A red rash on the leg requires a rethink

A patient’s poor diabetes control is thought to be linked to a red patch on his shin, though not via mechanisms that first glance might suggest

Mike, a 51-year-old Caucasian male, presents to his GP with a two-week history of right lower leg rash (see figure 1).

He has no other symptoms.

Mike has type 2 diabetes (T2DM), which is poorly controlled on insulin glargine. HbA1c one month ago was 10.1%, self-monitored fingerprick fasting glucose is typically 10-14mmol/L and postprandial glucose 16-22mmol/L. 

His past medical history includes previous alcohol dependence now in remission, GORD, alcoholic hepatitis, depression, and diffuse idiopathic skeletal hyperostosis (Forestier’s disease).