How Diabetics Should Avoid Serious Cardiac Events

Summarized by Robert W. Griffith, MD
February 7, 2003

Introduction

The chances of having a serious cardiovascular event, such as a heart attack (myocardial infarction, or MI), stroke, or heart failure, are as high in men with diabetes as in non-diabetic men who have already had an MI. In fact, the death rate from heart disease is twice as great in diabetics than in non-diabetics. This makes it very important for all diabetics to know their heart risk factors, and to manage them appropriately and energetically. A review of the steps to take has been published, and is summarized here.

Your lifestyle

Cutting calories and increasing your activity, to the extent that this produces a modest weight loss, can delay the onset of diabetes considerably. If necessary, your physician can help with anti-obesity medication, but diet and exercise are the really effective steps to take. Obviously, smoking and excessive alcohol consumption must be prohibited, although 1-2 drinks a day may indeed reduce the risk of diabetes as well as of death from heart disease.

High blood sugar

The glycosylated hemoglobin (HbA1c) level in the blood is the best target to aim for in controlling blood sugar levels; it represents the overall level of sugar in the blood, 'smoothed out' over several months, and is a more useful assessment of long-term diabetes control than fasting or peak blood sugar measurements. Death rates in diabetics are closely linked to their HbA1c levels, and in managing diabetes one should try for HbA1c levels as low as possible, without causing hypoglycemia (abnormally low blood sugar producing symptoms: shaky, sweaty, anxious, irritability, etc). The HbA1c goal to aim for is 7% or lower - some experts recommend 6.5%.

Raised peak blood sugar levels after meals (postprandial blood sugar) are also important. One hour after a meal sugar levels should be below 160 mg/dL (8.9 mmol/L), and 2 hours after a meal, below 140 mg/dL (7.8 mmol/L). Short-acting drugs (the meglitinide class) can be taken before meals to address just this problem.

There are many different drugs used to treat high blood sugar levels. The selection is often based on the fasting blood glucose (FBG). If the FBG is over 300 mg/dL, insulin injections are usually prescribed, unless the patient is 'insulin-resistant'. In less severe cases, the choice for an oral drug lies between one of the sulfonylureas, thiazolidinediones, alpha-glucosidase inhibitors, metformin, or meglitinides. Your physician can prescribe the one that best suits your particular case. It's important to take anti-diabetic medication correctly in order to try to reach your blood sugar goals - tight control will delay diabetic complications.

Blood lipids in diabetes

Raised triglyceride levels and decreased high-density lipoprotein cholesterol (HDL-C, the 'good' cholesterol) levels in diabetics are twice as common in diabetics than in non-diabetics, so these two lipids should receive special attention. First, a baseline lipid profile should be done after you've been following your new lifestyle (diet, exercise, etc) for 6-12 weeks. Different drugs can be prescribed, according to the particular lipid problem. For triglycerides, fibrates or niacin are used. For low HDL-C and/or raised LDL-C levels, one of the statins is recommended.

The goal for LDL-C in diabetic patients is less than 100 mg/dL (2.6 mmol/L), that for triglyceride below 150 mg/dL (1.7 mmol/L), while HDL-C should be above 40 mg/dL (1.0 mmol/L). Achieving these goals is difficult, but good blood sugar control will help, particularly with regard to the triglyceride level.

High blood pressure in diabetes

The risk of diabetics having an MI is closely linked to their blood pressures, and it's well known that fewer than 1 in 3 people with high blood pressure have it properly controlled by treatment. Even modest reduction in blood pressure has been shown to reduce the risk of diabetes-related death by 32%, that of stroke by 44%, and that of heart failure by 56%. Obviously correct control of raised blood pressure is a high priority for diabetic subjects. The goal for treatment should be a blood pressure of less than 130/80 mm Hg.

There are numerous types of drugs for treating raised blood pressure. ACE (angiotensin-converting enzyme) inhibitors, ARBs (angiotensin II receptor blockers), and beta-blockers are all suitable. Recently, a large study has shown that diuretics ('water pills') are just as good, if not better, than newer drugs in the long-term treatment of hypertension, and the results apply to both diabetic and non-diabetic patients.

Other treatments

People with diabetes often ask what else they can do to ward off cardiovascular complications. A daily aspirin, or a similar type of antiplatelet drug (clopidogrel), can help prevent clotting in small blood vessels.

There's no evidence that antioxidants or vitamin supplements are particularly valuable in diabetic patients. Adequate folic acid - usually achieved by eating plenty of green vegetables, or taking a supplement - will counter any high levels of blood homocysteine, which is sometimes seen in diabetic, as well as non-diabetic, subjects.

Diabetics tend to have higher blood C-reactive protein (CRP) levels than non-diabetics, suggesting an increased role of inflammation in the accelerated atherosclerosis seen in diabetes. Statin drugs have been shown to lower CRP levels, an effect that is independent from their LDL-C lowering action.

Comment

While diabetes is increasing worldwide, so is our ability to combat many of it's effects. Apart from major changes in lifestyle (weight control, exercise, not smoking), tight control of blood pressure is probably the most important measure to reduce deaths and heart disease. Better control of blood glucose, blood pressure, and lipid levels should ensure that one reduces the long-term effects of this disease. Don't leave it too late!

Source

• Cardiovascular disease in type 2 diabetes mellitus. Current management guidelines. AD. Mooradian, Arch Intern med, 2003, vol. 163, pp. 33--40

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