When these symptoms occur, the first step should be to measure the blood glucose level. If the diagnosis of diabetes is established, it is likely to be an early symptom of diabetic foot; in addition, if the skin around the thumb is visibly ischaemic, necrotic and severely oedematous, peripheral vascular disease is likely; if the ulceration and peeling is accompanied by significant itching and oozing with an unpleasant odour, it is likely to be the result of a fungal infection.