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Publication, Part of

Health Survey for England, 2021 part 2

Official statistics, National statistics, Survey

National Statistics
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Adults' health: Diabetes



Diabetes is characterised by high blood glucose levels (hyperglycaemia).

Untreated, hyperglycaemia is associated with damage and possible failure of many organs, especially the eyes, kidneys, nerves, heart, and blood vessels. Diabetes substantially increases the risk of cardiovascular disease (CVD) and tends to worsen the effect of other risk factors for CVD, such as abnormal levels of blood fats, raised blood pressure, smoking and obesity (Garcia et al, 1974).

Diabetes mellitus (both Types 1 and 2) is a leading cause of avoidable mortality. The 2017/18 National Diabetes Audit report, which focused on complications and mortality, estimated that the additional risk of death each year among people with diagnosed diabetes in England and Wales was 53%, with the highest risk in those with Type 1 diabetes (Source: National Diabetes Audit 2017-18).

Methods and definitions


HSE measures diabetes in two ways. The prevalence of self-reported doctor-diagnosed diabetes is included in the main interview.

In addition to the interview question, glycated haemoglobin (HbA1c) levels are measured in blood samples collected at the nurse visit. HbA1c reflects average blood sugar levels over the previous two to three months and can therefore be used both to monitor diabetic control in people with diagnosed diabetes, and to detect undiagnosed diabetes (Source: World Health Organization).


The presence of doctor-diagnosed diabetes is identified if a participant answers yes to two questions.

  • Do you now have, or have you ever had, diabetes?
  • Were you told by a doctor that you had diabetes?

This report does not distinguish between Type 1 and Type 2 diabetes.

Further information about Type 1 and Type 2 Diabetes

In earlier years (up to HSE 2003), it was assumed that participants who reported having doctor-diagnosed diabetes before the age of 35 and who were having insulin therapy at the time of the survey had Type 1 diabetes, and all other participants with doctor-diagnosed diabetes were classified as having Type 2 diabetes. However, increasing numbers of people are now being diagnosed with Type 2 diabetes below the age of 35 and some adults with Type 2 diabetes are now prescribed insulin therapy, so these distinctions are no longer reliable.  

Total diabetes in the population includes all participants who reported having doctor-diagnosed diabetes, as well as those with a blood sample measured as having an HbA1c level of 48mmol/mol or above, diagnostic of diabetes. Among those with total diabetes, participants with a raised HbA1c who did not report having doctor-diagnosed diabetes are defined as having undiagnosed diabetes.  

Further information on diagnosed and undiagnosed diabetes

The prevalence of diagnosed and undiagnosed (total) diabetes is presented from 2011 onwards. Values of HbA1c were adjusted in 2013 (4th quarter) and each year from 2014 onwards to make them comparable to previous data, due to changes in calibrators. 

Further details of the protocols for collecting measurements and blood samples can be found in the HSE 2021 Methods report.

Prevalence of doctor-diagnosed diabetes, by age and sex

In 2021, 6% of adults reported that a doctor had told them that they had diabetes.

The prevalence of doctor-diagnosed diabetes was higher among men (7%) than women (5%). Prevalence increased with age, from 1% of adults aged under 35 to 16% of adults aged 75 and over.

For more information: Table 3

Prevalence of total diabetes, by age and sex

Estimates of the prevalence of total diabetes, using glycated haemoglobin levels, are limited to participants with a nurse visit and a valid HbA1c measurement.

Consequently, the estimates of those with doctor-diagnosed diabetes in Tables 4 to 7, which are limited to only those with a blood sample, vary slightly from those in Table 3, which shows the definitive estimates.

10% of adults had total diabetes; this comprised 7% with doctor-diagnosed diabetes and a further 3% with undiagnosed diabetes.

The prevalence of total diabetes was higher among men (12%) than women (8%).

For more information: Table 4

The prevalence of total diabetes increased with age, from 5% of adults aged 16 to 44 to 21% of adults aged 65 and over.

For more information: Table 4

Prevalence of total diabetes, by income

The HSE uses the measure of equivalised household income, which takes into account the number of adults and dependent children in the household, as well as overall household income. For this section of the report, households are divided into tertiles (thirds) based on this measure. The age profile of the income tertiles have been age-standardised to account for differences in age profiles between households. Previous years have divided households into quintiles, but this was not possible for HSE 2021 owing to smaller numbers. Some differences across income groups have been observed in previous years with more groups for analysis.

For information about how equivalised income is calculated, see the HSE 2021 Methods report.

The age-standardised prevalence of total diabetes was similar across the equivalised income tertiles.

For more information: Table 5

Prevalence of total diabetes, by area deprivation

The Index of Multiple Deprivation (IMD) is a measure of area deprivation, based on 39 indicators, across seven domains of deprivation. IMD is a measure of the overall deprivation experienced by people living in a neighbourhood, although not everyone who lives in a deprived neighbourhood will be deprived themselves. To enable comparisons, areas are classified into quintiles (fifths). For further information about the IMD, see the HSE 2021 Methods report.

The age-standardised prevalence of total diabetes was similar across the IMD quintiles.

For more information: Table 6

Doctor-diagnosed diabetes

The proportion of adults with doctor-diagnosed diabetes increased between 1994 and 2009, from 3% to 7% among men and from 2% to 5% among women. Between 2010 and 2019, the proportion varied between 6% and 9% of men and 5% and 6% of women.

For more information: Table 3

Total diabetes

Levels of total diabetes, as identified through HbA1c levels, have varied in the years 2011 to 2019 between 9% and 11% among men, and between 6% and 9% among women, with no clear pattern.

The prevalence of undiagnosed diabetes has been consistent at between 2% and 4% since 2011.

For more information: Table 7

Last edited: 16 May 2023 9:31 am