EDITORIAL

Screening For Curly Two Disease: ATransatlantic PerspectiveLast month, the American Diabetes Association published 1980 criteria. The ADA set out to define a classification

of diabetes, independent of treatment modality, whichthe report of its Expert Committee on The Diagnosis andClassification of Diabetes Mellitus (1). A month earlier, would provide a comprehensive definition of types of

diabetes, be globally acceptable both in terms ofin June, the recommendations of that committee hadbeen made public in an “Information Session” at the rationality and practicality, adequately identify people at

risk of disease and disability and provide a scientific57th Annual Meeting and Scientific Sessions of the ADA,in a hot and humid Boston. A past president of the basis for assigning patients to research protocols and

treatment therapies.ADA, Dr James Gavin III, presented and explained theconclusions of the Committee, which he had chaired, With these aims in mind, the ADA collected its experts

in 1995. They reviewed published and unpublished data,and George Alberti put the ADA recommendations intoa global perspective. They were an inspired team – Dr met in person and over the ether on several occasions

and sent a draft report to the American DiabetesGavin warmed and relaxed the atmosphere in the super-cooled, air-conditioned ballroom almost immediately community before refining and revising their work into

the consensus document that appeared last month.by his masterful management of both its defectiveamplification systems and his tense and over-capacity The new diagnostic criteria are set out in Table One. In

the absence of urgency and a grossly elevated circulatingaudience; Professor Alberti mined a vein of humour thatcrossed the Atlantic and even passed beneath the English glucose level, the ADA are recommending the fasting

plasma glucose concentration as the test of choice –Channel. When they finished with time to spare and,ignoring instructions, invited discussion for the floor, taken after an 8-hour fast and repeated on two separate

days. The oral glucose tolerance test has lost out becausethey turned the Information Session into a good-humouredand uninhibited workshop with a skill that the moderators of its expense, inconvenience and lack of reproducibility.

Glycosylated haemoglobin was apparently consideredof the much smaller, official workshops of the Conferencecould only envy. on an alternative but is also expensive and not standard-

ised. Even if a current Pan-American assay standardisationGeorge Alberti had been one of two non-Americanmembers of the ADA expert committee and is chairman is successful (and this journal has recently reported

British efforts in this field), the vehement advocate ofof its counterpart in the rest of the world – the morecircumspectly named WHO consultation group – whose the HbA1c as a replacement for the fasting plasma

glucose an the diagnostic test at the June meetingdocument on the same issues is due out later this year.With this expected so shortly, you may question the sounded dangerously parochial. The 75gm oral glucose

tolerance test remains available and the two-hour postneed to debate the American report now. Many of youwill have seen the US recommendations already and plasma glucose value is unchanged. However, the

emphasis on the fasting plasma test has led to thesome may have put them to one side in the knowledgethat the Americans have done their own thing in diabetes introduction of a new category to join impaired glucose

tolerance – the cumbersomely named impair fasting glu-diagnosis before and why should we worry about theiradvice now? However, the WHO review was prompted cose or IFG.

The major change is the lowering of the diagnosticby the same factors that motivated the ADA and the twoorganisations have worked closely together in the hope fasting plasma glucose concentration. The effects of this

are not, as some suggested, to increase the number ofof achieving a global consensus (at least in this). Althoughthe initial WHO report will be a consultation document, people with diabetes (by 2 million Americans, apparently)

but to identify more of those at risk of diabeticit is informed by the same data and it is almost certain,with a few exceptions, that its recommendations will be complications at an earlier stage. This is a long overdue

improvement. Few of us can doubt that people withthe same as those of the ADA. We must certainly hopeso! It therefore seems opportune to study the ADA fasting plasma glucose levels of 7.2 mmol l-l were not

“normal” in the past. Dr David Nathan′s argument,criteria and understand their rationale as the WHOconsultation group advises. expressed in the New York Times the next day, that

diagnosing healthy people may be dangerous, is notWhy did we need to review the diagnostic criteriaand classification system for diabetes mellitus for the compatible with his previous vigorously expressed and

evidence-based view that maximal lowering of glycatedMillennium? As Dr Gavin explained, our increasingknowledge of the pathogenesis of diabetes, the accumu- haemoglobin to levels well below those require for

symptom control, should be the goal of good diabeteslating data on risk for diabetes complications and thecontinued confusion between insulin dependency and therapy. The new level has been chosen from such

evidence as is available to link fasting plasma glucoseinsulin requirement mandated a review of the 1979 and

635CCC 0742–3071/97/080635–02$17.50 1997 by John Wiley & Sons, Ltd. DIABETIC MEDICINE, 1997; 14: 635–636

