Dr. Joseph D McCracken, MD

To understand blood clots, you have to understand platelets, or blood cells that look like rumpled sheets from an unmade bed.

Platelets form blood clots when they land on top of irritated, inflamed plaque. Although the platelets are trying to ease the inflammation, they only cause more, which brings even more platelets. These platelets pile up until they fill the entire artery, which will cut the heart off from its blood supply.

Platelets do good work if you nick yourself with a razor. They're nice and calm until they come up against something rough. When they do hit that rough patch, they degranulate and grab on to the lining like it's a life preserver. If the roughness is a cut in the skin, you're glad they arrived on the scene because they're there to make a clot at the end of the blood vessel, which helps you stop bleeding.

But if that rough patch is on the inside of an artery that's been plastered over with cholesterol, then these platelets can pile up until they fill the entire artery. That can cut the heart off from its blood supply. When that happens, you're in a world of trouble.

Why? Blood clots are like party guests. Sometimes they mingle; sometimes they plant in one place and block all the other guests who are trying to get into the kitchen. Sometimes a clot that's been at one party may wander down your arteries looking for a more happening scene. Like stealing your father's car, it's a thrill-seeking romp that could prove deadly. That clot may catch up to another group of party guests in an even smaller space and get completely stuck so your blood can't even get through the door. If those guests are partying in a vital area, all the festivities can be over for good-and in a hurry. That's a heart attack.

Excess blood sugar coalesces into a syrupy mixture that coats our organs and creates glasslike shards that can cut up the blood vessels and tissues of our body. The constant wounds of these sugar surges lead to chronic inflammation, which wastes our ability to defend ourselves with false alarms. As a result, we're prone to infections and arterial damage and less able to cope with common stresses we could normally fend off—like hypertension or high cholesterol, or even cigarette smoke.

Excess blood glucose also destroys the autoregulation system that controls your blood pressure.

This means that elevated blood sugar will get you frequent-flier miles with your local doctor. Frequent urination and fatigue are symptoms but not important problems like the other effects, such as arthritis, infections, kidney failure, accelerated arterial aging (that's heart attack, strokes, memory problems, and impotence), damage to the peripheral nerves, and the development of vision problems that can cause blindness.