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Early identification of people with Type 2 diabetes

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  • 1. 10 Parkway London NW1 7AA Tel 020 7424 1000 Fax 020 7424 1001 Email info@diabetes.org.uk Website www.diabetes.org.uk Position Statement Early identification of people with Type 2 diabetes June 2006 Page 1 of 10 Diabetes UK has for many years been calling for the establishment of active programmes to identify people with Type 2 diabetes early, to ensure appropriate diabetes care and treatment. Those at increased risk of Type 2 diabetes should be targeted as part of systematic case finding, annual health checks and Cardiovascular Disease Risk Management Programmes. The objectives of such initiatives are to reduce the numbers of people with undiagnosed diabetes, the burden of complications at diagnosis, the impact on the person with diabetes and the impact of diabetes on NHS resources. Raising awareness of risk factors amongst the population, alongside the development of targeted programmes to identify those at high risk of developing Type 2 diabetes would go a long way towards reducing the devastating and costly complications of coronary heart disease, renal disease, blindness, stroke and foot disease.(1) UKPDS shows that up to 50 per cent of people diagnosed with Type 2 diabetes presented with developing complications at diagnosis particularly retinopathy.(2) Evidence is also available showing that there is a long and latent asymptomatic period in which the condition can be detected.(3) Impaired glucose tolerance is associated with an increased risk of premature cardiovascular disease and early management may reduce progression to diabetes. Increased awareness and prioritisation of diabetes within policy initiatives, such as the national diabetes frameworks, new General Medical Services and Pharmacy contracts, have had a positive impact on the extent to which local health services are actively seeking to identify people with diabetes early. Diabetes UK/Dr Foster 2005 research has shown that 60% of localities in England have programmes in place to identify people with diabetes early.(4) However, it is estimated that approximately 0.75 million people with diabetes remain undiagnosed in the UK.(5) With the The charity for people with diabetes Diabetes UK is the operating name of the British Diabetic Association Company limited by guarantee Registered office: 10 Queen Anne Street, London W1M 0BD Registered in England no. 339181 Registered charity no. 215199
  • 2. Early identification of people with Type 2 diabetes Page 2 of 10 expectation that the number of people with diabetes will reach 3 million by the end of the decade, further action is needed to ensure that people with diabetes are identified early. National Policy development In 2002, the Department of Health(1) recognised that there was a case for a more systematic approach to screening for Type 2 diabetes and commissioned a review of research. As part of this work, the Diabetes Heart Disease and Stroke (DHDS) Pilot Project, under the auspices of the National Screening Committee (NSC)(6), was established to test the implications and outcomes of implementing a systematic programme in primary care, serving populations at greatest risk. The NSC and Department of Health (DH) received feedback from all representatives undertaking DH commissioned research. The evidence presented led to a consensus for the need for an integrated approach combining Cardiovascular Disease (CVD) and diabetes to focus on the person and provide holistic care, rather than on single risk factors. In February 2006, the NSC recommended that diabetes be included in a Risk Assessment and Control [Management] Programme(6) to ensure all people with known vascular disease, high blood pressure or diabetes receive a comprehensive risk assessment and risk reduction therapy, to reduce the burden of stroke, diabetes and coronary heart disease for individuals and populations. Testing for diabetes in a subset of the population will be included in this future programme. Those identified as having Type 2 diabetes should have active management of their diabetes as well as support to reduce other risk factors for vascular disease. Action Diabetes UK welcomes the NSC announcement that those at high risk of diabetes will be systematically screened within a CVD risk management programme(s) and is pressing for: • the National Screening Committee to publish its research findings, specific selection criteria and implementation details. • local commissioning bodies and professionals to establish programmes and initiatives to screen those at increased risk of diabetes to identify positive diagnoses. • more public education about the risk factors of diabetes and links with cardiovascular disease Prior to publication of the research, and in the absence of a single national protocol, Diabetes UK recommends, based on current consensus, the following criteria to support healthcare professionals and commissioning bodies to implement protocols.
