Blood pressure and blood glucose variability, the silent killers, in subjects with diabetes mellitus, flying blue. A tribute to Dr. Franz Halberg on the anniversary of his death (June 9, 2013)

Limitations of the usual assessment of blood pressure, the importance of blood pressure variability, and diagnoses of unstable and episodic hypertension were described by several investigators, but much earlier by Halberg’s group in Minnesota. The International College of Cardiology reiterates that treatment decisions for patients should be dictated by their overall level of risk including blood pressure variability. Halberg et al. have demonstrated that blood pressure varies predictably along the scales of a day (circadian), a week (circaseptan), a month (circatrigintan), a year (circannual) and even along much longer periods, and that blood pressure variability (BPV) is associated with cardiovascular health. BPV reflects both an individual’s genetic makeup and a wide range of influences from the near and far environment, including behavior, diet and other lifestyle choices. Mechanisms underlying the coordination of a broad time structure characterizing blood pressure are not completely understood, even though humoral, neural, and central or reflex influences have been documented. An elevated blood pressure complicated by altered BPV may be a substantial contributor to overall morbidity and mortality, and may particularly affect patients with diabetes. Ambulatory blood pressure monitoring (ABPM) interpreted chronobiologically may help in the diagnosis of autonomic neuropathy resulting in adverse effects on autonomic control of the cardiovascular system. These autonomic dysfunctions may be associated with an odd timing of the circadian rhythm in blood pressure and with reduced 24-hour heart rate variability. A large body of evidence supports the increase in cardiovascular disease risk in association not only with elevated blood pressure values but also with altered BPV.