A diabetic will be the first to finish the London Marathon course this weekend.

Joseph Derrett, 38, will run the 26 miles and 385 yards between Greenwich Park and St James’s Palace three times in three days, starting at 7.30am on Friday and finishing with the marathon itself on Sunday.

Joseph, of Warltersville Road, Crouch Hill, was diagnosed with type 1 diabetes after falling ill whilst on holiday in America in 2009.

Since then he has become even more determined to keep healthy, and is now hoping to raise more than £3,000 for Diabetes UK, a charity he says was invaluable in getting him used to the daily routine of insulin injections and blood sugar tests.

Joseph, who works in Parliament as a political adviser to Shadow Secretary of State for Work and Pensions, Rachel Reeves MP, said: “I’ve done marathons before, but this is different. It’s as much of a mental challenge as it is physical – you have to just not think about how far you’ve got to run.

“I did two in two days last year, which was challenging and exhausting, but well worth the effort.

Despite his condition, which requires him to have three or four insulin injections every day, Joseph has become more active since being diagnosed.

He was inspired by sporting heroes such as Sir Steve Redgrave and former Tottenham Hotspur defender Gary Mabbutt, who both have type 1 diabetes.

Joseph said: “After I was diagnosed I was reading about people who have been professional sports stars with diabetes – which shows that it’s manageable. In a funny kind of way it’s made me more determined to keep healthy.

“I ran before I got diabetes, but now I do even more and I visit the doctors more regularly.

“Raising money for the research is really important as we still don’t really know what causes type 1.”

Joseph is aiming to finish the first two efforts in under five hours each so that he has enough energy left to complete the official marathon on Sunday.

He has so far raised more than £1,500, but is hoping to have doubled that by the time he finishes his gruelling challenge.

n To sponsor him visit justgiving.com/Joe-Derrett.