EDITORIALlevels with risk of complications – mostly, and sadly desirable, end. In one area however, America will

continue to differ from the WHO – the diagnostic criteriaretinopathy. Published data link the new fasting plasmafor gestational diabetes remain unchanged.glucose with the 2 hour post glucose load valuesYour editor was enthusiastic about the changes rec-previously associated with sudden rise in risk of retino-ommended. She would particularly like to draw herpathy in Pina Indians, Pacific Islanders and 40 to 74readers′ attention to one final, minor but significantyear old Americans and directly with approximatepoint, beautifully described by Dr Gavin, in whichthresholds for retinopathy in Egyptians as well. It is aDiabetic Medicine has pre-empted the ADA by severalpity that good data do not exist to link fasting (or undeedyears. In order to avoid confusion in the lay public,two-hour) plasma glucose concentrations with risk ofType I and Type II diabetes mellitus have vanishedmacrovascular disease but no doubt such data will come.forever. As Dr Gavin said, to avoid misreading the latterA much more radical recommendation from the Commit-as an eleventh type of diabetes and questioning whattee than a mere, evidence-based 0.8mmol l-l reductionbecame of the missing nine, Roman numbers have beenin diagnostic plasma glucose concentration concernseliminated, and Arabic numerals made the rule. Welcomescreening. Armed with the new, simpler – and cheaper –to screening for curly two disease!diagnostic tool, Dr Gavin told us the ADA now rec-

ommends screening for diabetes all populations atincreased risk for Type 2 disease. As the risk factors Stephanie A. Amiel BSc, MD, FRCPinclude amongst the environmental factors age over RD Lawrence Professor of Diabetic Medicine45 years, this is effectively population screening. The King′s College, LONDONrecommendation is for three yearly screening, if resultsare normal, with screening of younger people at increased Table 1. Diagnostic criteria for diabetes mellitus and other degrees

of glucose intolerancegenetic (positive family history; Native American, His-Plasma glucose mmol. L-lpanic, Asian and African American) or environmental

Fasting 2h-post 75g(obese, hypertensive, dyslipidaemic, previously ges-glucose load

tational diabetic or impaired glucose metabolism) risk. Diabetes $7.0 and/or 11.1It is this that will increase the number of overtly diabetic IGT ,7.0 7.8–11.0

Impaired fasting glucose 6.1–6.9 –Americans. Given my previous argument, I cannotcomplain of this, although I do think, its cost effectiveness,

In the absence of symptoms the diagnosis must be confirmed by aas with any screening test, needs to be carefully monitored second diagnostic value on a separate day.and reviewed.

Table 2. Classification of diabetes mellitusHaving diagnosed diabetic mellitus, what of its classi-fication (Table Two)? In its attempt to base this on

Type 1 diabetes mellitusaetiology, the US may at first glance be a little ahead of ß cell destruction, usually leading to absolute insulin deficiency.current knowledge or availability (or even desirability) * (A) immune mediated

* (B) idiopathicof diagnostic testing. I understand that an initial proposal,to create a category of auto-immune diabetes based on

Type 2 diabetes mellitusauto-antibody screening, found support in high-tech,ranging from predominantly insulin resistant with relative insulin

high-cost Occidentialism but such a category would deficiency to predominantly an insulin secretory defect with insu-have been unusable in most areas of the world and the lin resistance.categorisation of Type 1 diabetes mellitus will remain,

Other specific typesfor most of us, a question of clinical recognition of* genetic defects in ß cell function

insulin deficiency and ketosis prone disease. Allocation * genetic defects in insulin actionto Type 1A or 1B will be a matter for choice based on * disease of the exocrine pancreas

* endocrinopathicsclinical or academic need to know and availability of* drug or chemical induceddiagnostic tests. It seems likely to this reviewer that* infection inducedcategory B patients may dwindle as new islet antigens* uncommon forms of immune related diabetes

and autoantibodies are uncovered, although non-immune * other genetic syndromesaetiology remains likely in at least some of the 80% of

Gestational diabetes mellitusAfricans for example with antibody negative clinicalType 1 disease. It is incidentally important to realise thatthe committee viewed each category of diabetes as acontinuum with people moving from normoglycaemia,

Referencesthrough IGT and IFG, to diabetes mellitus which doesnot require insulin, diabetes mellitus requiring insulin

1. Expert Committee on the Diagnosis and Classification offor control and exclusively. Diabetes Mellitus. Report of the Expert Committee on theA meeting of minds was clear in the ADA conference Diagnosis and Classification of Diabetes Mellitus. Diabetes

Care 1997; 20.and consensus with the WHO seems a likely, and hugely

636 EDITORIAL