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Thursday, March 23, 2006

Diabetes and the heart disease

ALMOST 15-20 % of our population, including those in the rural areas of Malaysia, suffer from diabetes mellitus. And approximately 30-40% of our heart patients have diabetes as well.

Diabetics do worse in all measures of heart disease outcomes, be it angioplasty outcomes, bypass surgery outcomes, heart attacks outcomes and even plain angina attack outcomes. That is why cardiologists spend a lot of their time understanding diabetes. We have discussed coronary artery disease (CAD) in detail through our previous 11 articles over the last six months. Today we will try and understand how diabetes is the bad-tempered close relative of CAD.

Diabetes mellitus

Diabetes is “kenching manis”, or sweet urine, giving us our first impression that diabetes is a condition of too much sugar in the urine. There is too much sugar in the blood, causing the excess sugar to overflow into the urine.

Well this impression is largely correct. But the reverse must also quickly be mentioned, so as to correct a very large and present misconception, and that is, if there is no sugar in the urine, I do not have diabetes. Well this is not true. Back in the 60s and early 70s, we used to use urine sugar as a way of testing for diabetes. You remember the Benedict’s solution as a way of testing for sugar in the urine? This has been found to be unreliable and largely abandoned, although being a cheap test, some clinics continue to use it as a rough guide to diabetes follow-up.

Sugar is a simple molecule, circulating freely in the blood circulation, reaching all organs, and helping all cells to function. It is the energy-providing, life-sustaining molecule that all cells require.

Diabetes occurs when there is too much sugar in the blood stream and yet this high blood sugar level somehow cannot get into the cells where it is required. As we often say, it is almost like the saying “water, water everywhere, but not a drop to drink”.

Now to the science of diabetes through the eyes of a cardiologist – the pancreas is a leaf-shaped organ situated at the back of the abdomen, lying stretched across the spine. This organ is mainly responsible for the regulation and maintenance of blood sugar levels within a narrow range of about 4-6 mmols/litre.

Too low a level will make the cells malfunction, just as would too high a blood sugar level. Depending on which cells or organs are affected most, hypoglycaemia (low sugar level) it may present as lethargy and tiredness on the one hand, or violence and aggression on the other.

Of course, extreme hypoglycaemia can result in coma. Hypoglycaemia is a much lesser medical issue then hyperglycaemia (high blood sugar), and is usually the result of drug treatment for hyperglycaemia.

The pancreas produces insulin, a hormone that is required for the proper maintenance of blood sugar levels. It basically facilitates the movement of sugar from the blood stream into cells and tissues for their energy-requiring functions. Sugar in the cells is broken down to produce energy to drive the cell’s function.

Insulin production is increased in response to high circulating blood sugar level, as will occur after meals containing carbohydrates/sugar.

The increased outpouring of insulin after a meal causes the sugar in the blood stream to move into cells and tissues (eg muscle cells, brain cells and heart muscle cells) so that these cells can use the sugar to produce energy for their important functions.

Excess sugar is stored in the liver with the help of insulin. In the event of low sugar levels in the blood, the pancreas also produces another hormone, called glucagon, which functions to facilitate the movement of sugar out of the liver cells where sugar is stored and to the blood stream to normalise the blood sugar level. So like all body systems, there is always a “yin-yang” balancing to maintain body equilibrium.

Diabetes: the heart and blood vessels

Maintaining blood sugar levels is not what concerns a cardiologist primarily. This is the province of the endocrinologist. Cardiologists are more concerned about the effects of chronically elevated blood sugar.

When the pancreas malfunctions, there is insulin deficiency, and blood sugar rises, sometimes severely. These issues are very well studied, and has been addressed with the use of insulin injections (discovered by Dr F. Banting and Charles Best in 1921) and also the drugs that work primarily in stimulating the pancreas to produce extra insulin, like glibenclamide.

In the 21st century, we have obesity by the ton, forgive my pun. Obese people can have high levels of insulin and yet high levels of blood sugar. This paradox was initially puzzling but we now know that the potbelly produces substances that cause the body cells not to respond to insulin. In our language, obesity causes insulin resistance.

This truncal obesity, together with hypertension, insulin resistance, high triglyceride and low HDL-cholesterol, form a syndrome that we call the “metabolic syndrome”, truncal obesity being the main component of this cardio-damaging disease.

The potbelly is a very active organ (not as docile as it may seem), producing hormones and chemicals that cause insulin resistance, diabetes and hypertension and these two in combination severely aggravate heart disease.

Persistent high insulin levels, as often occurs with insulin resistance, changes excess blood sugars into fats, and this further aggravates the potbelly.

