National Diabetes Inpatient Safety Audit 2024-25

The National Diabetes Inpatient Safety Audit (NDISA) is part of the National Diabetes Audit (NDA) which undertakes a continuous collection of serious inpatient harms that can affect people with diabetes.

This collection was previously known as the National Diabetes Inpatient Audit (NaDIA) harms audit. Data collection began on 1 May 2018. All acute hospitals in England and Wales with inpatients with diabetes are eligible to participate. Welsh providers were invited to submit to NDISA in November 2022 and 1 of 7 Welsh local health boards (LHBs) have since participated.

The NDISA collects data on the frequency of 4 avoidable inpatient diabetes harms collected in NDISA:

1) Hypoglycaemia:

Note: The definition of hypoglycaemia used in NDISA changed on 1 April 2024:

• Prior to 31 March 2024: Hypoglycaemic rescue: Did the patient require injectable rescue treatment for an episode of hypoglycaemia starting more than 6 hours after admission?
• From 1 April 2024 onwards: Severe inpatient hypoglycaemia (< 2.2 mmol/l): Did the patient experience severe hypoglycaemia 6 or more hours into their hospital admission?

2) Diabetic ketoacidosis (DKA): Was the patient diagnosed with new onset DKA more than 24 hours after admission?

3) Hyperglycaemic hyperosmolar state (HHS): Was the patient diagnosed with new onset HHS more than 24 hours after admission?

4) Diabetic foot ulcer: Was the patient diagnosed with a new onset foot ulcer more than 72 hours after admission?

The main objective of the NDISA harms collection is to monitor and help reduce the rates of these serious inpatient harms.

The NDISA 2024-25 release is a detailed analysis file with information on inpatient harms collected in NDISA between November 2018 and October 2025. Results are split into 3 sections:

1. NDISA: Inpatient harms participation
2. NDISA: Inpatient harms counts
3. NDISA: Inpatient harms rates

Sections 2 to 3 use NDISA harms data linked to the core NDA and Hospital Episode Statistics (HES).

The NDISA 2024-25 release will be of interest to the public, especially to people with diabetes. Health planners and policy makers, as well as acute NHS Trusts, integrated care boards (ICBs), LHBs, integrated care systems (ICSs), sustainability and transformation partnerships (STPs), clinical networks (CNs; formerly strategic clinical networks or SCNs) and other providers and commissioners of specialist diabetes services will also make use of the information in this report.

Patients in the NDISA harms collection were linked to data items recorded in the core NDA, including NDA data up to 30 September 2025. Linkage included data from the incomplete core NDA audit year 2025-26 for England only (1 April 2025 to 30 September 2025). NDA data covering April to September 2025 is therefore provisional.

The core NDA collects data on patient demographics, care processes and treatment targets amongst those registered with participating GP practices and secondary care organisations in England and Wales. GP practice participation in England and Wales was 99% in the latest core NDA Report 1 for 2024-25, covering 1 April 2024 to 31 March 2025. An additional 172 specialist services in England submitted data to the collection.

94% of patients in the NDISA harms collection were found in the core NDA. Diabetes type was taken from the core NDA demographics table, supplement by new diagnoses in the incomplete core NDA audit year 2025-26 for England only (1 April 2025 to 30 September 2025).

HES is a database containing details of all admissions, outpatient appointments and accident and emergency attendances at NHS hospitals and NHS-funded private providers in England. NDISA harms patients were linked to hospital admissions data in HES, with admissions data available up to 30 November 2025. HES data covering April 2025 to January 2026 is provisional.

Hospital admissions covering the date of the inpatient harm were found for 94% of episodes in the NDISA harms collection.

Data in the inpatient harms section of the NDISA 2024-25 report are derived from inpatient harms that occurred between 1 November 2018 and 31 October 2025 (the cohort), covering 84 months of data collection. The data was extracted from the NDISA harms collection database on 28 November 2025, almost 1 month after the end of the audit period.

