Ronald Chusid, D.O.
Approximately 2.5 million Americans have both diabetes and hypertension. The presence of hypertension doubles the already elevated risk of heart disease in diabetics, as well as increasing the risk for other vascular problems such as strokes, retinal damage, and peripheral vascular disease. Hypertension also greatly accelerates the progression of kidney disease in diabetics.
Both diabetes and hypertension are particularly dangerous because they usually have no symptoms. You can be feeling fine at the same time damage to internal organs is progressing. It is important to treat diabetes and hypertension early before the damage becomes noticeable and you do feel symptoms. At an early stage these problems can be treated by following your diet, exercising, and taking medications as directed. At a later stage treatment it is often more difficult. For example, end-stage kidney disease may require dialysis, or heart disease may require bypass surgery.
The most significant study on Type 2 diabetics was jointly released in 1998. The United Kingdom Prospective Diabetes Study followed over four thousand newly-diagnosed Type 2 diabetics for twenty years to evaluate the effects of intensive treatment. The intensively treated group had fasting blood sugars reduced to 108–even tighter control than the American Diabetes Association’s goal of 120. Tight control of blood sugars resulted in a 33% reduction in kidney disease, 16% reduction in heart attacks, and a 21% reduction in diabetic retinopathy. Overweight patients on Metformin (Glucophage) showed a 39% reduction in heart attacks.
Out of this group, 1148 diabetes with hypertension were further studied to show that treatment of hypertension was critical in reducing mortality from diabetes. Their goal was a blood pressure less than 150/85. Other studies have shown further benefit in lowering the blood pressure to 130/80–and even lower when there are early signs of kidney damage. They found that it often took three or more blood pressure medications, and more frequent doctor visits, to achieve these goals. Patients who had tighter control of blood pressure showed a 44% reduction in risk of strokes, 21% decrease in heart attacks, and 37% decrease in diabetic retinopathy.
When to Treat
In order to reduce or prevent the need for dialysis in the future, changes are being made in how we treat elevated blood pressure in diabetics. While a pressure of 140/90 is a common point for treatment in non-diabetics, current recommendations are to maintain a pressure below 130/90 in diabetics. Treatment is also recommended if any signs of kidney damage are present, or if the blood pressure is elevated from the patient’s previous readings. For example, if the blood pressure has generally been 100/70 and then consistently becomes 125/80, treatment should be started. Due to the higher risk of renal disease in diabetics, many diabetologists now recommend using 120/80 as a goal for all diabetics.
The presence of kidney disease can be seen at a very early stage by performing tests on the blood and urine. A standard urinalysis will show protein in the urine. This test often misses the earliest signs of kidney damage. A urine test for microalbumin will show levels of protein in the urine which are too small to be seen in the standard urinalysis. This is the earliest sign that damage is beginning in the kidneys. The presence of microalbumin in the urine also correlates with a greater risk of heart disease. Medications should be started to protect the kidneys in diabetics if microalbuminemia is found to be present.
Choosing Medications
The presence of diabetes influences which medications are used for treatment
of hypertension. One class of blood pressure medications, ACE inhibitors (which includes
Capoten, Vasotec, Prinivil, Zestril, Monopril, and several others), are effective at
reducing the amount of microalbumin in urine and appears to be the most effective at
reducing the progression of kidney disease. These drugs can also improve sensitivity to
insulin and improve blood sugar and cholesterol levels. They also protect the heart from
changes that cause congestive heart failure, another complication of hypertension. It is
necessary to monitor blood work frequently for possible side effects of these medications.
Recent studies have also showed that some, but not, all drugs in a class called calcium channel blockers may also reduce protein in urine. Some (but not all) calcium channel blockers may also reduce microalbuminemia
Another choice is the use of Alpha blockers (Minipress, Hytrin, and Cardura). These also improve sensitivity to insulin with improvements in blood sugar and cholesterol. An additional benefit is that they reduce the size of the prostate, reducing the need for prostate surgery in men. It is necessary to increase the dosage of these medications slowly, otherwise dizziness is common. Caution must be exercised in using these medications in diabetics as they may cause postural hypotension in diabetics who are already at risk of this due to autonomic neuropathy. To reduce the risk of postural hypotension and dizziness, I recommend taking these medications at bed time.
In both diabetic and non-diabetic people with hypertension, two or more medications are commonly used in order to achieve a desired blood pressure without using high enough doses of one drug to cause side-effects. Some medications commonly used for hypertension need to be used cautiously in diabetics. Diuretics (water pills) can increase sugar and cholesterol. These side effects can be reduced by using lower doses of diuretics than were used in the past. As they are inexpensive and effective in reducing cardiac risk from heart disease, diuretics are often used first in diabetics without any evidence of kidney disease. In cases of difficult to treat hypertension requiring three or more medications, it is usually necessary to include a diuretic.
Beta-blockers can also increase blood sugar and cholesterol. These side effects can be reduced by choosing certain beta-blockers over others. Another side-effect is that they can mask some of the earliest symptoms of a hypoglycemic reaction, increasing the risk of more serious reactions. Because of these problems, beta-blockers were avoided in the past for diabetics. Beta-blockers are now used more commonly in diabetics due to their benefits in reducing the risk of heart attacks. They are generally used in people who have had a heart attack to reduce the risk of subsequent heart attacks.
As both hypertension and diabetes increase the risk of heart disease, it is necessary to control other risk factors as well as possible. This includes avoiding tobacco and controlling cholesterol to maintain the LDL portion of the cholesterol below 100.
Updated November 28, 1999
Dr. Chusid has practiced Internal Medicine in Muskegon since 1985, and has held positions including Chairman of the Department of Medicine and Chairman of the Critical Care Committee at Muskegon General Hospital. He is also an Assistant Clinical Professor of Medicine at Michigan State University, Medical Director of IHS Home Care and a member of the Council of Complications of the American Diabetes Association. His office is located at 1762 E. Oak Avenue, Muskegon, Michigan. Phone (231) 773-3258.
