High blood pressure (HBP), masked hypertension, and lack of nocturnal drop in BP numbers are common in patients with diabetes.In addition to spot measurement of BP in the office, ambulatory blood pressure monitoring (AB PM) is useful in diabetic subjects. It provides a greater number of BP measurements than the conventional office measurement. The major advantage of ABPM is that it allows the diagnosis of both white coat and masked hypertension.Masked hypertension is associated with a poor cardiovascular prognosis comparable to that of uncontrolled hypertension and a higher frequency of target organ damage compared with normal BP, and close to or higher than that of persistent hypertension.The cardiovascular prognosis is even more guarded in diabetics with more cardiovascular and renal complications, especially when the hypertension is nocturnal.