Diabetes is a long-term condition that causes a person's blood sugar level to become too high. Type 1 and Type 2 diabetes are the two types of diabetes, with the latter being the most common in the UK.
Of the 3.9 million people with diabetes in the UK, 90% of adults have type 2 diabetes.
It is estimated that 5 million people will have diabetes in the UK by 2025.
The amount of sugar in the blood is controlled by the insulin hormone, produced by the pancreas (a gland behind the stomach).
When food is digested and enters your bloodstream, insulin moves glucose out of the blood and into cells, where it's broken down to produce energy.
If you have diabetes, your body cannot breakdown glucose into energy, because there's either not enough insulin to move the glucose, or the insulin produced doesn't work properly.
If you have diabetes, your eyes are at risk from diabetic retinopathy, a condition that can lead to sight loss if it's not treated.
Screening, which involves a half-hour check to examine the back of the eyes, is a way of detecting the condition early so it can be treated more effectively.
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