Feasibility Study of a Combined Glucose and Ketone Sensor in People with and without Diabetes

Participants enrolled at St Vincent's Hospital Melbourne will continuously wear a combined glucose and ketone monitor (CGKM) over 72 hours under free-living conditions. Standardized meal and ketone drink tests in the clinical trial centre including frequent blood sampling will be performed on Day 1 (the day of sensor insertion) and Day 4 (the final day of study). All sensor data will be masked to participants and total duration of sensor wear and persistence of sensor signal will be monitored throughout the intervention. The prototype CKGM device consists of a sensor probe inserted transcutaneously and an optoelectronic wireless wearable (OEW) device connected to the inserted probe and placed on the surface of the skin, aligned above the inserted probe. The CKGM measures interstitial ketones (beta-hydroxybutyrate) and glucose directly, as well as oxygen partial pressure, which is used as a reference measurement to correct collected ketone and glucose values. On the first and last day of CGKM wear, a standardised test meal containing 65g carbohydrate will be consumed by each participant. Participants with diabetes will administer half their usual insulin dose using either an injection or an insulin pump immediately prior to the meal. Venous blood glucose (study meter and YSI) and ketones (meter) levels will be measured immediately following sensor insertion (baseline) and every 15min following the test-meal for four hours. Three hours following the meal test, participants will ingest a ketone ester drink (at ~12:00PM - 573mg/kg of ketone ester in ~100mL water/solution). Venous blood samples for glucose and ketones will be collected at 15-minute intervals until the end of the study visit, which will occur 120 min after the ketone drink has been ingested (~2:00PM).