Hypertension in Diabetics

Diabetes is a disease in which the quantity of sugar (glucose) in the blood is elevated. Blood sugar is maintained at a stable level by the action of several hormones. One of these, insulin, is secreted by the pancreas. If the pancreas doesn’t produce enough insulin, the blood sugar goes up (Type 1 diabetes). If the body-produced insulin doesn’t work properly, the blood sugar also rises (Type 2 diabetes ).

Type 1 diabetes (also called Insulin Dependent Diabetes) usually starts at a young age in people below 30 years old.

Type 2 diabetes (also called Non-insulin Dependent Diabetes) usually starts later in life, after 30 years of age. People with this problem still produce insulin, sometimes excessively. However, for various reasons including obesity, their insulin is less able to decrease blood sugar. Moreover, the quantity of insulin produced can also diminish with age.

High blood pressure is nearly twice as common in people with diabetes. Blacks have more chances of having both diabetes and high blood pressure than whites, and Hispanics have three times more chances. Although Hispanics have about the same risk for high blood pressure as whites, their risk for diabetes is much higher. Once one develops diabetes, odds for developing high blood pressure also increases.

Whatever be the ethnic group to which one belongs, having both diabetes and high blood pressure is serious. Between 35 percent and 75 percent of all complications associated with diabetes can be attributed to having high blood pressure. High blood pressure also increases the chances for death from diabetes.

Treatment of Diabetes

Diabetes treatment begins with diet. For type 2 diabetics, medication that lowers blood sugar (called oval hypoglycemic agent-hypoglycemia means low blood sugar) may also be required. Insulin injections (one or more per day) are needed for all type 1 diabetics, and for some people with type 2 diabetes.

There are two main goals of treatment. The first is to prevent life-threatening high blood sugar. High levels of sugar in the blood can lead to coma (unconsciousness). Before the discovery of insulin, this was often fatal for type 1 diabetics.

The second goal is to keep blood sugar levels as normal as possible. Strict control of blood sugar prevents late complications, which can be a consequence of either types 1 or 2 diabetes.

Late Complications of Diabetes

Diabetes affects blood vessels at two levels. When large arteries are affected the complications are called Macrovasular. When the small vessels (arterioles and capillaries) are affected, the complications are Microvascular.

Macrovascular Complications

Diseased large arteries progressively obstruct blood flow to the heart (coronary arteries), brain and legs. Symptoms vary depending on the site of obstruction. They include angina and heart attack, when the coronary arteries are affected; strokes when the brain arteries are obstructed; and cramps in the legs (claudication) on exercise when the leg arteries are narrowed. Other arteries can also become clogged, including arteries to the kidneys, causing kidney (renal) failure, and to the penis, causing impotence.

Microvascular Complications

Obstruction of small vessels (also known as Microangiopathy) mainly affects the eyes and kidney. The retina, at the back of the eye, is the most affected by diabetes. Damage to the retina is called retinopathy. It is a serious complication of diabetes and causes 25 percent of all new cases of blindness, obstruction of small vessels in the kidney, effectually causes kidney (renal) failure, and to the penis, causing impotence.

Hypertension in Diabetes

Close to 50 percent of diabetics have high blood pressure too and about 15 percent hypertensive patients have problems with elevated blood sugar. The combination of hypertension and diabetes increases the chance of developing the complications. Furthermore, once complications are present, hypertension in diabetics increases the severity.

Two types of hypertension can be distinguished in diabetes:

  1. Essential hypertension
  2. Hypertension associated with renal disease (nephropathy)

Essential Hypertension in Diabetes

Essential hypertension in diabetics is probably of the same origin as in non-diabetics. Nevertheless, it has been demonstrated that diabetics have a greater tendency to retain salt and more constriction of blood vessels. Both factors will contribute to higher blood pressures.

Nephropathy

In nephropathy, the kidney doesn’t function normally, and proteins leak from the blood into the urine. Hypertension in this situation is generally attributed to the renal disease. Thus, renal disease in diabetics leads to hypertension and hypertension on its own can worsen the renal problem. This is a vicious circle with serious consequences. It can also be a warning sign of retinopathy.

Benefits of Controlling Hypertension

There are many advantages in strictly controlling hypertension in diabetics. Hypertension therapy decreases protein losses in urine and slows the rate of kidney function deterioration. In this way, the vicious circle can be broken. Good control of hypertension in diabetics also decreases the risk of stroke and the progression of retinopathy.

When Hypertensions should be treated

All diabetics with diastolic blood pressure exceeding 100 mm Hg benefit from anti-hypertensive medication. If any vascular complications, including retinopathy and nephropathy, are detected, it is preferable to treat diastolic blood pressures of 90 mm Hg or higher to slow their progression. Indeed, many doctors believe that all diabetics with diastolic pressure at or above 90 mm Hg should be treated for high blood pressure even if there are no vascular complications.

