Both diabetes mellitus and arterial hypertension are commonly observed in a single patient. However, the relationship between these two entities is rather complex and there is a great heterogeneity regarding the underlying pathophysiological mechanisms and the clinical presentations. These particularities may have important consequences from a therapeutic point of view, as far as blood pressure targets or even pharmacological strategies are concerned. The present article will discuss the various causes of hypertension in the different types of diabetes, the different forms of hypertension in the diabetic patient, the modalities of treating hypertension in presence of various specific complications (metabolic syndrome, coronary heart disease or renal impairment), and the specificities when hypertension is associated with diabetic cardiovascular autonomic neuropathy.