for 10 years would reduce the number of patients developing retinopathy by about 5% . Using SIA for CSII provides a further small, but statistically significant improvement in glycaemic control (- 0.19% in HbAlC) as compared with regular insulin . Therefore, the insulin of choice for CSII is now SIA. The frequency of hypo-glycaemia is less after CSII treatment rather than after MDI treatment in more recent studies but is not affected if SIA is used instead of regular insulin . With proper education and pump practice, the frequency of ketoacidosis is the same on CSII and MDI. A marked rise in blood glucose before breakfast, the so-called 'dawn phenomenon', occurs quite often in T1DM. It is due to a combination of waning of the circulating insulin concentration from the previous basal insulin injection and an increase in insulin resistance caused by nocturnal rise in growth hormone. If moving of the injection time of the previous basal insulin or a dose increase does not solve this problem, the modern CSII treatment with pre-programmed increase in the late night/early morning can minimize the dawn blood glucose increase. Clinical guidelines are the first step in making standards of care explicit. Table 3 gives the indications for CSII in T1DM suggested by a Danish expert committee . CSII should be cancelled in case of recurrent ketoacidosis, if HbAlC increases, recurrent local infections/reactions, and when lacking compliance [32,33]. There ought to be demands on the CSII treatment teams about knowledge and education, experience and organization and monitoring [32,33]. The total insulin requirement per 24 h usually decreases 15-20% after starting with CSII. Approximately 40-50% of the daily insulin doses are given as the basal rate, but some patients require up to 60%. The remainder is given as premeal bolus doses. The insulin requirement in adults is about 20% lower between 01 and 03 A.M. compared with that between 05 and 07 a.m.. Standard advice is to decrease the basal rate during the night and after physical exercise and to increase in case of intercurrent illness with a rise in plasma glucose levels. Approaches with carbohydrate counting to the nutritional management of T1DM allow adjustment of premeal insulin boluses to both the premeal glucose levels as well as the carbohydrate content of the meal. Calculation of insulin to carbohydrate ratios allows increased flexibility in meal planning. Testing for ketones is mandatory if plasma glucose is >15 mM for more than a couple of hours or if the patient is ill or is nauseous/vomiting. The evidence suggests that the expanding use of CSII is justified. Despite the fact that a number of patients could greatly benefit
Table 3. Indications for insulin pump treatment (CSII) in T1DM.
CSII should be offered to subjects with T1DM who are not satisfactorily controlled on MDI, that is having HbA1C >7.5% (>7.0% for women who want to become pregnant) in case this is due to one or more of the following reasons:
If the patient despite optimized treatment inclusive of a dose increase of insulin experiences recurrent and/or unpredictable hypoglycaemic events If the patient has hypoglycaemic unawareness
If the patient has erratic swings of blood glucose concentrations or an erratic lifestyle with delayed or missed meals and/or unpredictable activity If the patient cannot control night time blood glucose levels on MDI even after having tried a long-acting insulin analogue, for example, patients with dawn phenomenon where the dose of basal insulin cannot be increased due to nocturnal hypoglycaemia And under the prerequisite that the unacceptable treatment with MDI is not due to: Not wanting to measure HBGM to a sufficient degree (>4 times daily)
Insufficient compliance and/or understanding of the interplay between insulin, diet and exercise for an affordable cost, there is still unwillingness in some countries to fund and reimburse insulin pump therapy . CSII in T1DM is therefore very unevenly used and available in Western countries where, for example, only a few percent of T1DM in Denmark, around 10% of T1DM in Norway and Sweden and maybe up to 20-25% of T1DM in USA, are on this treatment .
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