DEAR MAYO CLINIC: What is the relationship between type 2 diabetes and high blood pressure? Does type 2 diabetes usually lead to high blood pressure? Can high blood pressure cause diabetes?

ANSWER: Many people who have type 2 diabetes also have high blood pressure. Type 2 diabetes dramatically increases a person's risk for developing cardiovascular problems, including high blood pressure. But high blood pressure doesn't cause diabetes. If you have type 2 diabetes, however, controlling your high blood pressure is very important, because high blood pressure can significantly increase your risk of serious diabetes complications.

Type 2 diabetes develops when the body becomes resistant to insulin or when the pancreas stops producing enough insulin. Exactly why this happens is unknown, although excess weight and inactivity seem to be important factors.

Insulin is a hormone that comes from the pancreas, a gland located just behind the stomach. When you eat, the pancreas secretes insulin into your bloodstream. As insulin circulates in the blood, it allows sugar to enter the cells. Insulin reduces the amount of sugar in the bloodstream. In type 2 diabetes, this process doesn't work the way it should. So instead of moving into the cells, sugar levels build up in the blood.

The buildup of sugar in the bloodstream caused by type 2 diabetes may be associated with a wide variety of complications; one of the most common is high blood pressure. Some studies have shown that as many as 60 percent of people with type 2 diabetes also have high blood pressure.

A blood pressure reading, given in millimeters of mercury (mm Hg), has two numbers. The first, or upper, number measures the pressure in the arteries when the heart beats (systolic pressure). The second, or lower, number measures the pressure in the arteries between beats (diastolic pressure). For people who have diabetes, 130/80 mm Hg or lower is a considered healthy blood pressure.

Although high blood pressure doesn't cause type 2 diabetes, it can contribute to the development of additional diabetes complications. Research has shown that diabetics with high blood pressure have a substantially greater risk of developing stroke, coronary artery disease, kidney damage, eye problems and nerve damage than people with diabetes who have normal blood pressure.

Fortunately, when the blood pressure of a patient with diabetes is controlled, so is the risk for these serious diabetes-related problems. High blood pressure can usually be controlled with a combination of lifestyle changes and medications. Making dietary changes -- especially decreasing the amount of sodium you eat -- exercising regularly, quitting smoking and losing weight can all go a long way toward controlling blood pressure.

But most people who have diabetes need medications in addition to lifestyle changes. Common blood pressure medications include angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), diuretics and beta blockers. Patients with diabetes commonly can require two or three of these medications to effectively control their blood pressure.

If you have diabetes and high blood pressure, talk to your doctor about steps you can take to bring down your blood pressure, and see your doctor regularly for checkups. High blood pressure rarely causes symptoms, so it's important for people with diabetes to have their blood pressure checked at every appointment to ensure it remains at a healthy level.

-- Yogish Kudva, MBBS, Endocrinology, Mayo Clinic, Rochester, Minn.

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