The majority of NHS trusts in England are not giving people with diabetes enough help in managing the condition at home, a watchdog has warned.
Weight management can reduce the risk of diabetes complications
The Healthcare Commission said most primary care trusts were offering basic diabetes care such as yearly check-ups.
But it warned that almost 130 out of more than 150 failed on home support.
Offering services to help patients manage their weight or plan an exercise regime are seen as crucial in reducing complications like heart problems.
As such, they could also save the NHS millions of pounds each year.
In 2002, about £1.3bn - or 5% of NHS expenditure - was used to care for people with diabetes.
Estimates from 2006 suggest this could even have crept up to 10% of total spending, the commission said.
Managing diabetes at home by controlling weight, or giving up smoking, have been touted as a key means of tackling complications of the condition.
As well as heart problems, these include blindness, kidney failure and limb amputation.
Beefing up community services and the potential for self-management of long-term conditions such as diabetes is also one of the key planks of government policy.
Diabetes is seen as a growing problem in the UK. According to the watchdog, the number of diagnosed and undiagnosed cases is likely to have risen by 15% between 2001 and 2010.
Some 9% of this was due to increasing numbers of obese people, and a further 6% was the result of an ageing population, it suggested.
The Healthcare Commission said England's PCTs had to do better in supporting people to manage their condition.
But chief executive Anna Walker said those that were managing to get it right deserved praise.
"They are doing more than meeting the basic needs of people with diabetes by taking that care one step further and offering the right support to people with diabetes to help them manage their condition," she said.
"This is essential to the wellbeing of people with diabetes. By managing their condition, people with diabetes can prevent serious health complications such as blindness, kidney failure and even extend their life expectancy.
"All services that provide care to people with diabetes need to look to these services and follow their example of care."
Bridget Turner, head of healthcare policy at Diabetes UK, said: "These results show that the NHS is still failing to provide the high quality care that people with diabetes need to achieve good diabetes management and stay healthy.
"The NHS has to focus more on supporting people to manage their diabetes through self care," she added. "For people with diabetes, 95% of diabetes management is self care."