Diabetic Patients With Hypertension Have A Significantly Higher Risk For Cvd Than Nondiabetic Patients

Hypertension increases CV risk in type 2 diabetes mellitus (T2DM) enormously, as clearly demonstrated in the Multiple Risk Factors Intervention Trial, in which 350,000 men between 35 and 57 years of age were followed up for twelve years (3). The absolute risk of CV death was three-fold higher in those who were diabetic, even after adjusting for other common risk factors such as age, race, income, serum cholesterol and smoking. Importantly, the risk at any given level of systolic blood pressure (SBP) was 2.5-3 times higher in those with T2DM than in the non-diabetic patients at every level of SBP assessed (3). Hypertension is also thought to play a major etiologic role in the development of diabetic nephropathy (DN) and diabetic retinopathy (4,5). As a result, many experts and authors have argued that blood-pressure (BP) management is the most critical aspect of the care of patients with T2DM.

Recently, findings from the Strong Heart Study (6) demonstrated that the high risk for CVD associated with BP levels in diabetic patients starts already in the phase of pre-hypertension (Pre-HT) [SBP: 120-139 mm Hg and/or diastolic blood pressure (DBP) of 80-89 mm Hg]. Pre-HT was more prevalent in the diabetic versus nondiabetic patients (59.4% vs. 48.2%; p= 0.001). After a follow-up period of twelve years the hazard ratios (HR) of CVD were 3.70 for those with both Pre-HT and diabetes, 2.90 for those with diabetes alone and only 1.80 for nondiabetic patients with Pre-HT. Based on these findings more aggressive interventions (drug treatment for BP control) for prehypertensive individuals with diabetes seem to be warranted.

ABNORMAL DIURNAL VARIATION OF BLOOD PRESSSURE (NONDIPPING)

The mechanism that underpins the increased sensitivity of diabetic subjects to hypertension is not known, but may involve impaired autoregulation or attenuated nocturnal decrease of BP. There is a growing evidence that a decreased nocturnal fall in BP (< 10% of the daytime level) is associated with a worse prognosis, irrespective of whether nighttime dipping is studied as a continuous or a class variable. Various studies (7-9) indicate that in diabetic patients, measurement of ambulatory 24 h BP is a much better predictor of microvascular and macrovascular complications than conventional BP measurement. An abnormal circadian variation of BP ("nondipping") can be demonstrated in a considerable number of diabetic patients and was found to be related to microalbuminuria and DN (7-9). Nondipping was also found to be associated with glucose intolerance, insulin resistance and enhanced nocturnal sympathetic activity even in nondiabetic patients (10). A disturbed diurnal variation of blood pressure is a predicting marker for progression of both diabetic retinopathy and DN in type 1 diabetes mellitus (T1DM) patients (7-9). A 20-fold risk of dying within the next 5 years was found in those T2DM patients, who had a "reversed" circadian BP profile compared with patients who had a normal decrease in BP during nighttime (11). Interestingly, most sudden deaths or strokes in that study occurred during nighttime or early morning (11). More research is needed to clarify whether the increased risk for end-organ damage can be lowered in diabetic patients with abnormal circadian variation of BP by specific intervention strategies (12).

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