By Jane Elliott
BBC News health reporter
The boat crew following Patrick Turner heaved a collective sigh of relief as the 39-year-old teacher climbed onto the French beach.
Patrick had to plan his swim very carefully
Twice on the 21 mile swim, Patrick had almost called it quits - once after four and a half hours, the second time just kilometres from his destination.
The crew, like Patrick, were determined he would succeed, but knew it was a delicate balance between helping him achieve his goal and risking his health.
For Patrick, from Watford, Hertfordshire, was no ordinary swimmer and when he reached terra firma after 14 hours and 12 minutes in the water, he became only the second diabetic to complete the swim and the first to do so on the first attempt.
His mammoth effort helped raise thousands of pounds for a local diabetic charity.
Consultant diabetic nurse Jo Butler, who monitored Patrick from the training stage and accompanied him on his swim this week, said his diabetes necessitated extra special monitoring.
"Like with other swimmers, we had to count the number of strokes he did each minute to make sure he was not becoming too tired. But we also needed to check that he was not going into a hypo (hypoglycaemic coma) .
"A couple of times he said that he was becoming too tired to continue and we had to decide whether that was because his energy stores had gone down too low. "
Patrick normally has regular glucose monitoring tests, but Jo and he quickly realised that was going to prove impossible during the swim.
During his regular training sessions they carefully monitored his glucose levels and worked out how much glucose he would need and how often he would need to take-on other drinks and food.
"We did agree though, that if he was unwell in the water that we would have to find a way to test him and to see if it was his diabetes that was causing the problem.
"But that was not necessary thankfully as the water was so choppy on the swim we would not have been able to have done it," Jo said.
"He was cold and shivering when he got back in the boat, but I did regular blood checks on the journey back and he was fine.
"It was worrying for me during the swim thinking about whether he would be alright."
Patrick needed to be carefully monitored
Patrick was already training for the swim when he was diagnosed with Type 1 diabetes last October.
Type 1 diabetes - also known as insulin-dependent or immune-mediated diabetes - is a disease that destroys the cells in the pancreas that produce the hormone insulin.
Insulin is needed to control blood sugar levels.
He started exhibiting the classic signs of diabetes - an excessive thirst, constantly dry throat, weight loss, tiredness and frequent urination.
When his doctor confirmed that he had diabetes, Patrick decided to donated part of the charity cash raised by his swim to help build a specialist resource centre for diabetes at the local Ashford and St Peter's NHS Hospital.
During training, Patrick had to change his diet so it contained a very high proportion of carbohydrates to compensate for the increase in activity - swimming in the sea can burn up to 800 calories an hour.
During the swim, he took in frequent snacks designed to boost his energy levels.
"They gave me the energy drink and hot chocolate in a sports cup which they held out on a piece of rope from the boat. I was not allowed to touch the boat.
"I also had things like tinned peaches, rice pudding and chocolate rolls from a cup, which I had to eat while treading water.
"I did get very tired and did think about getting out, but my crew persuaded me to stay in. I would not have got across without them.
"I was so exhausted when I did finish that I fell asleep soon after getting into the boat."
But despite the euphoria of finishing and of raising so much money for charity, Patrick is dubious that he will be attempting anything else as strenuous.
"I felt so bad when I got into the boat. I was vomiting sea water. I am fairly stiff, but I do feel satisfied and glad that all my training paid off.
"Would I do it again? It is too early to say, but probably not."