Friday, April 07, 2006

Diabetes and Heart disease

Diabetes mellitus runs at around 15-20 % of our population, even in rural areas of Malaysia. Heart patients have it even worse with the figures running about 30-40%. 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 cardiologist spend a lot of their time understanding diabetes. After extensively discussing coronary artery disease (CAD) in great detail we will try and understand how diabetes is the bad-tempered close relative of CAD.

The Chinese people in ancient times identified diabetes as, literally, "Sweet urine". The Malay term "kencing manis" is also a direct translation. This gives us a first impression that diabetes is a condition of too much sugar in the urine. The logic is simple. There is too much sugar in the blood, causing the excess sugar to overflow into the urine. This impression is largely correct. But the reverse must also be mentioned, so as to correct a very large and present misconception, that is, if there is no sugar in the urine, I do not have diabetes. This is not true.

Back in the sixties and early seventies, we used to test urine sugar for diabetes. You remember the "Benedict’s solution" test for sugar in the urine? This has been found to be unreliable and largely abandoned although it is a cheap test, and some way out clinics continue to use it as a rough guide to diabetes follow-up. Well I suppose it is better then nothing.

Sugar is a simple molecule, circulating freely in the blood, reaching all organs, and helping all cells to function. It is the energy providing, life sustaining molecule that all cells require. Diabetes is when there is too much sugar in the blood stream and yet this sugar, despite the high blood level, somehow cannot get into the cells where it is required. It is almost like the saying “water, water everywhere, but not a drop to drink.

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

Too low a level will make cells malfunction, just as would too high a blood sugar level. Depending on which cells or organs are affected most, hypoglycemia (too low sugar level) may present as lethargy and tired on the one hand, or violence and aggression on the other. Of course, extreme hypoglycemia can result in coma. Hypoglycemia is a much lesser medical issue (high profile criminal cases excluded) then hyperglycemia (high blood sugar), and is usually the result of drug treatment for hyperglycemia.

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 tissue. Sugar in the cells is broken down to produce energy so important to drive the cell’s function. Insulin production is increased in response to high circulating blood sugar levels, which occurs after meals containing carbohydrates/sugar. The increase out-pouring 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. 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 glucagons, whose function is to facilitate the movement of sugar out of the liver cells where sugar is stored, to the blood stream, to normalize the blood sugar. So like all body systems, there is always a balancing act, to maintain body equilibrium.

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

When the pancreas malfunction,there is insulin deficiency, and blood sugar rises. That used to be problem before the 21st century. Insulin deficiency causes elevated blood sugar and it’s long term ill effects. These was very well studied and the issue was well 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 and the like.

In the 21st century, we have obesity by the ton. Obese people can have high levels of insulin and yet have 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.

The potbelly is a very active organ (not as docile as it may seem), producing hormones and chemicals that causes insulin resistance, diabetes and hypertension. These two in combination severely aggravates heart disease. Persistent high insulin levels, as often occur with insulin resistance, changes excess blood sugars into fats, and this further aggravates the potbelly. Potbelly begats 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 the 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. In summary and to reiterate, obesity causes insulin resistance and fat metabolism disorder, which in turn causes hypertension and diabetes mellitus, 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 us cardiologist, a lot.

4 comments:

tonyclide said...
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diabetes diet pre1 said...
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vicoprofen said...
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