Two diabetic patients presented in coma to the accident and emergency department. Although they were hypoglycaemic, the initial blood glucose reagent strip readings were high. We postulate that glucose contamination of their fingers occurred and resulted in spuriously high readings. A small survey highlights the problems resulting from such contamination. Correct handling of blood glucose reagent strips is stressed and we advise venous blood samples in all diabetic emergencies presenting to the accident and emergency department.