Self-monitoring of blood pressure

Many people with diabetes also suffer from high blood pressure. In type 2 diabetes, hypertension is part of the metabolic syndrome and is twice as common as in people without diabetes.

In contrast, in people with type 1 diabetes, hypertension is often a sign of nephropathy. Proper blood pressure control is closely linked to the development of diabetic complications, which is why close monitoring of blood pressure is important.

Diabetes and hypertension share the characteristic that elevated values often go unnoticed. The typical patient with hypertension has become accustomed to their high blood pressure levels and often becomes aware of the disease only when complications such as stroke or heart attack occur. The connection between blood pressure control and complications was demonstrated, among others, in the historic British UKPDS study, which observed more than five thousand people with type 2 diabetes [1]. The study showed a reduction in the risk

– of stroke: by 44%
– of diabetic complications affecting the eyes and kidneys: by 37%
– of death attributable to diabetic complications: by 24%,

when blood pressure was lowered by just 10 mmHg (the patients had an average blood pressure of 154/87 mmHg before the intervention and 144/87 mmHg after the reduction).

Once a diagnosis of hypertension has been made, self-monitoring of blood pressure is an important component of therapy. It is well known that blood pressure values measured in a doctor’s office are often not representative. Blood pressure also varies with physical exertion, emotional stress, and changes in the weather. To obtain reliable readings, blood pressure should be measured daily over several days.

Points to consider when performing blood pressure self-monitoring:

  • Blood pressure should be measured regularly at fixed times and always on the same arm, if possible. The ideal time is directly in the morning before breakfast, as high morning blood pressure is considered particularly dangerous.
    • Before measuring, the person should sit and relax for a few minutes to achieve physical and emotional calm.
    • Devices with upper-arm cuffs are preferable to wrist-cuff devices. Patients with diabetes frequently have medial arterial calcification (Mediasklerose). Mediasklerosis (also known as Mönckeberg’s sclerosis or medial arterial calcification) is a form of arterial calcification in which the middle layer (media) of medium-sized arteries becomes calcified. It differs significantly from the widespread atherosclerosis, which affects the inner layer (intima) and leads to plaque formation. Calcium deposits accumulate in the media without narrowing the inner vessel lumen.
    The arteries become stiff and lose their elasticity, but blood flow is usually maintained because the lumen (the passage through which blood flows) is not narrowed. In medial calcification, arteries are hard and barely compressible—more like a “pipe” than an elastic vessel. The cuff cannot completely compress the artery.
    The device often interprets this faulty pressure signal as a much too high systolic value or produces highly fluctuating readings.
    • The width of the cuff must match the circumference of the upper arm. For larger upper-arm circumferences, a wider cuff should be used.
    • The measuring device should be calibrated.
    • The measurement site should be at heart level during the measurement. With upper-arm cuffs this is automatically the case, whereas with wrist cuffs the wrist must be held at heart level.
    • Before performing a repeat measurement, at least 30 seconds should pass.
    • Although blood pressure values and pulse are stored in the devices, it is still useful to record them in a blood pressure diary or in an appropriate app.

Literature:

[1] Adler AI, Stratton IM, Neil HA, Yudkin JS, Matthews DR, Cull CA, Wright AD, Turner RC, Holman RR. Association of systolic blood pressure with macrovascular and microvascular complications of type 2 diabetes (UKPDS 36): prospective observational study. BMJ. 2000 Aug 12;321(7258):412-9. doi: 10.1136/bmj.321.7258.412.