Over 2 million Canadians have diabetes. It is the leading cause of
blindness in North Americans under 65 years of age. Diabetes is a condition
where the body either cannot produce enough insulin (胰岛素) or cannot respond
properly to insulin. Insulin is important because it moves glucose (葡萄糖), a
simple sugar, into the body's cells from the blood. The food people eat provides
the body with glucose, which is used by the cells as a source of energy. If
insulin isn't available or doesn't work correctly to move glucose from the blood
into the cells, glucose will stay in the blood, leading to high blood sugar
levels. High blood sugar levels damage the blood vessels,
including the tiny blood vessels in the eye. This leads to an eye disease known
as diabetic retinopathy (糖尿病型视网膜病). The retina (视网膜) is an area at the back of
the eye that changes light into nerve signals. With diabetic retinopathy, some
blood vessels in the retina are lost, and some of the other blood vessels begin
to "leak" blood. This causes the retina to swell, and gradually cuts off its
supply of oxygen and nutrients (滋养物). Eventually, the retina starts to grow new
blood vessels to replace the damaged ones. Unfortunately, these new vessels are
not as strong as the old ones. They are more likely to break, Causing bleeding
in the eye. At first, people with diabetic retinopathy will not
notice any symptoms. As the disease gets worse, they may notice blurred (模糊的)
vision, black spots or flashing lights. As time goes on, it can progress to
blindness. Everyone with diabetes is at risk for diabetic retinopathy, and the
risk increases the longer you've had diabetes. Fortunately, you
can reduce your risk. If you do not have diabetes, but think you may be at risk
for this condition, visit your doctor to be screened for diabetes. If you do
have diabetes: have frequent eye check-ups. Make sure that you
monitor your blood sugar frequently and use your medications as recommended by
your doctor. There is evidence to show that keeping your blood sugar under tight
control can slow down eye damage. If you have high blood
pressure, follow your recommended diet and medications to keep it under control.
If you are not sure whether you have high blood pressure, or whether your blood
pressure is under control, discuss this with your doctor.
单选题
Glucose cannot be turned into energy in the body ______.