  • 3. Early identification of people with Type 2 diabetes Page 3 of 10 Care Recommendations: Early identification of diabetes These recommendations relate to early identification of people with possible elevated blood glucose and not to diagnosis. Diagnosis of diabetes must be confirmed by an appropriately qualified healthcare professional following further testing using accredited laboratory services, in line with World Health Organisation (WHO) diagnostic criteria http://www.diabetes.org.uk/infocentre/carerec/newdiagnotic.htm Diabetes UK expects the National Screening Committee to publish evidence and criteria later in 2006. Please Note: If a person has any symptoms suggestive of diabetes, but none of the risk factors apply, further investigation is necessary. 1. Whom to test General population screening is not recommended. The mean prevalence of known diabetes in the +40 age group is between two and five per cent, the great majority having Type 2. An equal number are undiagnosed.(7) Prevalence of diabetes in Asians over the age of 40 has been shown to be as high as 20 per cent.(8) Presence of a risk factor for diabetes (obesity, large waist circumference, family history, Asian/African origin etc) improves the performance of all screening tests. Over 80 percent of people with Type 2 diabetes are overweight at diagnosis and the more overweight a person is, the greater the risk of diabetes.(9) Therefore, targeted case finding of high risk groups should be encouraged. This may be done most economically and effectively as part of other health care examinations, such as screening for cardiovascular risk factors. As a result of research, waist circumference is now a recognised risk predictor for diabetes, in addition to the established BMI measurement. 2. Risk factors and people most at risk of developing diabetes The more risk factors a person has, the more likelihood of being at risk of diabetes and the higher the sensitivity and specificity of a screening test. Evidence is not currently strong enough to weight individual risk factors. Just being over 40 years if White, or 25 years if Black, Asian or of ethnic origin is not a risk factor in itself. Therefore clinical judgement should also used in assessing the level of risk of each individual. For example there may be individuals who do not meet the age criteria but have other risk factors eg an obese child who has a strong family history of diabetes. Raising awareness of the general public about the risk factors and signs and symptoms of diabetes should also be incorporated as part of any screening programme to try and ensure the participation of those most at risk. Criteria for screening for diabetes within targeted populations
  • 4. Early identification of people with Type 2 diabetes Page 4 of 10 Diabetes UK recommends that the following people should be offered screening for diabetes a) White people aged over 40 years and people from Black, Asian and minority ethnic groups aged over 25 with one or more of the risk factors below: − a first degree family history of diabetes and/or − who are overweight/obese/morbidly obese with a BMI of 25-30 kg/m2 and above(8,9), and who have a sedentary lifestyle (Though more accurate than body weight alone, body fat may be overestimated in people who are very muscular or underestimated in those who have lost muscle mass using BMI) and/or − Waist measurement of over > 94cm (> 37 inches) for White and Black men and > 80cm (> 31.5 inches) for White, Black and Asian women, and > 90cm (> 35 inches) for Asian men.(10-15) b) People who have ischaemic heart disease, cerebrovascular disease, peripheral vascular disease or treated hypertension(16) c) Women who have had gestational diabetes who have tested normal following delivery (screen within 6 weeks of delivery and then 1 year post-partum and then three-yearly) (17) d) Women with polycystic ovary syndrome who have a BMI > 30 (18) e) People who are known to have impaired glucose tolerance or impaired fasting glycaemia. (19,20) f) People who have severe mental health problems. (21, 22, 23) g) People who have hypertriglyceridemia not due to alcohol excess or renal disease.(24) 3. Testing methods There is currently limited evidence available to identify the most effective and practical method of screening for Type 2 diabetes. Postprandial urinalysis for glycosuria is less sensitive and is thus not strongly recommended. Random blood glucose values are difficult to interpret unless they are clearly diagnostic of diabetes. Fasting venous blood glucose measurement has been shown to have a higher sensitivity and specificity than capillary testing. However, it is recognised that fasting capillary blood testing may be more convenient for use in general practice and pharmacies, although this will miss 20-30 per cent of cases. See Appendix 1 for detail on all methods of screening. Diabetes UK recommends that fasting capillary or venous blood glucose measurement should be the preferred screening method. It must be noted that certain blood glucose meters which use capillary blood, convert the result to give a plasma, rather than a whole blood reading. Plasma has a proportionally higher water content than whole blood. This results in plasma having a higher reading than whole blood. Therefore when using a finger prick test the person doing the test should be aware of the measure the result is given in.
