1 files changed, 10 insertions, 0 deletions

diff --git a/glucometerutils/support/freestyle.py b/glucometerutils/support/freestyle.py
index 816af81..d18a81f 100644
--- a/glucometerutils/support/freestyle.py
+++ b/glucometerutils/support/freestyle.py
@@ -64,6 +64,16 @@ def _verify_checksum(message, expected_checksum_hex):
     if expected_checksum != calculated_checksum:
         raise exceptions.InvalidChecksum(expected_checksum, calculated_checksum)
 
+def convert_ketone_unit(raw_value):
+    """Convert raw ketone value as read in the device to its value in mmol/L.
+
+    As per
+    https://flameeyes.github.io/glucometer-protocols/abbott/freestyle-libre.html
+    this is actually not using any mg/dL→mmol/L conversion, but rather the same
+    as the meter uses for blood glucose.
+
+    """
+    return raw_value / 18.0
 
 class FreeStyleHidDevice(hiddevice.HidDevice):
     """Base class implementing the FreeStyle HID common protocol.