Dexcom CGM users to have clearer way of understanding trend arrows

A new method allows young people and adults with type 1 diabetes to better understand and make better use of trend arrow data from the Dexcom G5 mobile continuous glucose monitor (CGM) for adapting insulin doses.

The Dexcom G5 CGM displays trend arrows indicating whether blood glucose levels are rising or falling, and how fast this is happening. Previously published methods on how best to use this data to adjust insulin doses were deemed imperfect and/or not user-friendly.

Two recent studies, conducted by researchers from Harvard Medical School and Feinberg School of Medicine, describe a more personalised system built upon basic algorithms that CGM users could more easily get their heads around.

The new system uses the rate of change for each trend arrow scenario, in combination with predicted glucose levels and the correction factor, to determine how the insulin dose should be adjusted.

The novelty of their approach lies in the consideration of different insulin sensitivities, mostly based on age. The lower the sensitivity to insulin, the greater the recommended dose adjustment would be in response to an upward trend arrow, for example.

For each insulin sensitivity range, the method provides dose adjustments that are expressed in insulin units, rather than percentages or other corrective values, to simplify calculations for CGM users.

The experts created one table of insulin dose adjustments for adults and a separate one for children and teens. These tables may be used by people on multiple daily injections as well as those using an insulin pump.

Making better use of trend arrow data could be especially useful for people with hypo unawareness or at risk of severe hypos, as well as those who have difficulty staying within target range. 

The data-sharing capability of the Dexcom G5 will also make it simpler for healthcare professionals to help users to better adjust their insulin doses based upon the interpretation of trend arrows.

Researchers highlighted that this approach to insulin dose adjustment is not meant to replace standard calculations but to refine them. People should get attuned to using basic CGM data first before moving onto adjusting insulin dose using trend arrows. 

The findings related to the use of this new method in children and adults were both published in the Journal of the Endocrine Society.