Endocrine Abstracts

Background: Continuous glucose monitoring (CGM) measures interstitial glucose and display trends arrows, showing the direction and rate of change in glucose. Trend arrows allow the child/youth to take action to prevent hypo- and hyperglycaemia. Effective strategies for adjusting insulin boluses for trend arrows are lacking. The JDRF CGM Study Group recommended a 10/20% increase/decrease in the insulin dose. However this formula requires a mathematical calculation with each trend arrow, limiting the tool’s uptake in paediatrics. We developed an alternative tool, based on the patient’s insulin sensitivity factor.

Objective and hypothesis: To compare the effect of the trend arrow adjustment tool, the 10/20% adjustment and no adjustment for arrows; on postprandial glucose. To evaluate patient satisfaction and ease of use of both adjustment methods.

Method: A single blinded, counterbalance, treatment assignment crossover study of 20 subjects with type 1 diabetes. During a hospital assessment trend arrows were induced through exercise or oral carbohydrate. Subjects consumed a standardised meal with the insulin dose adjusted for trend arrows using the assigned method. Subjects used the assigned method during week 1, made no adjustment for arrows in week 2 and used the alternative method in week 3. CGM data was used to analyse postprandial glucose.

Results: Time with postprandial glucose in target range was equivalent with the trend arrow adjustment tool and the 10/20% adjustment. There was a trend towards more time in target range and less hypoglycaemia, with use of either tool compare to ignoring the arrows. Significantly more errors were made using the 10/20% method. Satisfaction and ease of use was greatest with trend arrow adjustment tool.

Conclusion: The trend arrow adjustment tool is a simple and well received method of adjusting insulin boluses for CGM trend arrows, which can be successfully used in the paediatric population.