It has been known that kidney disease in diabetes starts with the leaking of certain proteins (albumin) from the bloodstream into the urine in increasing quantities. Thereafter, the kidney function declines progressively. More recent studies have focused attention on the excretion of very small quantities of Albumin Microalbuminuria). Microalbuminuria starts several years before the development of major renal problems. It can also be a warning sign of retinopathy. With special lab tests, we can recognise at an early stage who is at risk of developing these diabetic complications.

Non-drug Treatment for Hypertensive Diabetics

Lifestyle Changes

Losing excess weight and keeping a healthy lifestyle are essential. They help to decrease blood pressure and improve the control of the blood sugar. Furthermore, the abnormal lipid (fatty substances in the blood) levels common in diabetes can frequently be improved. Decreased salt intake has added benefit because salt retention is a specific problem in diabetes.

Things to avoid

Certain medications should be avoided. Non-steroidal anti­flammatory agents (such as ibuprofen, naproxen or indomethoein) can have an adverse effect of kidney function in diabetes. Corticosteroids (cortisone, predinone) can lead to hypertension and decrease the control over blood sugar. Oral decongestion in cold remedies have effects similar to non-adrenaline to which diabetics are particularly sensitive. All these medications increase both blood pressure and blood sugar.

Consumption of alcoholic beverages can also elevate blood pressure. Furthermore, excessive alcohol intake can lead to serious hypoglycaemia in diabetics treated with insulin.

Centrally acting agents and vasodilators, when other drugs are contraindicated, cause unacceptable side effects, or the blood pressure is difficult to control.

Drug Treatment for Hypertensive Diabetics

As shown in the above table several medications can be used to treat hypertension in diabetics.

ACE Inhibitors

There are medications which decrease albumin leakage in the urine of diabetics. Some of the studies have also demonstrated that they can slow the deterioration of kidney function. ACE inhibitors don’t elevate blood sugar or lipids. They can increase blood potassium and make the potassium too high, a condition known as hyperkalemia, particularly in older people, with decreased kidney and adrenal function. ACE inhibitors are an excellent choice for the treatment of hypertension for diabetics.

Calcium Antagonists

Although these medications may increase blood sugar slightly when first taken they don’t do so with long-term use. They are also an excellent choice in the treatment of high blood pressure for people with diabetes.

Alpha Blockers

These drugs don’t affect blood sugar, and furthermore, they have advantageous effects on lipids. They can worsen the tendency of some diabetics to have the blood pressure go too low on standing (orthostatic hypotension). These medications are a good choice for most diabetics, although they have a limited blood pressure lowering effect when used alone.

Arterial vasodilators

Since they increase the heart rate and cause fluid to be retained in the body when used alone, these medications are usually given with a beta blocker and a diuretic. They have no bad effects on blood sugar. They sometimes cause orthostatic hypotension.

Potassium -sparing Diuretics

These medications can be given with other diuretics to avoid the loss of potassium. Given alone, however, they may cause increased levels of blood potassium in diabetics, particularly if there is any kidney impairment. They should not be given with ACE inhibitors, which can also cause potassium to rise.

Thiazide-Type Diuretics

These medications can increase blood sugar when administered at high doses. They tend to make control more difficult in diabetics who are not taking insulin. Furthermore, thiazides in high doses can elevate cholesterol and triglycerides (major blood lipids). They may also decrease sexual function, a frequent problem among diabetics. However, these medications, particularly in low doses, are still an acceptable choice for treating hypertension in diabetics and are frequently useful in association with ACE inhibitors.

Loop Diuretics

The role of these powerful diuretics is mainly to diminish salt and water retention in diabetics with kidney or heart failure. Outside these specific situations, their effects on blood pressure are not very potent.

Beta Blockers

Beta blockers can cause problems in diabetes. First, beta blockers (mostly non-selective) decrease the symptoms produced by hypoglycaemia, which are due in great part to the effects of adrenaline. Diabetic patients with hypoglycaemia will therefore have less increase in heart rate and few or no tremors or anxious feelings, and require more time to recover from hypoglycaemia. Second, adrenaline produced during hypoglycaemia can lead to a severe increase in blood pressure if a person is taking a non­ selective beta blocker.

Finally, some beta blockers increase lipids. This effect is less with beta blockers that have intrinsic sympathomimetic activity.

Nevertheless, for those not prone to hypoglycaemia, beta blockers can be useful, especially those that are more selective, such as atenold, metoprold and acebutold.

Centrally-acting Agents

These medications do not affect either blood sugar or lipids. Thus, they can be helpful in treating high blood pressure among diabetics. However, they can aggravate orthostatic hypotension and impotence.

Conclusion

Diabetes and hypertension are common companions, and it is important to treat both well. Fortunately, there are good treatments for hypertension that don’t interfere with diabetes control. Thus it is possible to control both successfully.