Steady glucose screens have remodeled life for many individuals with kind 1 diabetes. As an alternative of counting on finger-prick blood checks all through the day, customers can monitor their blood sugar ranges nearly constantly. This enables them to obtain alerts by way of a smartphone when ranges turn out to be too excessive or too low and spot patterns that assist them higher handle their situation.
However the latest research from my colleagues and I has uncovered a little-known blind spot. Throughout essentially the most excessive excessive and low blood sugar episodes, these units can not inform customers precisely how extreme these occasions are. Whereas this limitation doesn’t have an effect on the usual measures medical doctors use to evaluate diabetes administration, it does imply that some vital info is misplaced when blood sugar strikes past the monitor’s measurement vary.
Steady glucose screens are small sensors, normally worn on the higher arm, that measure glucose ranges each jiffy and ship the outcomes to a smartphone app. They’ve revolutionised diabetes care over the previous decade by giving individuals a a lot clearer image of how their blood sugar responds to meals, train, sleep and insulin.
Like each scientific instrument, nonetheless, they’ve limits. They’ll solely measure blood sugar inside a set vary. If blood sugar rises or falls past that vary, the sensor can inform you that ranges are extraordinarily excessive or extraordinarily low, however it will possibly now not say precisely how excessive or how low they’re.
A helpful comparability is a kitchen thermometer that solely measures as much as 100°C. As soon as the temperature exceeds that time, the thermometer can inform you it’s at the least 100°C, however not whether or not it’s 120°C or 180°C. Steady glucose screens work in a lot the identical method when glucose strikes past their measurement vary.
What we discovered
To learn how typically this truly occurs, we analysed practically 47 million publicly accessible steady glucose monitor readings from 948 individuals with kind 1 diabetes throughout 4 massive worldwide scientific trials.
Between 93.5% and 100% of contributors throughout the 4 research skilled at the least one studying that reached the higher or decrease measurement restrict. In different phrases, that is one thing that impacts nearly everybody with kind 1 diabetes who makes use of these units over a time frame.
The sample was significantly hanging for top glucose ranges. In three of the 4 research, greater than one-third of those episodes remained on the higher measurement restrict for at the least an hour. The longest episode for a typical participant lasted between two and three hours. All through these durations, the monitor may affirm that blood sugar was extraordinarily excessive, but it surely couldn’t distinguish between ranges simply above its restrict and people who had been considerably increased.
The sample wasn’t evenly distributed both. Youthful individuals skilled upper-limit readings extra continuously than older adults. This displays what we already know in regards to the challenges of managing blood sugar throughout adolescence.
We additionally discovered that folks with increased HbA1c ranges (a blood take a look at that displays common blood sugar over the earlier two to 3 months) had been more likely to succeed in the monitor’s measurement limits. In easy phrases, those that already battle most to handle their diabetes are additionally the individuals most certainly to come across this hidden limitation.
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Reassuringly, this limitation doesn’t seem to undermine the figures that medical doctors depend on in on a regular basis diabetes care. We in contrast steady glucose monitor readings with simultaneous finger-prick blood glucose measurements.
We discovered that even when sensors usually reached their measurement limits, the usual abstract measures utilized in scientific observe remained remarkably sturdy. Metrics akin to common glucose ranges, glucose variability and time in range (the proportion of the day spent throughout the goal glucose vary) had been largely unaffected.
That’s in all probability as a result of, even amongst contributors with comparatively frequent glucose readings that meet or exceed measurement limits, most readings nonetheless fell comfortably throughout the sensor’s measurable vary. So, the principle consequence isn’t inaccurate abstract statistics, however a lack of element throughout essentially the most excessive glucose occasions. We all know glucose could be very excessive or very low, however we can not inform precisely how excessive or how low.
What ought to change?
Present smartphone apps and web-based software program summarise glucose information in many various methods. However they by no means explicitly state {that a} sensor has reached its measurement limits, how typically this occurred or how lengthy it lasted.
Including that info would wish solely a comparatively small change to present software program. However that might assist medical doctors and researchers determine the individuals for whom this blind spot is most related and interpret glucose information with larger confidence.
Steady glucose screens stay one of the vital advances in diabetes care. Our findings shouldn’t discourage anybody from utilizing them. Each scientific instrument has a measurement vary. Understanding these limits helps us make higher use of the knowledge it offers. Recognising when a glucose sensor has reached the sting of what it will possibly reliably measure is one other step in direction of making an already transformative expertise much more helpful.
