Key result
At rest, CGM sensor placement on the arm better reflected capillary glucose than placement on the leg (MARD 12.4% vs 18.3%, P=0.02), but accuracy was similar between sites during cycling exercise.
Why the study?
To evaluate whether continuous glucose monitoring sensors worn on active muscle provide enhanced insight into glucose control during cycling exercise compared with traditional arm placement in non-diabetic individuals.
Does CGM sensor placement on the leg improve glucose monitoring accuracy compared to the arm during exercise in healthy non-diabetic participants?
Does CGM sensor placement on the leg improve glucose monitoring accuracy compared to the arm during exercise in healthy non-diabetic participants?
Absolute Event Rate: 18.3% vs 12.4%
p-value: p=0.02
While traditional arm placement of CGM sensors is more accurate at rest, leg placement offers similar accuracy during cycling and may provide better insight into working muscle glucose concentrations.
Arm placement may improve resting CGM accuracy versus leg; leaves open optimal site selection during exercise.
The purpose of this investigation was to evaluate whether continuous glucose monitoring (CGM) sensors worn on the active muscle may provide enhanced insight into glucose control in non‐diabetic participants during cycling exercise compared to traditional sensor placement on the arm. Data from 9 healthy participants (F:3) was recorded using CGM sensors on the arm ( triceps brachii ) and leg ( vastus medialis ) following 100 g glucose ingestion during 30 min experimental visits of: resting control, graded cycling, electrically stimulated quadriceps contractions, and passive whole‐body heating. Finger capillary glucose was used to assess sensor accuracy. Under control conditions, the traditional arm sensor better reflected capillary glucose, with a mean absolute relative difference (MARD) of 12.4 ± 9.3% versus 18.3 ± 11.4% in the leg ( P = 0.02). For the intended use during exercise, the sensor‐site difference was attenuated, with similar MARDs during cycling (arm:15.5 ± 12% versus leg:16.7 ± 10.8%, P = 0.96) and quadriceps stimulation (arm:15.5 ± 14.8% versus leg:13.9 ± 9.5%, P = 0.9). At rest, glucose at the leg was consistently lower than the arm ( P = 0.01); whereas, during graded cycling, the leg‐glucose was lower only after maximal intensity exercise ( P = 0.02). There was no difference between sensors during quadriceps stimulation ( P = 0.8). Passive heating caused leg‐skin temperature to increase by 3.1 ± 1.8°C versus 1.1 ± 0.72°C at the arm ( P = 0.002), elevating MARD in the leg (23.5 ± 16.2%) and lowering glucose in the leg ( P < 0.001). At rest, traditional placement of CGM sensors on the arm may best reflect blood glucose; however, during cycling, placement on the leg may offer greater insight to working muscle glucose concentrations, and this is likely due to greater blood‐flow rather than muscle contractions.
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Coates et al. (2023) studied Healthy non-diabetic (n=9). CGM sensor placement on the leg (vastus medialis) vs. CGM sensor placement on the arm (triceps brachii) was evaluated on Mean absolute relative difference (MARD) compared to finger capillary glucose under control conditions (p=0.02). At rest, CGM sensor placement on the arm better reflected capillary glucose than placement on the leg (MARD 12.4% vs 18.3%, P=0.02), but accuracy was similar between sites during cycling exercise.
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