Endocrine Abstracts

The benefits of continuous subcutaneous insulin infusion (CSII, insulin pump therapy) in type 1 diabetes, compared to multiple dose insulin injections (MDI), include a reduction in HbA1c, the frequency of all grades of hypoglycaemia, insulin dosage and glycaemic variability, and improved patient satisfaction with therapy and improved quality of life. The evidence base for this is now well established from meta-analyses of randomised controlled trials (RCTs) and from clinical observation over more than 30 years. Improvements occur in both adults and children. The greatest improvements are in those worst controlled on injection therapy. The best and most cost effective use of CSII in adults is therefore probably in those who have failed to achieve acceptable glycaemic control with MDI and structured diabetes education. CSII is approved by NICE for use in children <12 years of age without them having first ‘failed’ on CSII, though the evidence for pumps as the best first-line therapy in children is still emerging.

An important contributor to HbA1c and glycaemic variability in diabetes is the postprandial rise in blood glucose and research with insulin pumps in recent years has seen attempts to reduce this by several strategies, including integrated bolus calculators, administration of the meal-time insulin bolus about 15 min before rather than at the time or after eating, improved attention to carbohydrate counting (and possibly also fat and protein counting), identification of missed meal boluses from computer downloads, and the use of square- or dual-wave boluses for fatty or high-protein meals. Much of the evidence for these new strategies comes from research in children with diabetes.

Modern insulin pumps have the potential for continuous glucose monitoring (CGM) connectivity (and CGM can be used with MDI), and there is strong evidence from RCTs that HbA1c and exposure to mild-to-moderate hypoglycaemia is reduced in the worst controlled patients and in those who use sensors frequently. Children benefit as much as adults, providing they use the sensor often. The effects of CGM on severe hypoglycaemia and quality of life are uncertain, as well designed RCTs have not been reported yet. Low-glucose suspend (LGS) insulin pumps are now available, where the basal rate of the pump is suspended for a period when the sensor-monitored glucose falls below a preset threshold, thereby allowing glucose to return into the target range. LGS pumps reduce the duration of hypoglycaemia in adults and children with type 1 diabetes, though RCT evidence for effects on severe hypoglycaemia frequency is still awaited.