Hence, a potbelly begets a potbelly. What’s worse, the persistent high blood sugar causes the blood, blood cells and also the artery wall cells, including the heart, kidney and brain arteries, to be sticky. This promotes blockages in the artery wall.

Therefore, although pancreatic malfunction causes one type of diabetes, obesity and potbelly, very much a 21st century disease, causes another type of diabetes, which comes with hypertension. This latter variety is highly cardiac and blood vessel damaging.

To reiterate, obesity causes insulin resistance and fat metabolism disorder, which in turn causes hypertension and diabetes mellitus (metabolic syndrome), which in turn causes coronary artery disease. When we should be sitting on our fat, we are allowing the fat belly to sit on us and cause us all these problems. Now this bothers cardiologists, a lot.

Complications of diabetes

The saying is true that no one actually dies from diabetes itself anymore. The pre-insulin days where patients waste away from severe high blood sugar and diabetic coma is nowadays a rarity with the advent of insulin. That’s why, I guess, Dr Banting and Best won the Nobel prize for Physiology in 1925.

Patients with diabetes nowadays develop kidney, eyes, brain and nerves, and heart and blood vessel complications. In fact all the diabetic complications are blood vessel related. Small blood vessel damage leads to eye problems, kidney disease, kidney failure and nerve damage. Bigger blood vessel damage leads to strokes, CAD with heart attacks and poor limb circulation resulting in amputation for some.

Eventually diabetes translates to cardiac and vascular disorders as blood vessel walls thicken and get clogged up with sluggish circulation and damaged blood vessel wall cells.

Yes, main target organs can be damaged, resulting in complications like kidney failure and renal dialysis, blindness, strokes, heart attacks, angina attacks, angioplasties, bypass surgery, limb gangrene, poor healing wounds and limb amputations.

What is also important to emphasise is that once you are afflicted with diabetes, your risk for every medical illness becomes worse. Even common cough and colds take longer to recover in diabetics, and is more likely to be complicated.

The recently reported that obese people suffer more complications following motor vehicle accidents. It is as if diabetes weakens your whole body. All cardiac procedures carry a higher risk of complications and the outcomes tend to be worse, in the short and long term, be it angioplasties, or bypass surgery.

Management of diabetes

For those who are already diabetic, please realise that your life is in your hands. Proper treatment by qualified medical practitioners can do much to delay or even avoid complications.

A careless attitude and non-compliance to medical treatment invariably results in worse outcome and target organ failure.

The drugs for the insulin deficient type of diabetes is a little different from the drugs used for the obesity, potbelly type of diabetes. There are very good drugs for both types as our understanding of the disease has improved tremendously.

We have drugs that will help the pancreas to produce more insulin, like the sulphonyl ureas, and insulin injections (for the insulin deficient kind) and drugs that sensitise the cells and tissues to insulin, like the biguanides and “glitazones” (for the insulin resistant kind).

Soon we will have a nasal spray insulin for easier administration. There is also an anti-obesity drug about to be launched that promises to make subjects lose weight and lessen the risk of heart disease, acting through a new body system called the Endocanabinoid system. Interesting. Help for the potbellies is on the way.

Prevention is better than cure

But drug treatment for diabetes, though good, is not the best strategy, both for the patient and for the nation. It is much, much better that diabetes, especially the metabolic syndrome (potbelly type), is prevented.

Potbelly is invariably the result of eating the wrong food and a sedentary lifestyle. This is the age of computers and the remote control. We want instant gratification, without ever having to move from our seat in front of the big, flat screen. We do not exercise enough. We love the elevator, even to go up one to two floors, rather than use the staircase.

Cycling to work has been suggested as a way to overcome this problem. Well, let us see how many will follow. We love junk food. Fast food, almost synonymous with junk food, is springing up all over the place. French fries are many a child’s regular diet. Add to it salt and a sugar-rich carbonated drink, you have the classical diabetic, hypertensive diet.

We have identified some of the problems. Prevention then is relatively easy, but involves sacrifice. Promoting a low salt diet (3 gms a day), with avoidance of carbonated drink would be a good start.

Fruits and vegetables are healthy and should be encouraged. White meat is preferred. Except for service lifts, and lifts for the handicapped and infirm, lifts should go to every third floor. Remote controls for TVs and radios should be banned. Regularly walk 15km a week. Have regular check-ups. All males above 40 years and all females above 50 years should go for a medical checkup.

Maintain a waistline of 34 inches (100 cm) or less, a hip to waist ratio of 0.9 and a BMI of 23-24 . Those are the targets. Need I say more? I am sure you get the message. It costs to stay healthy. As the saying goes, “Health is wealth”.

Excerpt from The Star

This article is contributed by the Federation of Private Medical Practitioners Associations Malaysia. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. We does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. We disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.

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