  • 5. Early identification of people with Type 2 diabetes Page 5 of 10 • Fasting whole blood and plasma blood tests Fasting Results in mmol/l < 5.6 whole blood Low probability of diabetes Advice and information about (capillary/venous) healthy living and reduction of risk factors <6.1 Plasma Rescreen as clinically indicated 5.6-6.0 whole blood Probability of impaired Refer to GP (as appropriate) (capillary/venous) fasting glycaemia Perform OGTT to rule out 6.1-6.9 Plasma diabetes 6.1-11.0 whole blood Probability of diabetes Refer to GP (as appropriate) (capillary/venous) Perform OGTT to rule out 7.0-12.1 Plasma diabetes > 11.1 whole blood High probability of diabetes Refer to GP (as appropriate) (capillary/venous) Perform OGTT to rule out > 12.2 Plasma diabetes Fasting tests are best done first thing in the morning before breakfast. This is probably the most useful test at the present time although it has not proved popular with patients, having a relatively low compliance rate. • Random whole blood (capillary or venous) and plasma capillary testing can be misleading and, if used, appropriate feedback to patients is essential. A person with a test result > 11.1 mmol/l (Plasma > 12.2 mmol/l) should receive further confirmatory and diagnostic tests at the earliest opportunity. If a pharmacy is testing, referral should be made to the GP. If levels are between 5.6 and 11.0 mmol/l then perform a fasting blood glucose test. This is probably best done by the GP, where the laboratory results can be taken as the first of the two required diagnostic tests.(25) 4. Blood glucose measurement Screening may be performed using a suitable quality-controlled laboratory or standardised near- patient method. Regular checks of the equipment and the technique of the screener must be made. However, the diagnosis of diabetes must be based on an accredited laboratory method. No treatment should be started on the basis of a screening result. 5. How often to test Diabetes UK currently recommends active case finding of those with increased risk of developing diabetes every three years.(26)
  • 6. Early identification of people with Type 2 diabetes Page 6 of 10 6. Where to test Screening is probably most cost-effective when performed as part of a general health review in primary and community care services, when other cardiovascular risk factors can be measured for example and appropriate advice is immediately available. However, Diabetes UK supports services being organised within other venues, such as pharmacies, provided staff are appropriately trained and services are protocol driven. Clear referral guidelines and good medical support are essential if screening is performed outside general practice. In certain circumstances, such as screening within ethnic communities who may not routinely access primary care services, other screening programmes may be acceptable, provided these are supported by the local health services and consideration has been given to follow up, referral and support. Pharmacists considering setting up an early case identification service for diabetes are advised to consult the professional requirements relating to diagnostic testing and health screening as set out in the Code of Ethics1. Further information about screening services within pharmacies please refer to Diabetes UK: Care Recommendations for early identification of diabetes for community pharmacists 2003(27) or the Royal Pharmaceutical Society for Great Britain practice guidance on the care of people with diabetes 2004 (including guidance on early identification).(25) 7. Response to screening results It is important to consider the impact a positive screening result may have on an individual. Diabetes is a chronic condition with potentially disabling outcomes and a high mortality rate. As well as medical considerations, there may also be an impact on lifestyle, including employment and insurance issues. Patients with a family history of the condition may well have had very negative experiences of living with diabetes. Consideration should therefore be given to the provision of emotional and educational support at this stage. a. Screening Test Positive – if the screening test is regarded as positive, the person should be given written details of the nature of the