Hypertension Basics - Hypertension in Diabetics

Author:

New York Presbyterian Hospital - Columbia Presbyterian Medical Center

Medically Reviewed On: March 31, 2006

The number of people with diabetes (high blood sugar) in the U.S. continues to increase due to our aging population, sedentary lifestyle, and the number of overweight (obese) people. Hypertension (high blood pressure) is twice as common in people with diabetes than in people without diabetes. There are two types of diabetes: the classic insulin-dependent form, or type 1 (often diagnosed at a young age and makes up about ten percent of all diabetics), and the insulin-independent form, or type 2 (usually presents around middle age and accounts for 90 percent of all diabetics.)

In the two types of diabetes, obesity is present in most of the people with type 2. Hypertension is also more common in people with type 2 diabetes. On the other hand, kidney malfunction (nephropathy) is very common in type 1 diabetics—present in about 40 percent. In general, diabetics have increased risks of stroke, heart attack, heart failure, and peripheral vascular disease than non-diabetics. These risks are increased further in the presence of hypertension.

How Does Diabetes Cause Hypertension?
Although we don't know all the reasons why hypertension is very common in diabetics, the little that we do know allows the belief that it is the increase in blood insulin in both types of diabetes that promotes hypertension by affecting key checkpoints in the body. For example, increased blood insulin makes the blood vessels widen (vasodilate) and this widening of the blood vessels affects the sympathetic nervous system that increases blood pressure (BP), directly or indirectly, by making the kidney retain salt. Another way the increase in blood insulin can lead to increased blood pressure is by promoting atherosclerosis, which hardens the blood vessels.

It is also believed that those diabetics (especially type 2) who live with untreated high blood sugar for a long time are more likely to have hypertension due to early atherosclerosis.

What Blood Pressure is Considered Abnormal if I am Diabetic?
For my patients with type 2 diabetes and/or family history of both diabetes and hypertension, I encourage them to have their blood pressures followed very closely. Usually, if the blood pressure remains equal or greater than 140/90 over two or more weeks of several measurements, the diagnosis of hypertension is made. However, the diagnosis of hypertension has to be entertained and probably be made if you are diabetic and have blood pressure in the borderline range of 130-139/85-89 mm Hg.