Quality Standards for Diabetes Care Toolkit

Insulin pumps and continuous glucose monitoring systems

Insulin pumps

Continuous subcutaneous insulin infusion (CSII) or insulin pumps are small battery powered external devices that deliver insulin through an infusion line into the skin by a removable cannula. They are programmed to deliver a continuous low rate of insulin during the day and night (basal) with additional insulin being delivered (as a bolus dose) at mealtimes or to correct a high blood glucose level. At snack and mealtimes (whenever food is eaten), the user enters the amount of carbohydrate into their pump as well as their blood glucose level and the pump calculates how much insulin is needed for the food and to achieve the target blood glucose level (Starship Children’s Health).
A review of the literature around the effectiveness and economy of insulin pump therapy was commissioned by the Ministry of Health and performed by the Health Services Assessment Collaboration at the University of Canterbury (Campbell et al 2008). They concluded that ‘when compared with optimised MDI [multiple daily injections], CSII results in a modest but potentially worthwhile improvement in glycosylated haemoglobin levels in all patient groups assessed (ie, adults with type 1 diabetes, children and adolescents with type 1 diabetes, and adults with type 2 diabetes). Due to the short duration of the clinical trials is not possible to evaluate the longer term benefits of such a difference in HbA1c levels; however, there is an expectation that it would be reflected in a reduction in long term complications. Although more immediate primary benefits from CSII may be associated with an impact on the incidence of severe hypoglycaemic events and improved quality of life (through greater flexibility of lifestyle), there is limited evidence to support this from the studies identified in this update.
However, despite the limited evidence it is postulated that CSII may reduce the number of severe hypoglycaemic attacks a patient experiences compared with MDI. According to the results of the cost-effectiveness analysis conducted herein, it is estimated that if every patient who changed from MDI to CSII therapy was able to avoid one severe hypoglycaemic attack every two years (ie, an improvement of 0.5 events per annum), the incremental cost per severe hypoglycaemic event avoided would be approximately $6,000. The total incremental cost associated with the introduction of CSII compared to MDI for a patient with type 1 diabetes is approximately (in 2008) $16,000 over six years (the approximated life of the pump)’ (p vi).
Goenka et al (2011) note that there will be an increase in the uptake of insulin pump use for people with type 1, estimates in the UK being 10% of those aged over 12 years and 25% of those under 12. Consequently, the initiation and management of pumps should be an integral part of a Diabetes Specialist Service and should involve a multidisciplinary team trained in pump management. The team should include staff with a special interest in insulin pump therapy and clinical, psychological and educational expertise.

Continuous glucose monitoring systems (CGMS)

Continuous glucose monitoring systems (CGMS) measure blood glucose levels semi-continuously. Most modern CGMS consist of a small needle which is inserted in the abdominal subcutaneous fat. The tip of the needle houses a small glucose sensor which can measure glucose levels in the fluid which surrounds the fatty tissue.
A Cochrane review of CGMS for type 1 diabetes mellitus (Langendam et al 2012) included 22 studies in which a total of 2883 patients were randomised to receive a form of CGM or to use self-measurement of blood glucose using fingerprick. The follow-up period ranged from three to 18 months with most studies reporting results for six months of CGM use. This review shows that CGM helps in lowering HbA1c. In most studies, the HbA1c value decreased in both the CGM and the self-monitoring of blood glucose (SMBG) users but more in the CGM group. The difference in change in HbA1c levels between the groups was on average 0.7% for patients starting on an insulin pump with integrated CGM and 0.2% for patients starting with CGM alone. The most important adverse events, severe hypoglycaemia and ketoacidosis, did not occur frequently in the studies and absolute numbers were low (9% of the patients measured over six months).
The American Diabetes Association (ADA) recommendations (ADA 2014) state that when used properly, continuous glucose monitoring (CGM) in conjunction with intensive insulin regimens is a useful tool to lower HbA1c in selected adults (aged ≥25 years) with type 1 diabetes. Although the evidence for HbA1c lowering is less strong in children, teens, and younger adults, CGM may be helpful in these groups. Success correlates with adherence to ongoing use of the device. CGM may be a supplemental tool to SMBG in those with hypoglycaemia unawareness and/or frequent hypoglycaemic episodes.