Diabetes Forecast

Tension Mounts: High Blood Pressure

The lowdown on high blood pressure

By Erika Gebel, PhD ,

Rolling up your sleeve, hearing the sticky sound of Velcro ripping apart, feeling the big squeeze on your upper arm: Getting your blood pressure taken is a routine part of a trip to the doc's. But when your doctor or nurse reads out the numbers over the hiss of the cuff's deflation, do you know what they mean for your health? You should. More than 70 percent of people with diabetes have high blood pressure (also known as hypertension), take medication to keep it in check, or both. It's a serious health concern, and understanding the basics can keep the pressure from getting to you.

With every beat of your heart, blood surges through the winding passageways that make up your circulatory system. As blood pushes against vessel walls, the walls push back—a shoving match called blood pressure. Even if you feel fine, your blood pressure may still be high. The only way to find out is to get it checked regularly.

Numbers to Know

Blood pressure is recorded as two numbers, the systolic and diastolic pressures. You'll hear your blood pressure is, say, "120 over 70" or see it written as "120/70 mm Hg." The top line is the systolic pressure; the bottom, the diastolic. The abbreviations "mm Hg" stand for "millimeters of mercury," because blood pressure readings have traditionally been taken by a device that uses the height of a column of mercury to assess blood pressure. The systolic pressure is higher because it is measured during a heartbeat, when the heart contracts and the pressure is at its greatest. When the heart relaxes between beats, the pressure drops and the diastolic pressure is recorded.

The American Diabetes Association (ADA) defines hypertension for people with diabetes as either a systolic blood pressure of 130 mm Hg or higher or a diastolic blood pressure of 80 mm Hg or more, on two consecutive doctor visits. A second reading is necessary because one's blood pressure tends to fluctuate depending on exercise, sleep, time of day, and emotional state. Sometimes, home monitoring may be recommended if a doctor suspects that the "white coat effect," a measurable increase in blood pressure in the presence of a physician, is causing high readings.

Your Target

For people with diabetes, the American Diabetes Association recommends that blood pressure be below 130 mm Hg/80 mm Hg

Mercury Rising

Circulation is complex, and so are the causes of high blood pressure. One contributing factor is blood volume. Blood pressure rises as blood volume increases, as if your blood vessels were a water balloon being filled. This is why a salty diet may result in high blood pressure: Sodium doesn't travel in blood alone; it needs to be hydrated. As water floods into the blood to join the sodium, blood volume increases, causing pressure to rise. (There's no doubt that sodium affects blood pressure, but there is conflicting research about just how much impact salt in the diet has on it.)

Another way blood pressure rises is through the narrowing of blood vessels. Just as it's easier to drink through a big straw than a little one, blood flows more easily through larger arteries. Atherosclerosis (fat buildup on blood vessel walls), a risk factor for heart attacks and strokes, can narrow, harden, and clog blood vessels, increasing blood pressure.

Doing Damage

High blood pressure takes a toll in part because it forces the heart to struggle to keep blood flowing through your arteries. This stress can enlarge and weaken the heart. Also, as blood is forced through your blood vessels, it can damage their inner walls and lead to atheromas. These clumps of cell debris and fat can narrow the blood vessels; their accumulation is a part of atherosclerosis, which in turn causes higher blood pressure, in what can become a vicious cycle.

The eyes and kidneys are also vulnerable to high blood pressure. These sensitive organs are laced with intricate networks of blood vessels. High blood pressure can damage the delicate vessels, causing hypertensive retinopathy (eye disease) or hypertensive nephropathy (kidney disease). Kidney damage can start its own vicious cycle; as the kidneys become less adept at removing sodium and waste from the blood, the volume of blood grows, heightening pressure. In a person with diabetes, all of this adds to the extra risk that the disease already poses for the eyes and kidneys. Even if your blood glucose control is good, an eye exam or a urine test may reveal signs that high blood pressure is damaging your eyes or kidneys, respectively.

Fighting Back

In people with mild hypertension (systolic pressure of 130 to 139 mm Hg, diastolic of 80 to 89), ADA recommends starting with diet, exercise, and other changes to bring the pressure down. Studies have shown that cutting down on salt, losing excess weight, reducing alcohol consumption, getting more exercise, and eating more fruits, vegetables, and low-fat dairy products may help get blood pressure in line. Some research suggests that having low potassium may increase blood pressure, but talk with your doctor before taking a supplement: Too much potassium may be harmful for seniors and those with kidney disease. A healthy, well-balanced diet should provide all the potassium you need. In people with more severe hypertension or when blood pressure remains high after three months of lifestyle changes, your doctor may decide that medication is necessary.

There are numerous blood pressure medications, many of which are also used for other conditions, such as heart failure, angina, and arrythmia. Many people, especially those with diabetes, require multiple medications to reach their blood pressure targets.

Because these medications lower blood pressure, their side effects may include drowsiness, light-headedness, and erectile dysfunction. Special care must be taken during pregnancy, so be sure to let your doctor know if you are or plan to become pregnant. Here is a rundown of common blood pressure–lowering medications; many of them are also available as combinations, with two types of medication in a single pill.

  •  Alpha blockers dilate blood vessels to reduce blood pressure. They work by keeping the hormone norepinephrine from flexing the muscles in blood vessel walls.
  •  Angiotensin-converting enzyme (ACE) inhibitors increase the size of blood vessels, giving blood more wiggle room and thereby lowering blood pressure. A common side effect of ACE inhibitors is developing a cough. ACE inhibitors have a bonus function for people with diabetes because they can help protect against kidney damage (nephropathy).
  •  Angiotensin receptor blockers (ARBs) work similarly to ACE inhibitors, increasing blood vessel capacity. ARBs also can protect against nephropathy in people with diabetes.
  •  Beta blockers make the heart beat slower and with less intensity, decreasing the force of blood as it enters the arteries.
  •  Calcium channel blockers alter calcium mobility in the heart and vessels, which affects how hard the heart pumps. This medicine can both relax the heart and dilate the arteries to reduce blood pressure.
  •  Diuretics, such as thiazides, are the oldest and most well-studied blood pressure–lowering medications. They work by getting the kidneys to rid the body of excess fluids and sodium through urination, reducing blood volume and pressure. It is important to monitor potassium levels, though.

Taking multiple meds can be a headache, and cutting salt out of your diet may seem like tough going. But figuring out a way to keep your blood pressure down—for the sake of your eyes, kidneys, and heart—is just too important to ignore. A healthy blood pressure is something you and your doctor can achieve. So maybe it's time to put a little gentle pressure on yourself and get started.



Take the Type 2
Diabetes Risk Test