Diabetes mellitus and obesity are both related to the risk of cardiovascular disease and sudden death. In hypertensive guidelines, diabetes and obesity, especially abdominal obesity, are regarded as high-risk factors. Ambulatory blood pressure monitoring (ABPM) is an established method for the management of hypertension. However, ABPM is not a standard tool for the management of hypertension in diabetes and obesity. In this paper, recent data on the use of ABPM in diabetes and obesity will be discussed. In patients with diabetes, the ambulatory BP level has been shown to be better than clinic BP in predicting cardiovascular events. A riser pattern has been associated with increased risk of cardiovascular disease. White-coat hypertension and masked hypertension in diabetics constitute a moderate risk. A nondipping pattern is very common in obese hypertensive patients. In this paper, we will summarize the findings on the use of ABPM in patients with diabetes and obesity.