Britain's poorest communities are 2.5 times more likely to develop Type 2 diabetes than the general population, research suggests.
Diabetes is linked to obesity
They are also 3.5 times more likely to develop serious complications of diabetes, including heart disease.
The report, by the charity Diabetes UK and the All Party Parliamentary Group for Diabetes, calls for action to tackle social inequalities.
But the government said much had already been done.
The report warned there are areas where poor care and unhealthy lifestyles mean there is already a "forgotten generation" who could be condemned to a future of poor health.
Obesity is nearly 50% higher in women from poorer areas and people from these areas are also 50% more likely to smoke.
The report said about three million people were expected to suffer from diabetes by 2010, with about half of these coming from disadvantaged communities.
Lack of checks
The report found that following diagnosis, people in deprived communities do not get the health checks they need to prevent complications developing.
For example, they are less likely to have their blood glucose levels or blood pressure monitored or checks for retinopathy, which can cause blindness, and neuropathy, which can lead to amputation.
DIABETES AND THE DISADVANTAGED
In the North East of England diabetes is 45% higher in women and 28% higher in men than the national average
People from black and minority ethnic groups up to six times more likely to develop diabetes
20% of people with a severe mental illness have diabetes
Prevalence in nursing homes is up to 25% - compared to 3% in the general population
Diabetes UK chief executive Douglas Smallwood said: "With late diagnosis, poor care and poor lifestyles compounding the difficult task of managing diabetes, people in deprived communities have a bleak future.
"The diagnosis of diabetes exacerbates existing problems for people in diverse groups, who may already be struggling to cope.
"It will take a huge shift in both attitudes and services to reverse this pattern for future generations."
All Party Parliamentary Group for Diabetes chairman Adrian Sanders said government initiatives to tackle diabetes were designed to help people manage their own condition.
But he said: "If people aren't accessing this care or social barriers are preventing them from accessing care, their condition is likely to deteriorate."
The report calls for urgent action, including local plans and awareness campaigns to target at-risk groups.
It also says funds should be made available specifically to address inequalities in access.
A Department of Health spokesman said the government had tried to tackle the problem on several fronts, of which the National Service Framework for diabetes was just one.
However, he said: "Certain sections of our society are more at risk from diabetes.
"That is why we are working with Black and Asian communities to prevent heart disease by encouraging healthier lifestyles.
"We are aware of the adverse impact deprivation can have on diabetes, so have established Spearhead Trusts in these areas to provide additional resources and improve healthcare."
There are 2.2 million people diagnosed with diabetes in the UK and up to 750,000 people who have the condition but do not know it.
Type 2 diabetes, or diabetes mellitus, is a condition in which the amount of glucose (sugar) in the blood is too high because the body cannot use it properly.