The Free Living Ketone Profile Study

An Investigation of Ketone Profiles in Community-Dwelling Adults with Type 1 Diabetes Using Continuous Ketone Monitoring

This study used a new wearable continuous ketone monitor (CKM), alongside a continuous glucose monitor (CGM), to record ketone levels continuously for two weeks in 64 adults with type 1 diabetes living in the community. The aim was to understand how often and when ketone rises occur in people who are generally well and not taking SGLT inhibitor drugs.

Adults with type 1 diabetes wore a CKM and a CGM for approximately two weeks. Participants were grouped by their highest ketone reading over that period: always <0.6 mmol/L, peak 0.6–0.9 mmol/L, or peak ≥1.0 mmol/L. A short diary was kept by participants to record symptoms and activities during the monitoring period.

Most people (61%) had ketone levels consistently below 0.6 mmol/L over the two weeks. A further 23% had at least one reading of 0.6–0.9 mmol/L and 16% had at least one reading ≥1.0 mmol/L. Episodes of elevated ketones were generally uncommon, brief and without symptoms; the typical episode lasted under an hour, although the longest recorded episode lasted a few hours. Elevated ketones tended to occur most often in the early morning (around 04:00–06:00), but mild daytime rises were also sometimes observed. When ketones were ≥1.0 mmol/L, average glucose levels were higher (about 47 mg/dL higher) than during matched periods with low ketones, yet glucose measurements alone were not a reliable substitute for measuring ketones. Participants reporting lower daily carbohydrate intake were more likely to have higher ketone readings, consistent with known effects of carbohydrate restriction.

Continuous ketone monitoring provides a clearer picture of real-life ketone patterns that point-of-care checks may miss. In this study, most well, free-living adults with type 1 diabetes (not taking SGLT inhibitors) rarely developed ketone levels ≥1.0 mmol/L, suggesting this threshold might be a reasonable starting point for CKM alert settings, although formal guidance is not yet established. CKM may help detect rising ketones early and could serve as a useful complement to CGM, particularly for preventing diabetic ketoacidosis (DKA) in higher-risk situations.

This was a small study (64 participants) with only two weeks of monitoring, which limits generalisability. Participants were aware they were being monitored, which might have influenced behaviour. The study also excluded people taking SGLT inhibitors and those on very low-carbohydrate diets.

Larger and longer studies are needed to define safe and actionable CKM alarm thresholds, to better identify who is most at risk of problematic ketone rises, and to guide clinical use of CKMs alongside glucose monitoring.

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