The estimated prevalence of type 2 diabetes mellitus (DM2) in the industrialized world is 6-8% [1
]. The prevalence of the disease is expected to increase in the coming years as a result of the increase in life expectancy in developed countries, and as a consequence of changes in life style in the developing world. It has been estimated that the number of diabetics will double over the next 25 years. As a result, by the year 2030, Spain can be expected to have over three million diabetic patients [1
]. Cardiovascular diseases are the main causes of mortality among diabetic patients [3
]. The incidence of coronary mortality in DM2 patients is four times greater than in the general population [4
]. On the other hand, the prevalence of arterial hypertension (AHT) in DM2 is practically twice as high as in the non-diabetic population. Thus, 50-60% of all DM2 patients are hypertensive, and this percentage increases with age and the presence of nephropathy [6
]. AHT in the diabetic patient is usually systolic [9
], its control poses greater difficulties [13
], and the nocturnal dip in pressure is smaller [15
]. Moreover, the concomitant presence of both conditions (AHT and DM2) increases cardiovascular morbidity-mortality - with an increased incidence of coronary, cerebrovascular, and peripheral vascular disease, renal failure, heart failure and diabetic retinopathy, and a greater risk of death due to cardiovascular disease [16
Clinical blood pressure (CBP) measurement remains the standard of reference, and has been a key element in predicting cardiovascular disease, but there is increasing evidence that home blood pressure (HBP) measurement by the patient, and particularly ambulatory blood pressure monitoring (ABPM), shows a stronger correlation to target organ damage and cardiovascular events [17
]. The prognostic value of nocturnal blood pressure (BP), and particularly of the nocturnal decrease or dip in systolic blood pressure (SBP), seems to be greater than that of diurnal BP. Individuals with a lower nocturnal fall in BP have a greater prevalence of target organ damage and a less favorable outcome [21
The presence of target organ damage increases the risk of clinical cardiovascular complications in DM2. In this context, left ventricular hypertrophy (LVH), assessed according to electrocardiographic criteria, increases the risk of coronary complications and stroke [23
]. Silent worsening of renal function, reflected by increased creatinine levels, a drop in glomerular filtration rate (GFR), or an increase in protein excretion in urine, increase the risk of cardiovascular diseases [24
]. Pathological ankle-brachial index (ABI) values show very good correlation to the development of coronary complications, the incidence of stroke, and cardiovascular mortality [26
]. In addition, a number of prospective studies have shown carotid artery intima-media thickness (IMT) to be an independent risk factor for both coronary disease and stroke [27
]. An increased IMT and/or the detection of atheroma plaques are associated with an up to four-fold increase in the relative risk of clinical complications of arteriosclerosis [28
On the other hand, the evaluation of major artery stiffness is gaining importance as an indicator, since it is one of the main determining factors of the general condition of blood circulation [29
]. Arterial stiffness is determined via two systems: pulse wave velocity (PWV)(time from arrival of the pulse wave to the carotid artery and femoral artery) and applanation radial tonometric pulse wave analysis for calculating aortic pressure, as well as the relationships between the latter and the peripheral pressure values [31
]. Increased arterial stiffness or diminished arterial distensibility determined by pulse pressure implies increased cardiovascular risk. On the other hand, there is evidence that diabetes predisposes to premature vascular aging.
Considering the need in diabetic patients to better establish the prognostic value of central arterial pressure and pulse wave velocity in relation to the evolution of the target organ damage markers (left ventricle growth indicators, renal damage markers (microalbuminuria and diminished glomerular filtration), retinal damage and vascular markers (IMT of the carotid artery and ABI)) and the possible incidence of cardiovascular events in DM2 patients, an observational prospective study involving annual follow-up over at least four years is contemplated.
The following objectives have been established
To evaluate the prognostic value of central arterial pressure and pulse wave velocity in relation to the incidence and outcome of renal (microalbuminuria, diminished glomerular filtration and the appearance of terminal renal failure), cardiac (LVH) and vascular damage (IMT and ABI), retinal vascular impairment, and the appearance of cardiovascular episodes (cardiovascular mortality, ischemic heart disease and stroke) in patients with DM2.