screening procedure and the precise result of the test. He/she should be told that the test has indicated a possible rise in blood glucose which needs further checking and should be reassured as far as possible. The person should be asked not to make any changes in diet or drug therapy but should make a routine appointment with the GP in the two to four weeks following screening (an earlier appointment may be suggested if the person is symptomatic). The GP should thereafter confirm the diagnosis by a formal glucose assay performed by a reputable laboratory or, if this is not possible, should refer the person to a diabetic clinic for further assessment. 1 Code of Ethics and Standards. Medicines, Ethics and Practice: A Guide for Pharmacists. Royal Pharmaceutical Society of Great Britain, July 2001
  • 7. Early identification of people with Type 2 diabetes Page 7 of 10 No therapy should be instigated until a final diagnosis in line with the World Health Organisation's (WHO) criteria(28) has been established. Diagnosis of Diabetes It is important that a screening test for Type 2 diabetes is not seen as being a diagnostic test – no final diagnosis of diabetes (or absence of diabetes) is possible and the person must be referred for appropriate confirmatory testing as necessary.(28) • A diagnosis of diabetes can be confirmed by: • A random venous plasma glucose concentration > 11.1 mmol/l • A fasting venous plasma glucose (FPG) concentration > 7.0 mmol/l (whole blood >6.1) or • A two hour venous plasma glucose concentration > 11.1 mmol/l 2 hours after a 75g anhydrous oral glucose tolerance test In asymptomatic subjects, performing the test on one occasion is not enough to establish the diagnosis (i.e. basis to treat diabetes). This must be confirmed by carrying out at least one further test on a subsequent day. b. Screening Test Negative (with symptoms) – if the screening test is regarded as negative and person has symptoms or signs suggestive of diabetes or its complications he/she should be asked to seek advice from their GP, who should be informed of the screening test result and told that diabetes has not been excluded. c. Screening Test Negative (with no symptoms) - if the person has no symptoms, information, advice and support should be provided to help them change behaviour as appropriate and reduce risk factors. They may not have diabetes currently or raised blood glucose levels, but they will still be at risk of developing diabetes, and other CVD morbidity, in the future. Acknowledgements These care recommendations are made on the basis of consensus amongst healthcare professional and research members of Diabetes UK Professional Advisory Council. With particular thanks to Naveed Sattar, Sally Marshall, Richard Holt, James Walker, Jonathan Richards, Irene Gummerson, Jonathan Richards, Brenda Purnell and Rosie Walker for their advice and support in the development of these recommendations. © Diabetes UK 2006 Appendix 1
  • 8. Early identification of people with Type 2 diabetes Page 8 of 10 Methods of screening for diabetes (3,25,27,29) Data on the performance of some of these tests in the screening context is limited though it is clear that there is no single ideal test for diabetes screening with high sensitivity and specificity and positive predictive value close to 100 per cent. There are few studies comparing different screening tests in the same population and the populations studied are often very different to the UK population. In comparing tests, specificity and sensitivity from published work is quoted and assessments of positive predictive value (PV+) are made on the basis of a one to two per cent prevalence of undiagnosed diabetes. Based on the available information, the proposed screening tests can be placed in a rough ‘order of merit’. The choice of screening methods should be made on the basis of local circumstances such as the availability of staff, methods of follow up etc. It is not recommended that more than one test be performed on each person. 