The goal of this 14-day randomized pilot trial is to assess the accuracy of a continuous ketone monitoring (CKM) system when compared to standard point-of-care capillary ketone monitors in individuals with type 1 diabetes on insulin pump therapy. The main question it aims to answer is:

- Can a CKM system demonstrate equivalent ketone monitoring compared to a capillary ketone monitor with accuracy within a mean absolute difference of no more than ± 0.1 mmol/L.

Participants will be asked to wear the SiBio KS1 CKM system for 14-days while undergoing two sequential ketogenic diets which are interspaced by an inpatient insulin-suspension period.

In this study, all study participants will wear the CKM system and collect multiple standard point-of-care capillary ketone measurements. Therefore, there will be two groups in terms of measurements methods, one acting as an active comparator (the CKM system) and, the other serving as a control (point-of-care capillary ketone measurements). Both groups of measurement methods will be assessed in all study participants for both the outpatient phase (sequential ketogenic diets) and, the inpatient phase (insulin-suspension period) of the study to evaluate the accuracy of the CKM system.

Inclusion Criteria:

1. Adults ≥ 18 years of age.
2. A clinical diagnosis of type 1 diabetes (T1D) for at least one year, as per their treating diabetes physician in agreement with the primary investigator's clinical judgment (confirmatory C-peptide and antibodies will not be required).
3. On stable, commercial closed-loop pump therapy for the past 30 days.
4. Stable use of continuous glucose monitor system for the past 30 days.
5. Cellular phone with Android OS operating system 8.1 and above or iOS11 and above operating system, for data compatibility with continuous ketone monitor mobile app (SiCKM app).
6. Able to perform study related tasks.

Exclusion Criteria:

1. Current or ≤ 2 weeks use of sodium-glucose cotransporter-2 (SGLT2) inhibitor medication (e.g. empagliflozin).
2. Current use of ascorbic acid (Vitamin C) as it may impair accuracy of the sensor.
3. Severe hypoglycemic episode within one month of admission, defined as an event where glucose was <4 mmol/L resulting in seizure, loss of consciousness, needing third party assistance, or need to present to the emergency department.
4. Diabetic ketoacidosis episode requiring medical attention or intravenous insulin within one month.
5. Planned or ongoing pregnancy or breastfeeding individuals.
6. Any serious medical or psychiatric illness likely to interfere with ability to complete the trial, as per judgement of investigators.

The population of this study are individuals with a type 1 diabetes diagnosis exceeding 1 year, using insulin pump therapy for more than one month. Participant recruitment for the study will predominantly occur through the Hygea Medical Clinic, complemented by outreach to previous study participants who have consented to future contact for research opportunities.

The raw data (that is, insulin delivery, glucose levels and individual participant data) and informed consent form will be shared by the corresponding author, for academic purposes, subject to a material transfer agreement and approval of the McGill University Health Center's Research Ethics Board. All data shared will be de-identified. Raw data will be shared for non-commercial use upon reasonable request and a material transfer agreement.