The NDISA 2024-25 report was published on 14 May 2026. The time lag to the publication of the detailed analysis file was therefore 6.5 months after the end of the NDISA harms cohort (31 October 2025) and 5.5 months after the data extract was taken (late November 2025).

Participation in the NDISA harms collection is mandatory for all acute NHS trusts admitting patients with diabetes in England and Wales. The Welsh government initially decided not to participate in the NDISA harms collection. Welsh providers were invited to submit to NDISA in November 2022 and 1 of 7 Welsh local health boards (LHBs) have since participated.

123 healthcare providers registered for the NDISA harms collection between 1 May 2018 and 28 November 2025. 120 of these 123 healthcare providers participated in the NDISA harms collection between 1 May 2018 and 31 October 2025. A healthcare provider is classed as having participated if they either:

1. Submitted 1 or more inpatient harm; or
2. Confirmed a nil submission for 1 or more month

during the stated period.

For comparison, 138 healthcare providers in England and Wales are known to be eligible for NDISA: 131 acute NHS trusts in England (excluding 3 acute children's trusts) and 7 LHBs in Wales. 98 of the 138 NDISA-eligible providers participated in the latest NDISA audit year (November 2024 to October 2025), suggesting a participation rate of around 71%.

20,555 inpatient harms were recorded in the NDISA harms collection during the 7 year report period (November 2018 to October 2025). Case ascertainment for each type of inpatient harm has previously been calculated using estimates derived from the 2019 National Diabetes Inpatient Audit (NaDIA) snapshot. Results were published in the 2019 NaDIA harms audit report (p. 32). Case ascertainment for DKA was estimated at 20% (DKA), with the other inpatient harms estimated at 6-8% (others).

However, the true case ascertainment is likely to be higher than the above estimates for 2 reasons:

1. The expected number of inpatient harms may be inflated by the increased likelihood of longer stay patients both experiencing an inpatient harm and being present on the NaDIA snapshot audit day; and
2. Because the latest NaDIA snapshot was undertaken in September 2019, any reduction in the number of inpatient harms since this period will not be reflected in the baseline figures.

Both of the factors above will inflate the expected number of inpatient harms, consequently reducing the case ascertainment.

Analysis covering April to October 2025 uses provisional data from both HES and core NDA. Further analysis will be required to get a complete picture of hospital activity during this period.

It should be noted that different NDISA harms cohorts are used in different parts of the NDISA 2024-25 report:

• Results are aggregated by NDISA audit year (November to October) to review NDISA participation and inpatient harms counts in sections 1 and 2.
• To review hypoglycaemia trends over time in figures 3a and 3b, results are aggregated by quarters based on the calendar year (e.g. 2020 Q1 covers 1 January 2020 to 31 March 2020), starting in 2018 Q3 and ending in 2025 Q3.
• To review DKA, HHS and diabetic foot ulcer trends over time in figures 3c to 3e, results are aggregated by calendar year (2019 to 2025). Note that 2025 is a partial year, covering 1 January to 31 October 2025.

Table 1 below shows that the number of participants per NDISA audit year has remained fairly static since audit inception (between 94 and 104).

Table 1: Number of NDISA participants per NDISA audit year, England and Wales¹, November 2018 to October 2025

Notes:

1. Welsh providers were invited to submit to NDISA in November 2022 and 1 of 7 Welsh LHBs have since participated.

Looking at the latest NDISA audit year (November 2024 to October 2025) in table 2 below:
On a monthly basis, the number of participants is always substantially less than the 102 total for the full NDISA audit year, ranging from 71 to 81. This means that not all participants submit NDISA returns every month.

Table 2: Number of NDISA participants per month, by submission type, England and Wales, November 2024 to October 2025

Table 3 shows that, overall, the participation rate amongst NDISA-eligible providers was 71% (98 of 138). Coverage by region ranged from 52% of NDISA-eligible providers in the Midlands to 93% in the South East of England. Welsh organisations were invited to submit to NDISA in November 2022 and 1 of 7 Welsh LHBs have since participated (14%).

