In Barking and Dagenham there are 3,800 people at risk of losing their sight as a result of having diabetes, according to research by the Royal Institute of Blind People.
Of those, 350 people with severe diabetic retinopathy are likely to suffer significant sight loss.
It is estimated there are 10,420 diabetics in the borough.
As part of Diabetes Week, which runs June 11 to June 17, Olympic rower Sir Steve Redgrave, who has type 2 diabetes, is working with opticians Specsavers to warn people of the risks of going blind.
He said: “Since being diagnosed with type 2 diabetes, I have learnt how important it is to get regular eye checks to detect signs due to complications.
“Yet with early detection through regular eye tests and specialist diabetic eye screening followed by timely treatment, sight loss due to diabetic retinopathy can be prevented.”
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