A phenomenon called "white coat hypertension" has been recognized for a number of years in the general population. It refers to the tendency of a person to have increased blood pressure readings in the presence of a healthcare professional, i.e., someone wearing a white coat. This response leads to a diagnosis of hypertension in people who do not, in fact, have high blood pressure, and to the initiation of treatment in people who don't need it.

It is defined when 24-hour ambulatory blood pressure reveals normal blood pressure over the course of a day. There are estimates that white coat hypertension affects from 24% to 39% of the general hypertensive population. Research into people with type 2 diabetes has produced widely variable findings, with estimates ranging from 23% to 62%. A Spanish study found that fully three-quarters of patients with type 1 diabetes newly diagnosed with hypertension were, in fact, not hypertensive according to 24-hour ambulatory BP monitoring.

The authors suggest that 24-hour ambulatory blood pressure monitoring be performed in all diabetic patients after the diagnosis of hypertension in the doctor's office to avoid the unnecessary treatment of some patients.