Diabetes mellitus and hypertension: The double whammy

Diabetes mellitus and hypertension are very common chronic maladies that frequently occur together. Although both diseases are common, their concurrence is significantly greater than would be predicted by chance alone. The coexistence of these chronic diseases increases the risk of and mortality from such conditions as myocardial infarction, stroke, peripheral vascular disease and nephropathy. Despite the clinical relevance of hypertension in diabetic individuals the fundamental pathophysiological mechanisms which initiate and sustain the hypertension remain poorly understood and controversial. This review addresses the epidemiology and pathophysiology of hypertension associated with diabetes mellitus. We explore the possibility that a common ionic mechanism underlying the pathogenesis and maintenance of hypertension in both type I (insulin deficient) and type II (insulin resistant) diabetes mellitus both causes and/or results from a deficiency of insulin action at the level of vascular smooth muscle (VSM) tissue. Results from recent studies suggest that impaired cellular responses to insulin contributes to increased VSM tone, the hallmark of hypertension associated with both type I and type II diabetes mellitus. In particular, abnormal insulin modulation of VSM cell cation homeostasis may result in decreased insulin mediated vasodilatation and thus in the hypertension associated with type I and type II diabetes mellitus.