A quarter of a million individuals with dementia are being let down by the home care, according to a report by the Alzheimer's Society.
Fifty per cent of carers said the patient was not receiving enough care and support and reports were made of people being left in bed and malnourished.
According to the report, entitled "Support. Stay. Save. Care and support of people with dementia in their own homes", this lack of care will drive 50,000 people with dementia into care homes earlier than they otherwise would have.
In addition, for each extra month they remain in a care home, the state will face a bill of £70 million.
Jeremy Hughes, chief executive of Alzheimer's Society said: "It is an absolute travesty that so many people with dementia are being forced to struggle without the care and support they need. The consequences of this represent an unacceptable human and financial cost."
This comes after Age UK said that care for older people should be at the heart of NHS reforms, with the UK's life expectancy continuing to rise.