Continuous subcutaneous insulin infusion as a treatment option: a perspective after seven years of research applications

Long-term safety, efficacy and side-effects of continuous subcutaneous insulin infusion treatment for type 1 (insulin-dependent) diabetes mellitus: a one centre experience

A follow-up study of 116 Type 1 (insulin-dependent) diabetic patients on long-term continuous subcutaneous insulin infusion was conducted after 4.5 +/- 0.2 years. The average HbA1c-value of these patients decreased by 1% to 6.7 +/- 0.1% during this observation period. Typical side effects of continuous subcutaneous insulin infusion such as skin inflammation at the catheter insertion site occurred with similar frequency as has been reported previously by other authors. Diabetic ketoacidosis (0.14 per patient year) and disabling hypoglycaemia (0.1 per patient year, including 0.05 hypoglycaemic coma per patient-year) occurred at substantially lower rates than in other comparable studies with Type 1 diabetic patients at a similar degree of metabolic control. Subgroup evaluation suggested that a normal (less than 5.6%) HbA1c-value at follow-up was associated with increased incidence of disabling hypoglycaemia, whereas poor metabolic control (HbA1c greater than 7.5%) was associated with increased rates of skin complications and hospital treatment for ketoacidosis. Thus, under the policies of this diabetes centre, continuous subcutaneous insulin infusion has proved to be beneficial to a large proportion of experienced adult Type 1 diabetic patients, who voluntarily had opted for, and continued with, this particular mode of insulin treatment.

Continuous insulin infusion

A major new approach to the improvements of metabolic control in insulin-dependent diabetic patients is the replacement of insulin by delivery systems which simulate non-diabetic insulin secretory patterns. In the last ten years a number of open-loop, extracorporeal, portable infusion pumps have been used in research trials tasting from a few days to several years. Routine treatment by insulin pumps is now being considered. Most infusers are syringe-drivers, although peristaltic and reciprocating pumps have also been employed. All are based on a slow, basal delivery rate, supplemented by insulin boosts at meal-times. The most popular infusion route is via the subcutaneous tissue. Technological development is concentrating on miniaturisation, alarms (such as low battery state and motor over-run) and more flexible/programmable delivery rates.

Attempts are in progress to ‘close the loop’ using an implanted glucose sensor. Most electrodes are amperometric or potentiometric enzyme sensors employing immobilised glucose oxidase. Encouraging in vivo results are being obtained from a novel amperometric biosensor which uses ferrocene to mediate electron transfer. The most likely implantation site is the subcutaneous tissue.

Insulin pump therapy for older adults: case report

Pump therapy offers some people with insulin-treated diabetes a way to achieve stricter blood glucose con trol and more flexible lives. While strict control may be most important for young people, older adults may benefit from the freedom possible with pump therapy. This case presentation describes the use of an insulin pump by a 68-year-old man whose main goal was to have more flexibility in his meal frequency and timing. Some special con siderations for pump therapy in older adults in clude the use of a sim pler, less expensive in sulin pump, visual aids, and less strict blood glucose targets.

Experience of continuous subcutaneous insulin infusion in the outpatient management of diabetic teenagers

Of forty-five adolescent diabetic patients offered continuous subcutaneous insulin infusion (CSII) as part of a large feasibility study, 13 (28.9%) initially chose the treatment, but only 4 out of 11 who actually started CSII continued for one year (64% discontinuation rate). In contrast 30.4% of adults approached chose CSII, and 32% had discontinued after one year. Improvement in glycaemic control was poor, and clinical problems were more common in pump-treated teenagers than in adults. CSII does not appear to be a therapeutic solution for adolescents having difficult management problems.

Frequency of diabetic ketoacidosis and hypoglycemic coma during treatment with continuous subcutaneous insulin infusion. Audit of medical care

The frequency of diabetic ketoacidosis and hypoglycemic coma in a large series of patients with insulin-dependent diabetes treated by long-term continuous subcutaneous insulin infusion was compared with the frequency of these events in a matched group of patients treated by conventional insulin injections at the same hospital over the same period of time. Ketoacidosis and hypoglycemic coma occurred no more frequently in continuous subcutaneous insulin infusion-treated patients. Therefore, intensified insulin therapy achieved by continuous subcutaneous insulin infusion does not appear to be associated with a greater risk of ketoacidosis or hypoglycemic coma than does conventional insulin therapy.

Severe hyperkalaemia and ketoacidosis during routine treatment with an insulin pump

During a feasibility study of the use of insulin pumps to treat diabetes ketoacidosis occurred at a rate of 0.14 episodes/patient/year in the first year but was lower in subsequent years. A case of cardiac arrest secondary to hyperkalaemia during ketoacidosis occurred in a patient treated with a pump. The mean (SD) serum potassium concentration on presentation to hospital with ketoacidosis was significantly higher in patients treated with a pump (5.7 (1.1) mmol(mEq)/l) than those treated with conventional injections of insulin (4.9(0.9) mmol/l; p less than 0.01). The high rate of ketoacidosis and raised serum potassium concentrations during treatment with the pump creates doubt about the use of this treatment as an alternative regimen for large numbers of patients in a busy diabetic clinic.

Clinical applications of infusion systems

Continuous delivery of drugs from portable and implantable pumps offers several advantages over intermittent therapy, including control and maintenance of blood levels of the drug within a narrow therapeutic range, and increased predictability of response. Clinical applications are discussed in the areas of diabetes mellitus, infertility and delayed puberty, iron overload, anticoagulation, analgesia, prevention of premature labour, cardiac arrhythmias, dissolution of gallstones and anticancer therapy.