Performance of a new real-time continuous glucose monitoring system: a validation study of the Medtrum TouchCare Nano 14 CGM System

Accurate glucose measurements are of utmost importance in the management of
type 1 diabetes mellitus (T1DM). These results are used to make decisions
concerning insulin dose. Next to self-measurement of blood glucose (SMBG) with
finger pricks, continuous glucose measurements (real-time or
intermittent/flash) with sensors have emerged as valuable options for glucose
estimates. In the past decade, a variety of options for continuous glucose
monitoring (CGM) have become available. For many users, this opportunity for
continuous and automatically readable glucose readings is a big step forward.

CGM systems measure interstitial fluid glucose levels at rather closely spaced
intervals to provide semi-continuous information on glucose levels, allowing
identification and signalling of glucose level fluctuations to a degree that
cannot be obtained with intermittent capillary blood glucose measurements.
While improved glycemic control has been demonstrated with the use of CGM
systems, CGM accuracy also remains a challenge; many of the available systems
need calibrating at least twice daily to allow a sufficiently reliable
correlation between interstitial and capillary glucose results.

Whenever a new CGM device becomes available, it is essential to critically
evaluate its accuracy and usability. This also will be necessary for the
Medtrum TouchCare Nano 14 CGM System. This system uses a small, soft and
transcutaneous glucose oxidase*based electrochemical glucose sensor (MD*JY*006)
to detect glucose levels in the interstitial fluid every 2 min over 7 days. It
has an one*point calibration algorithm. Independent accuracy assessments of the
recently introduced TouchCare A7+ CGM System are scarce, with only one
publication up to now (PMID: 28563974).

This study by Zhou et al. was performed among 63 Chinese persons, aged 18-70
years (mean 59 years), with diabetes (10 type 1 and 53 type 2 diabetes), BMI
24.7 kg/m2 and mean HbA1c 8.2 ± 1.7%. The TouchCare CGM system was worn for 7
consecutive days and on a randomized day venous blood samples were collected
(in clinic, for 7 h with venous blood collected every 15 min) as comparison to
CGM based glucose outcomes. A total op 1678 paired sensor-reference based
values were collected from 60 participants. The percentages of sensor values
that met the ±10%/10 mg/dL, ±15%/15 mg/dL, ±20%/20 mg/dL, ±30%/30 mg/dL, and
±40%/40 mg/dL deviation criteria were 65.7, 81.5, 90.5% (95% CI: 89.1-91.9%),
96.9 and 98.9%, respectively. The mean absolute relative difference (MARD) was
9.1 (8.9 to 9.2)%. there was no significant difference among the MARDs for the
7 days tested by the analysis of variance. In Clarke Error Grid analysis 99.1%
of the paired sensor-reference values fell within zones A and B (89.7% within
zone A and 9.4% within zone B). Just 15 (0.9%) paired sensor-reference values
fell within clinical risk zone D, which represents *dangerous failure to detect
and treat* errors. No paired sensor-reference values fell within zone C or E.

The presently proposed study is designed to further assess the accuracy and
usability of the TouchCare Nano 14 CGM system by comparing its scanned sensor
results with various standardized capillary reference methods and the results
obtained with a flash glucose monitoring system (FGM) in subjects with type 1
diabetes.

To establish the accuracy of the Medtrum TouchCare Nano 14 CGM system compared
to the
current gold standards i.e. established central laboratory technique (the
StatStrip Xpress®
monitoring system (Nova Biomedical, Waltham, WA), the accuracy of a flash
glucose monitoring (FGM) system (Free Style Libre) (FGM-FSL).

This study has a prospective design. Inclusion and study procedures will take
place at
the Department of Internal Medicine of the Isala hospital (Zwolle, the
Netherlands).

The overall study duration for each participant will be 14 days. After
obtaining informed consent, baseline characteristics (a.o. age, gender, body
mass index, waist circumference, diabetes duration, kind of insulin treatment
modality, use of other medication) will be collected using a standardized
case-record form during the first study visit.

Additionally, both a TouchCare Nano 14 CGM will be inserted in the abdominal
wall and the back of one of the upper arms. The FGM-FSL will be inserted in the
contralateral upper arm. All device related procedures will performed by one
trained investigator.

Out-of-hospital testing
Patients will be instructed to perform at least 4 capillary self-measurements
(preferably 7) with the StatStrip Xpress® monitoring system (Nova Biomedical,
Waltham, WA).

The preferred testing sequence will be at least upon waking, before lunch,
before dinner and at bedtime. It will be recommended to also confirm glucose
levels with a capillary measurement in case of (imminent and / or suspected)
hypoglycemia, glucose levels changing rapidly, or when symptoms do not match
the systems readings. All data available within the report systems will be
electronically collected from the source systems

A small needle is inserted through the skin and a small probe remains for 14
days. No further risks for the subject