Transient Benign Ketosis Is Common in Type 1 Diabetes During Very-Low Carbohydrate States: Novel Data from Continuous Ketone Sensor

Objective: Continuous ketone sensors have the potential to reduce diabetic ketoacidosis in type 1 diabetes. We evaluated the accuracy of a novel ketone sensor and quantified physiological ketone metrics during ketogenic diets in type 1 diabetes. Research Design and Methods: Adult participants on automated insulin delivery wore SiBio continuous ketone sensors and underwent two 6-day ketogenic diets, in random order. The two diets were very-low carbohydrate (<50 g/day) and intermittent 12-h fasting. Between the two diets, participants were admitted for a 6- to 8-h insulin suspension experiment to assess sensor accuracy. Ketone sensor readings were compared with capillary levels by FreeStyle Libre 2 meter. Results: Sixteen participants completed the study (age 36.5 [17.0] years, HbA1c 7.0% [0.6], insulin dose 0.72 [0.26] units/kg) and provided 870 sensor-meter paired data points. The mean absolute difference (MAD) for ketone values <0.6 mmol/L was 0.1 (0.1) mmol/L and the relative MADs for ketone values ≥0.6 and ≥1.0 mmol/L were 24.2% (17.1) and 19.6% (13.3), respectively. During the ketogenic diets (155 days), there were 81 ketosis events (3.7 events/week) ≥0.6 mmol/L of more than 15 min, with a median duration of 60 (30–105) min/event. All ketosis events except one were asymptomatic. Glucose levels, basal insulin delivery, and time of the day were not related to ketosis events. Conclusions: SiBio ketone sensor demonstrated preliminary accuracy and reveals that benign, transient ketosis are common in type 1 diabetes during very-low carbohydrate states. This has implications on the utility of continuous ketone sensors in clinical practice. Trial Registration: Clinicaltrials.gov NCT06420518.