Why is having excess sugar in our bloodstream dangerous?

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.