1. Two hour post glucose load blood glucose assay – use of an oral glucose load, usually in the form of a glucose-containing drink, with subsequent measurement of blood glucose is the basis of the oral glucose tolerance test (OGTT) the ‘gold standard’ for assessment of carbohydrate tolerance. While a full supervised OGTT would represent the best possible screening test for diabetes it is not usually practical when large numbers of people are being screened. An unsupervised glucose load test, in which a person consumes 75g of oral glucose in liquid form and has a single blood glucose assay 120 minutes later (as timed by the individual) gives a reasonable approximation to a formal OGTT and is potentially usable on a larger scale. Studies have shown a screening laboratory–measured capillary plasma glucose >8.6 mmol/l to have a sensitivity of 90 per cent, specificity of 93 per cent and PV+ of 18 per cent. A result above 11.1 mmol/l is diagnostic of diabetes. However, results between 7.8 mmol/l and 11.1 mmol/l would indicate the need for further testing because of the risk of Impaired Fasting Glucose and Impaired Glucose Tolerance. 2. Fasting blood glucose – fasting blood glucose is a remarkably constant parameter on a day-to- day basis in both people without diabetes and those with Type 2 diabetes. In a screening context it is a useful single test which will inevitably miss those people with a carbohydrate intolerance whose hyperglycaemia is only manifest after a carbohydrate load. Sensitivity can be improved by lowering the threshold for a ‘positive’ test but this is achieved at the expense of a reduced specificity and PV+. 3. Random blood glucose – screening with this test is not as sensitive or specific as fasting blood glucose [or a 2 hour OGTT] but may be the most practical test. However its sensitivity and specificity of readings that are slightly raised is not good. Very high results are a good
  • 9. Early identification of people with Type 2 diabetes Page 9 of 10 indicator of IFG/IGT, but lower ranges of 6-10 mmol/l may need to be rescreened using a fasting test. 4. Post prandial/post glucose glycosuria – testing for glycosuria is most sensitive following ingestion of food, either a specific glucose load or a normal meal. The technique is limited by variations in the renal threshold for glucose, especially the tendency for the threshold to rise with age and by the sensitivity or the glycosuria detection method, usually a commercial glucose-oxidase based dipstick. These procedures are the recommended screening methods. Method one has the best sensitivity but is the most complex procedure. Method four has the lowest PV+ but is the simplest, while methods two and three lie in the middle in terms of complexity and screening performance. Selection of the best test will depend on local circumstances such as facilities and ease of follow up. Method one, for example may be most appropriate where an individual, perhaps with a family history of diabetes or other risk factor, presents for screening while method three may be the method of choice for screening of a large population (eg a factory or a GP practice population). Selection of the best test will depend on local circumstances such as facilities and ease of follow up. Method one may, for example, be most appropriate where an individual, perhaps with a family history of diabetes or other risk factor, presents for screening while method three may be the method of choice for screening of a large population (eg a factory or a GP practice population). Any screening programme will identify people with IFG or IGT. They should be tested, in line with WHO standards, to rule out a diagnosis of diabetes. This population will need to be provided with lifestyle advice, support and information about healthy eating and physical activity and will need to be screened for diabetes on a three yearly basis. References 1 Department of Health. National Service Framework for Diabetes - England. Standards (2001) and Delivery Strategy (2002). 2 UK Prospective Diabetes Study Group (UKPDS) 'Complications in newly diagnosed type 2 diabetic patients and their association with different clinical and biochemical risk factors.' Diabetes Research. Tivot-Kimpton Publications. 1998. 3 Report of a WHO and IDF meeting Geneva. Screening for Type 2 diabetes. 2003
