Subcutaneous glucose monitors are becoming increasingly common in the monitoring and management of glucose for diabetics.
The majority of these are unlikely to impact routine imaging but are important to consider in MRI.
In the UK, the commonest device available on prescription is the FreeStyle Libre Flash system. This sits on the skin, about the size of a milk bottle top, with a small cannula monitoring interstitial fluid glucose. Other systems are available, some working in conjunction with insulin pumps.
These devices are currently MRI unsafe (January 2019) 2; with metallic components in contact with skin. The Libre is reapplied every 14 days, with an adhesive designed to last that long. MR examinations should ideally be timed later in this period to preserve patient skin and maximize sensor function.