Almost one in three diabetic hospital patients are victims of medication errors that can cause dangerous blood glucose levels, a report has found.
Hospitals in England and Wales made at least one mistake per inpatient in the treatment of 3,700 diabetes sufferers in one week, data showed.
During this period, the affected patients succumbed to more than double the number of severe hypoglycaemic, or "hypo", episodes that patients without errors suffered, according to the National Diabetes Inpatient Audit.
Hypos occur when blood glucose levels drop dangerously low and if left untreated can lead to seizures, coma or death.
In addition, 68 patients developed diabetic ketoacidosis (DKA) during their stay in hospital.
DKA occurs when blood glucose levels are consistently high and can be fatal if not treated.
This suggests that insulin treatment was not administered for a significant period of time, the report said.
According to the findings, 32 per cent of patients (3,430) experienced at least one medication error in the previous seven days of their hospital stay.
This was a small improvement on the previous year, when the figure was 36.6 per cent, or 4,120.
The most common errors involved failing to sign off on the patient's bedside information chart that insulin had been given, which happened to 11.1 per cent of patients (440), and failing to appropriately adjust medication when the patient had a high blood sugar level, which happened to 23.9 per cent (800).
More than 17 per cent (600) of patients with medication errors had a severe hypoglycaemic attack while in hospital, compared to 7.5 per cent (550) of patients who did not suffer medication errors.
The report also found:
:: Almost a third (30.6 per cent) of patients who responded to a patient experience questionnaire said they had not been able to take control of their own diabetes while in hospital as much as they would have liked to.
:: More than 13 per cent of patients said the hospital did not provide the right type of food to manage their diabetes.
:: Almost 10 per cent of inpatients with diabetes had been on an insulin infusion in the past seven days of the audit period but the healthcare professionals collecting the data suggested that 10 per cent of these patients were inappropriately given the infusions.
:: Specialist staffing levels were lower than recommended.
Audit lead clinician Dr Gerry Rayman, consultant physician and head of service at Ipswich Hospital NHS Trust Diabetes and Endocrine Centre, said: "Although it is pleasing to see there have been improvements in medication errors since the last audit, there is a long way to go and indeed the majority of hospital doctors and ward nurses still do not have basic training in insulin management and glucose control.
"Training needs to be mandatory to improve diabetes control and reduce the frequency of severe hypoglycaemia.
"It is also needed to prevent diabetic ketosis occurring in hospital, for which there can be no excuse.
"Its occurrence is negligent and should never happen."
Diabetes UK said the findings were an indictment of how hospitals were failing to care for people with diabetes.
Chief executive Barbara Young said: "The fact that there are so many mistakes and that for some people a stay in hospital means they get worse should simply not be happening.
"Poor blood glucose management, caused by errors in hospital treatment, is leading to severe and dangerous consequences for too many people.
"Although we know that some excellent steps have been taken, including courses and online tools, to increase knowledge and education among healthcare staff for the treatment of people with diabetes on hospital wards, we are not seeing good enough results from this yet.
"The fact that the situation has barely improved in the last year shows that the NHS is not yet taking this seriously enough.
"Urgent action is needed to make sure that general ward staff are competent and confident about treating inpatients with diabetes."
The audit was managed by the Health and Social Care Information Centre in partnership with Diabetes UK, and commissioned by the Healthcare Quality Improvement Partnership.
It examined bedside data for 12,800 patients and 6,600 patient questionnaires, covering subjects including medication errors and patient harm over a seven-day period in October 2011.
It involved 11,900 patients in 212 English hospitals and 900 patients in 18 Welsh hospitals.
The Department of Health (DH) said medicine management has improved since 2010 but admitted there are still too many errors.
A DH spokesperson said: "We will continue to work with clinicians to reduce errors so patients can be confident that the medicines they receive are safe and appropriate."