1% have diabetes that is either undiagnosed or unrecorded on diabetes registers. Sixhundred thousand people are failing to receive structured care and follow-up for a serious chronic condition, even in a country with a highly developed health care infrastructure. Other estimates put the figure closer to a million. Adding still further to this problem, large numbers with borderline blood glucose levels are unidentified and likely to suffer highly preventable cardiovascular events. It is this group that are particularly likely to benefit from interventions to prevent diabetes and macrovascular disease.

Raising awareness

Much publicity has been aimed towards the general public to improve early diagnosis of diabetes. This involves two strategies (Box4.3). Firstly, people shouldbe made aware ofthe symptoms of diabetes, so that they report them to their health professionals; and secondly, patients in high-risk groups based on ethnicity, family history or other factors should be made aware of arrangements for case finding through regular testing.

Box 4.3 Cornerstones of early diabetes detection

• Raised awareness of the importance of early detection among the general public and health professionals

• Low threshold for investigating potential diabetes symptoms

• Effective follow-up of borderline blood glucose levels (see Box 4.4)

• Active case finding in high-risk groups

• Regular surveillance in selected patients

Case finding for diabetes

Active measures to detect the 'missing population' with type 2 diabetes include patient awareness raising, e.g. posters encouraging the public to report symptoms of thirst or polyuria, or to be tested if a family history or other risk factors are present. Health professionals can ensure that people at risk of undiagnosed diabetes are invited for testing (Box 4.4). This includes the following groups:

• Those with features of the metabolic syndrome, see Box 4.1

• Those with established cardiovascular disease or hypertension, who should have a blood glucose test in some form done every 3 years. Any random value 6.1mmol/l or higher should be followed up with a fasting test and/or HbA1c

• Those with a family history of type 2 diabetes, particularly in a first-degree relative

• Ethnic groups, e.g. South Asian, Afro-Caribbean, Hispanic, Pacific Islander

Investigation of suspicious symptoms

The diagnosis of diabetes is often missed simply because the condition is not considered as a diagnostic possibility when the individual reports symptoms. Particular settings when this may occur include:

• Failure to include blood glucose measurement in the assessment of tiredness, weight loss or urinary symptoms

• Investigation of urinary symptoms using a midstream specimen of urine (MSU) that excludes infection but does not include urinalysis for glucose

• An assumption that the patient's symptoms are due to prostatic disease, urinary infection, or bladder instability

This problem often affects type 2 patients whose symptoms develop gradually and are frequently attributed to ageing. But an alarming number of type 1 patients are also diagnosed late, and are then at risk of life-threatening ketoacidosis.

Box 4.4 Using primary care databases to identify undiagnosed diabetes

A study published in 2008 Holt et al. demonstrated the use of routinely collected general practice data to identify patients at risk of undiagnosed diabetes. The investigators simply looked for raised blood glucose readings in primary care electronic health records. Out of 3.6 million records examined, 0.1% of patients had no diagnosis of diabetes and a random blood glucose level at the most recent measurement >11.1mmol/l, or a fasting level >7.0mmol/l. This computer search was termed 'Strategy A'. When projected to the UK population this would amount to 60,000 individuals. A further Strategy 'B' used a lower threshold of 7.0 mmol/l (random or fasting) for the most recent reading, and identified 0.9% of the survey population, projecting to 528,000 individuals nationwide. Some of these people will have had the reading taken recently and be in the usual process of follow up. But in over a third of the 'A' patients and half of the 'B' patients, the last recorded value was more than 1 year ago. Some of these people may belong to the missing population with diabetes. As a result of this study, computer software was designed and installed in the majority of UK practices to assist practitioners in identifying them.

Time since last blood glucose measurement

Time since last blood glucose measurement

<2 2-4 5-7 8-12 13-26 27-52 1-2 >2 weeks weeks weeks weeks weeks weeks years years ago ago ago ago ago ago ago ago

Time interval

Proportion of blood glucose measurements identified by strategies A and B according to time interval since the measurement.


Type 2 diabetes develops gradually and produces non-specific symptoms, so is often diagnosed late. There is a large missing population with undiagnosed diabetes, and an even larger population with the 'metabolic syndrome', at risk of both diabetes and cardiovascular disease. Opportunities are missed to reduce cardiovascular risk in such patients, whose typically raised body mass index, waist circumference, hypertension and hyperlipidaemia should make them easy to recognise in health care settings. Active programmes of weight reduction, nutritional management and physical activity are proven to reduce progression to diabetes in those at risk, and should be widely promoted. Early detection and intervention are the only means through which the epidemic of diabetes and associated cardiovascular disease can be curtailed. It is among the most important health care challenges of our time.

Further reading

Cali AMG, Caprio S. Prediabetes and type 2 diabetes in youth: an emerging epidemic disease? Curr Opin Endocrinol, Diabetes Obesity 2008;15: 123-7.

Danaei G, Lawes CMM, Vander Hoorn S, et al. Global and regional mortality from ischaemic heart disease and stroke attributable to higher-than-optimum blood glucose concentration: comparative risk assessment. Lancet 2006;368:1651-9.

Diabetes Prevention Program Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New Engl J Med 2002;346:393-403.

Gsde P, Vedel P, Larsen N, et al. Multifactorial intervention and cardiovascular disease in patients with type 2 diabetes. N Engl J Med 2003;348: 383-93.

Gillies CL, Abrams KR, Lambert PC, et al. Pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance: systematic review and meta-analysis. BMJ 2007;334: 299.

Holman R. Assessing the potential for a-glucosidase inhibitors in prediabetic states. Diab Res Clin Pract 1998; 40(Suppl 1): S21-5.

Holt TA, Stables D, Hippisley-Cox J, et al. Identifying undiagnosed diabetes: cross-sectional survey of 3.6 million patients' electronic records. Br J Gen Practice 2008;58:192-6.

Martinez-Gonzalez MA, de la Fuente-Arrillaga C, Nunez-Cordoba JM. Adherence to Mediterranean diet and risk of developing diabetes: prospective cohort study. BMJ 2008;336:1348-51.

Tuomilehto J, Lindstrom J, Eriksson JG, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. NEngl J Med 2001;344:1343-50.

Wild S, Roglic G, Green A, et al. Global Prevalence of Diabetes: Estimates for the year 2000 and projections for 2030. Diabetes Care 2004;27: 1047-53.

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