National Diabetes Audit 2021-22, Young People with Type 2 Diabetes - Detailed Analysis Report

This page provides further information on some of the methodological elements of the report.

The National Diabetes Audit (NDA) and the National Paediatric Diabetes Audit (NPDA) provide a comprehensive view of diabetes care in England and Wales. They measure the effectiveness of diabetes healthcare against National Institute for Health and Care Excellence (NICE) Clinical Guidelines and NICE Quality Standards.

The NDA is conducted by NHS England. It is funded by the Department of Health and Social Care through the Healthcare Quality Improvement Partnership (HQIP). The Core NDA includes data recorded on people of all ages with diagnosed diabetes in England and Wales. The audit is conducted on an annual basis, with partial year data from general practices (GPs) in England published on a quarterly basis.

Further information on the NDA can be found on the Core National Diabetes Audit webpage. For information on the NDA data collection process and for further details on the analysis of areas such as care processes, see the Methodology section of the National Diabetes Audit 2021-22, Report 1: Care Processes and Treatment Targets, Detailed Analysis Report.

Although the NDA collects data for all ages from primary care and specialist diabetes services, it does not specifically collect data from specialist paediatric diabetes units. The Royal College of Paediatrics and Child Health (RCPCH) is commissioned to deliver the National Paediatric Diabetes Audit (NPDA).

The NPDA is conducted by the RCPCH. It is funded by the Department of Health and Social Care through HQIP. The NPDA is an audit of the care processes received and outcomes achieved by all children and young people attending paediatric diabetes units in England and Wales and is conducted annually.

Further information on the NPDA can be found here: RCPCH - NPDA

The NDA and NPDA datasets have previously been linked for the Adolescent and Young Adult Type 1 Diabetes Audit (AYA). The AYA has been designed to audit care provision during the period when young people with diabetes move from paediatric to adult based clinical care. The latest AYA report can be found here: Adolescent and Young Adult Type 1 Diabetes Audit (AYA), 2017-21.

Linkage for this report on young people with type 2 diabetes has been carried out in the same way as for AYA. This is done on NHS number, as this is a compulsory field in both the NDA and the NPDA.

The cohort of young people with type 2 diabetes used in this report differs from that used in NDA Core Report 1 for 2021-22. The NDA can receive data on one person from multiple GPs and specialist diabetes services. These sources do not always concur on details such as a person’s diagnosed diabetes type. Where differences occur, an algorithm is used within the NDA to decide which diabetes type should be assigned (for further information see Methodology in the NDA Core Report 1 2021-22 detailed report). The introduction of the NPDA as an additional source requires further decisions to be made on who to include in a cohort of young people with type 2 diabetes. Following discussion and analysis of the data, the clinical advisory group for this audit decided on the following.

This cohort of young people with type 2 diabetes consists of people:

• Recorded as having type 2 diabetes in NPDA for the audit year (1)
• Whose recorded diagnosis (2) and/or HbA1c and/or drug prescription information (3) indicates a person has type 2 diabetes in NDA in the audit year (4)
• In England or Wales (5)
• Aged under 40 years, split into the following groups: under 12 years; 12 to 15 years; 16 to 18 years; 19 to 25 years; 26 to 39 years (6)

The flow chart below defines the young people with type 2 diabetes cohort (7). The same methodology is used to define the cohort for each of the audit years in this report.

The drugs categorised as ‘insulin’ are:

• Intermediate cartridge
• Intermediate pre-filled pen
• Intermediate vial (8)
• Long-acting cartridge
• Long-acting pre-filled pen
• Long-acting vial (8)
• Mixed cartridge
• Mixed pre-filled pen
• Mixed vial
• Soluble cartridge
• Soluble pre-filled pen
• Soluble vial

The drugs categorised as ‘metformin’ are:

• Metformin
• Metformin composite

The drugs categorised as 'other oral hypoglycaemics' (9) are:

• α-glucosidase inhibitors
• DPP-4 inhibitors/Gliptins
• Glinides/Meglitinides
• GLP-1 receptor agonists
• Guar
• Insulin/GLP-1 receptor agonist combination
• SGLT2 inhibitors
• Sulphonylureas
• Thiazolidinediones
• 'Other' oral hypoglycaemic drugs

Prescription data for Semaglutide (GLP-1 receptor agonist), Ertugliflozin (SGLT2 inhibitor), Empagliflozin with linagliptin (SGLT2 inhibitor with DPP-4 inhibitor), and Saxagliptin with dapagliflozin (DPP-4 inhibitor with SGLT2 inhibitor) has not been included within the NDA drugs data collection. Therefore these drugs have not been included in the cohort for this report.  This means that individuals may have been omitted from the cohort when they should have been included.  Work is ongoing to ensure all glucose-lowering medications are collected and included in future publications.

Notes:

1. The NPDA audit year runs from 01 April the first year to 31 March the following year. For example, the audit year 2021-22 covers the period 01 April 2021 to 31 March 2022.

2. In the derived NDA central data set that uses all audit period data from 2003-4 to 2021-22 to select a person’s diabetes type, based on a set of rules that have been agreed with lead clinicians.

3. Includes intermediate and long acting insulin in a vial. These were not included in the cohort definition for the 2019-20 report.

4. The NDA audit year runs from 01 January the first year to 31 March the following year. For example, the audit year 2021-22 covers the period 01 January 2021 to 31 March 2022.

5. This means either:

• They were registered at a GP in England or Wales during the audit period and have a diabetes diagnosis in their GP records (NDA);
• They attended a specialist diabetes service in England or Wales during the audit period (NDA); or
• They attended a paediatric diabetes unit in England or Wales during the audit period (NPDA).

6. In this report, for certain analyses those aged under 40 years were compared to the following  ’40 years and over’ age groups: 40-59 years; 60-79 years.

7. For older cohorts (40-59 and 60-79 years) people in the NDA and NPDA are only included if they are recorded as having type 2 diabetes in their respective audits.

8. This was not included in the cohort definition for the 2019-20 report.

9. Metformin is an oral hypoglycaemic also but due to its’ clinical significance to the analysis it is categorised separately.

The BMI categories used in this report have been calculated in different ways.

British 1990 growth reference (UK90) is used to define the BMI categories. This approach is recommended by NICE and is used in the NPDA. In addition to height and weight, the age and sex of the child is used for the comparison to these growth reference charts. Each child’s BMI is calculated from height and weight and compared to the distribution for the relevant age and sex in children in 1990. Which centile the child equates to is used to categorise BMI according to the table below.

BMI has been calculated using height and weight for adults. Each person is then assigned a category dependant on their ethnicity, as per the table below. This is in line with the NHS England Weight Management Programme and recent research in the field (1).

Notes:

1. Caleyachetty and others. Ethnicity-specific BMI cutoffs for obesity based on type 2 diabetes risk in England: a population-based cohort study, The Lancet Diabetes and Endocrinology 2021; 9(7):419-426

Data from the Census 2021 was used in this report to provide comparative figures for the general population in England and Wales.

The Census 2021 took place on 21 March 2021. It was run by the Office for National Statistics (ONS) and they were responsible for disseminating census statistics for both England and Wales.

Statistics from the census help paint a picture of all the people and households in England and Wales and how they live. They provide a detailed snapshot of the population and its characteristics and underpins funding allocation for public services.

For further information see ONS - Census.