  • 10. Early identification of people with Type 2 diabetes Page 10 of 10 4 Your local care. Diabetes Services in England. Dr Foster and Diabetes UK 2005 5 Derived from Forouhi etal. Diabetes prevalence in England, 2001 – estimates from an epidemiological model. Diabetic Medicine 2005, 23, 189-197 [Reference states 667,000 for England alone, if this figure is extrapolated pro rata for the rest of the UK, then the undiagnosed will be closer to 750,000] 6 Further information is available http://www.screening.nhs.uk/diabetes/home.htm 7 Simmons, D et al. 'The Coventry Diabetes Study: prevalence of diabetes and impaired glucose tolerance in Europids and Asians.' Quarterly Journal of Medicine 1991, New Series 81(no. 296): 1021-1030. 8 Greenhalgh, PM. 'Diabetes in British South Asians: nature, nurture and culture.' Diabetic Medicine. 14: 10-18. 9 Williams G & Pickup JC (2004) Handbook of diabetes Oxford: Blackwell 10 Tucker, KL et al Type 2 Diabetes is prevalent and poorly controlled among Hispanic elders of Caribbean origin American Journal of Public Health 2000 90 pp1288-1293 11 Morricone L et al The role of central fat distribution in coronary artery disease in obesity: comparison of nondiabetic obese, diabetic obese and normal weight subjects International Journal of Obesity Related Metabolism Disorders 1999 23 pp1129-1135 12 Carey, DG et al Abdominal fat and insulin resistance in normal and overweight women: direct measurements reveal a strong relationship in subjects at both low and high risk of NIDDM. Diabetes Care 1996 45 pp633-638 13 Warne, DK Comparison of body size measurements as predictors of NIDMM in Pima Indians. Diabetes Care 1995 18 pp435-439 14 Wei et al Waist circumference as the best predictor of non-insulin dependent diabetes mellitus (NIDDM) compared to body mass index., waist hip ratio and other anthropometric measurements in Mexican Americans- a 7 year prospective study. Obesity Research 1997 5 pp16-23 15 Wat, NMS et al Central obesity predicts the worsening of glycaemia is Southern Chinese. International Journal of Obesity 2001 25 pp1789-93 16 Coronary Heart Disease NSF: Chapter Two: Preventing coronary heart disease in high risk groups. Department of Health. 2000. 17 Care Recommendation: Recommendations for the management of pregnant women with diabetes (including Gestational diabetes. Diabetes UK June 2005. 18 Kar PS, Cummings MH. Polycystic ovary syndrome. Practical Diabetes International. September 2005. Vol. 22 No.7 19 Shaw JE, Zimmet PZ, de Courten M, Dowse GK, Gareeboo H, Hemraj F et al. Impaired Fasting Glycemia or Impaired Glucose Tolernace: What best predicts future diabetes in Mauritius? A view of the new ADA recommendations. Diabetes Care 1999; 22 (3): 399 20 Alberti KGMM. The clinical implications of Impaired Glucose Tolerance. Diabet Med 1996; 13: 927-37 21 Holt R, Peveler R. Hyperglycaemia and diabetes in patients with serious mental illnesses. A quick reference guide.2004 22 ‘Schizophrenia and Diabetes 2003’. Expert of Consensus Meeting. BRJ Psychiatry 2004 23 Schizophrenia. Core interventions in the treatment and management of schizophrenia in primary and secondary care. Clinical Guideline CG001. December 2002 24 Kametani T. Koshida H. Nagaoka T. Miyakoshi H., Hypertriglyceridemia is an independent risk factor for development of impaired fasting glucose and diabetes mellitus: A 9-year longitudinal study in Japanese. Internal Medicine. Vol. 41(7)(pp 516-521), 2002. 25 Royal Pharmaceutical Society of Great Britain. Practice guidance on the care of people with diabetes (incorporating ‘Early Identification’ guidance). November 2004. http://www.rpsgb.org.uk/members/practice/practguid.html 26 Recommendations for the provision of services in primary care for people with diabetes. Diabetes UK. 2005 27 Care recommendation: early Identification of diabetes for community pharmacists. Diabetes UK 2003 28 Definition, diagnosis and classification of diabetes mellitus and its complications. Report of a WHO Consultation. Part 1: Diagnosis and classification of diabetes mellitus. 1999. Geneva: World Health Organization. WHO/NCD/NCS/99.2 (http://www.who.int) (visit our website (http://www.diabetes.org.uk) to download a summary) 29 Population screening for diabetes mellitus. Dr K Paterson MB FRCP, Joint Honorary Secretary, Professional Advisory Committee of BDA, Chairman, Population Screening for Diabetes Working Party. British Diabetic Association 1992

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