Page 277 - Glucose Monitoring Devices

284 CHAPTER 14 Predictive low glucose suspend systems

Keys to clinical use
Patient success with PLGS technology is inherently tied to successa maintaining a
CGM and insulin infusion site. Thus the first steps to successfully relate to proper
skincare. Some patients may have no problems properly maintaining the devices
with minimal skin irritation, while for many, particularly pediatric patients, skincare
will be the major barrier to success. Our center has previously published comprehen-
sive guidelines on skincare for chronic device use [66]. For patients with allergies to
the adhesives, we generally recommend off-label use of nasal steroids applied topi-
cally (e.g., fluticasone). We also recommend the use of protective barrier films. For
removal, we recommend the use of adhesive removers and a slow low angle folding
back of the adhesive tape [66].
Beyond tolerance of the on-body devices, optimization of CGM accuracy is
essential to proper PLGS function. Thus, for sensors such as the Medtronic Guard-
ian Sensor 3 which still requires periodic calibration, we recommend calibrating
about three times per day, generally when the CGM signal is flat (i.e., trend arrows
show less than 1 mg/dL/min of change) and not while the patient is hypoglycemic.
Fingerstick reference values should be performed on hands washed with soap and
water and then fully dried, and with an accurate glucose meter with a MARD
of <10% [29]. For factory calibrated CGMs such as the Decom G6, we do not
recommend additional calibrations as BG meter values may be less accurate
than factory-supplied calibrations. We do however advise the patient to not extend
sensor life beyond the approved period as this may strongly decrease sensor
performance [67].
As insulin suspension to prevent hypoglycemia is intended to replicate normal
physiology, we do not view system suspensions as a sign of a problem, but rather
a normal aspect of diabetes care. When reviewing device downloads for patients
using PLGS technology, it is not uncommon to see 4e8 suspension events per
day. If the suspensions are occurring at varied times, we do not generally recom-
mend adjusting pump settings to prevent suspensions from occurring. If, however,
suspensions tend to occur after a similar event consistently, such as 2 h after a
hyperglycemia correction or 2 h after a certain meal bolus, it may be beneficial to
alter pump settings around that event. To avoid rebound hyperglycemia, we also
educate patients that following an hour of insulin suspension, often the treatment
of hypoglycemia is not required [54].
A more common trend among PLGS users is the request to increase insulin pump
dosing after starting this technology. Many patients have reported that with
increased confidence in these systems to prevent hypoglycemia, they feel more
comfortable being aggressive at minimizing hyperglycemia with their preprog-
rammed basal rates, insulin-to-carbohydrate ratios, and even correction dosing.
These changes should obviously be made cautiously and with the guidance of
trained diabetes experts. Such adjustments, however, may help improve time in
the target range and reduce HbA1c, as automation reduces hypoglycemia exposure
in patients using PLGS technology.