If your doctor has told you that you have high blood pressure, or hypertension, you may well have groaned at the thought of more dietary restrictions and/or another pill to take. Or maybe you just tuned him out. After all, you have enough to do with caring for your diabetes, and how serious could high blood pressure be, anyway, since it has no symptoms?
In fact, high blood pressure is very serious. But paying attention to it now can save you a lot of grief down the road.
Why it matters
High blood pressure is one of the most important risk factors for stroke, heart attack, and kidney failure in people with diabetes. While the relationship between high blood pressure and diabetes is not fully understood, it is known that high blood pressure is two times more common in people with diabetes than in the general population. More than half of people with Type 2 diabetes already have high blood pressure at the time of their diabetes diagnosis.
In a person with diabetes, high blood pressure accelerates the blood vessel damage caused by high blood glucose. High blood pressure contributes to more than two-thirds of the serious and life-threatening complications of diabetes, including stroke, heart attack, and kidney failure. However, numerous studies have shown that treating high blood pressure aggressively substantially reduces the risk of death from stroke and heart attack.
For people with diabetes, the goal for blood pressure control is to keep it below 130/80 mm Hg. This target was established on the basis of large-scale studies that showed significant reductions in stroke and heart disease when blood pressure was maintained at this level. However, studies also suggest that blood pressure goals are not being met: Only about a third of people with diabetes are reaching this goal consistently.
Understanding blood pressure
The heart pumps blood through more than 93 miles of blood vessels, which act as a plumbing system, carrying blood to all the vital organs. A certain amount of pressure within this system is necessary to keep the blood moving, but too much pressure can damage the vessels and organs. If the heart pumps too hard or the body’s smaller blood vessels become narrow, the pressure rises. If a person’s blood pressure is persistently elevated, the diagnosis of high blood pressure is made.
Blood pressure is measured in millimeters of mercury (mm Hg). The first, or “top,” number is the systolic pressure and measures the force on the blood vessel walls as the heart squeezes, or contracts. The second, or “lower,” number is the diastolic pressure, which is the force on the vessel walls as the heart relaxes. A person’s blood pressure is categorized as normal, prehypertensive (high-normal), or hypertensive. The hypertensive group is further divided into stage 1 and stage 2, based on how high the measurements are above normal. Stage 1 refers to blood pressure levels from 140/90 mm Hg to 159/99 mm Hg. Stage 2 refers to blood pressure levels of 160/100 mm Hg or higher.
Blood pressure is very dynamic, meaning that it can change instantaneously in response to the internal or external environment. For example, if you have an injury that causes severe bleeding, your blood pressure drops rapidly. But your body also responds to that drop within seconds by squeezing and narrowing the blood vessels and increasing heart activity to bring the pressure back up.
The body has numerous ways of adjusting blood pressure as needed to be sure its organs (primarily the brain) maintain a good supply of oxygen. This dynamic response is part of the reason some people have what is called white-coat hypertension. Being nervous in the medical office can result in a substantial increase in blood pressure that is not present at home. White-coat hypertension can make it difficult to get an accurate blood pressure measurement.