Table 3: Number of NDISA-eligible providers that submitted to NDISA, by country and region, England and Wales, November 2024 to October 2025

Notes:

1. 131 acute NHS trusts, excluding 3 acute children's trusts, and 7 LHBs.

Of the 4 inpatient harms collected in NDISA, the large majority (80%) are hypoglycaemia. It is therefore particularly important to note that the definition of hypoglycaemia used in NDISA changed on 1 April 2024:

• Prior to 31 March 2024: Hypoglycaemic rescue: Did the patient require injectable rescue treatment for an episode of hypoglycaemia starting more than 6 hours after admission? . Consequently 2022-23 is the latest full NDISA audit year (November to October) where hypoglycaemic rescue data is available.
• From 1 April 2024 onwards: Severe inpatient hypoglycaemia (< 2.2 mmol/l): Did the patient experience severe hypoglycaemia 6 or more hours into their hospital admission? Consequently 2024-25 is the first full NDISA audit year (November to October) where severe inpatient hypoglycaemia data is available.

The two definitions of hypoglycaemia are split in all NDISA analysis and are clearly labelled as "Hypoglycaemic rescue" or "Severe inpatient hypoglycaemia (< 2.2 mmol/l)".

Audit information is held securely and with restricted access.

It is expected that, through the audit collection, all organisations will continue to follow existing NHS codes of practice about patient confidentiality, information security management, record management and other legal obligations.

Disclosure control has been applied to mitigate the risk of patient identification. Zeros are reported, and all numbers are rounded to the nearest 5, unless the number is 1 to 7, in which case it is rounded to ‘5’. This allows for more granular data to be made available, and also for data for all GP practices to be made available. Percentages where the denominator is less than or equal to 20 are not reliable and have therefore not been calculated in this release.

From 2010 to 2019 the NaDIA snapshot audit collected information on the incidence of inpatient harms during a specified week in September, including the 4 inpatient harms collected in the continuous NDISA harms collection. The latest NaDIA snapshot was carried out by hospital teams in England on a nominated day between 23 and 27 September 2019 and published in the 2019 NaDIA report published on 13 November 2020.

Inpatient harms in the NaDIA snapshot are reported as a proportion of inpatients experiencing the inpatient harm during their hospital stay (DKA, HHS, new diabetic foot ulceration) or in the previous 7 days of their hospital stay (hypoglycaemia requiring rescue treatment).

Direct comparison between the collections is difficult due to the different methodology and collection periods of the 2 collections. Comparative analysis was done for the 2020 NaDIA harms report to produce estimated case ascertainment for each inpatient harm. The results and limitations of this comparison are discussed above (in Accuracy, reliability and limitations).

No other data source provides equivalent information about the incidence of inpatient harms in England.

The NDISA 2024-25 release is a detailed analysis file in Excel format. Below are links to additional material relevant to this publication:

• The NDISA 2022-23 report. 
• Further information about the NDISA harms collection.
• Information about the superseded NaDIA harms collection. 
• The final NaDIA harms audit report from 2021.
• Information about the closed NaDIA snapshot.
• The final NaDIA snapshot report from 2019. 

The NDISA harms collection is designed to be a low-burden collection, with only 4 data items required from submitters:

• NHS number: for data validation and linkage
• Inpatient harm type: hypoglycaemia, DKA, HHS, new diabetic foot ulceration
• Date the inpatient harm occurred
• Hospital site at which the inpatient harm occurred

The audit team acknowledges that participation in the audit involves costs in both time and organisation for the providers that take part, and thanks them for their efforts. The audit continues to look at ways in which to reduce respondent burden and increase ease of participation and welcomes comments and suggestions.

NHS England are currently reviewing the routine production of NDA State of the Nation reports. Please note that data will still be released via dashboards and standalone data files whilst this review is being conducted.

To help inform this review we would be grateful if users can provide feedback on their use of the State of the Nation reports using the feedback survey available in the ‘Related links' section of this page.