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The percentage rise in people diagnosed with diabetes in Dartford, Gravesham and Swanley is the third highest in the county, according to the latest health figures.
The prevalence of those identified with the condition has increased by 4.59% in the past three years.
This compares to the largest rise of 6.02% in Swale, followed by 5.34% in the South Kent Coast Clinical Commissioning Group (CCGs). Ashford has seen the lowest rise of 1.79%.
CCGs are responsible for deciding the healthcare provision and spending for its patients.
There are eight including Medway across the county, with Dartford, Gravesham and Swanley the third largest, serving 17 per cent of the registered population.
The latest figures, extracted from GP patient data, have been released by Diabetes UK and are calculated according to prevalence.
This takes into account the change in a CCG's population, regardless of whether they have been diagnosed with diabetes or not.
It represents the number of people diagnosed with diabetes in a given year, divided by the total number of people registered in a CCG for that year, and not simply the increase or decrease of diagnosed diabetes cases.
In 2012/13 there were 12,003 registered as having diabetes in Dartford, Gravesham and Swanley and this figure rose to 12,466 in 2013/14. The number now stands at 12,831.
The news comes as the number of people with diabetes in the UK has tipped over the four million mark for the first time.
Diabetes UK said the need for the NHS to provide adequate care and education was more urgent than ever.
Jill Steaton, the charity's south east regional manager, said sufferers were at the mercy of a postcode lottery and that the government should do more to tackle obesity, a major cause of Type 2 diabetes.
"Over the past three years we have continued to see the number of people with diabetes rise at an alarming rate and these latest figures are a stark call and urgent call for action to tackle this serious health condition.
"Tragically, we are continuing to see too many people with diabetes suffering serious complications, and even dying before their time, and we know that key reasons for this are that they are being denied both the care and access to education that would help them to manage their condition well."
Diabetes costs the NHS nearly £10 billion, 80% of which is spent on managing avoidable complications.
Many cases of Type 2 diabetes can be prevented, for example through weight-loss and leading a healthy lifestyle, but there is no way of preventing Type 1.
One of those who has benefited from diabetes education is Alan Eadie.
Mr Eadie, who was diagnosed with Type 2 diabetes in 2008, believes it is the fundamental part of managing his condition.
The 79-year-old, of Northdown Road, Longfield, said: "There can be no doubt education is a fundamental part of diabetes care.
"Clearly the aim of education for people with diabetes is to improve their knowledge and skills, to enable them to take control of their condition and to incorporate self-management into their everyday lives."
Once diagnosed himself, Mr Eadie wanted to find out as much as he could about the condition and has attended several courses, including DESMOND (Diabetes Education and Self-Management for On-going and Newly-diagnosed), as well as enrolling on an open university course.
However, Mr Eadie was disappointed to learn that Dartford, Gravesham and Swanley CCG does not offer the X-PERT course, structured to provide diabetes and lifestyle information and advice.
Three years after being diagnosed, he was accepted on one run by neighbouring Bexley Care Trust and said the help it provided was invaluable.
"What frightened me, and possibly some other newly-diagnosed diabetics are the potential complications that can arise as a result of one or more parts of your body becoming damaged as a result of high blood sugars.
"These complications need not be inevitable and it is possible to minimise them or even avoid altogether.
"The X-PERT course provided me with all the key information I had been searching for ever since being diagnosed. I simply cannot recommend this course too highly and I am now confident I have my diabetes well under control."
Diabetes UK is inviting people to sign up to its challenge of swimming the equivalent distance of the English Channel, but in the comfort of a pool.
Swim22 starts on February 22 and gives participants three months to complete the 22 miles.
The distance can be split between friends, teams, family or workmates. Money raised through sponsorship will help to fund diabetes research and support campaigns.
Sign up at www.diabetes.org.uk/swim22 or calling 0345 123 2399. For general information go to www.diabetes.org.uk/taking-control