The glycohaemoglobin assay as a screening test for diabetes mellitus: the Islington Diabetes Survey

Vitamin D Supplementation and Prevention of Type 2 Diabetes

BACKGROUND

Observational studies support an association between a low blood 25-hydroxyvitamin D level and the risk of type 2 diabetes. However, whether vitamin D supplementation lowers the risk of diabetes is unknown.

METHODS

We randomly assigned adults who met at least two of three glycemic criteria for prediabetes (fasting plasma glucose level, 100 to 125 mg per deciliter; plasma glucose level 2 hours after a 75-g oral glucose load, 140 to 199 mg per deciliter; and glycated hemoglobin level, 5.7 to 6.4%) and no diagnostic criteria for diabetes to receive 4000 IU per day of vitamin D₃ or placebo, regardless of the baseline serum 25-hydroxyvitamin D level. The primary outcome in this time-to-event analysis was new-onset diabetes, and the trial design was event-driven, with a target number of diabetes events of 508.

RESULTS

A total of 2423 participants underwent randomization (1211 to the vitamin D group and 1212 to the placebo group). By month 24, the mean serum 25-hydroxyvitamin D level in the vitamin D group was 54.3 ng per milliliter (from 27.7 ng per milliliter at baseline), as compared with 28.8 ng per milliliter in the placebo group (from 28.2 ng per milliliter at baseline). After a median follow-up of 2.5 years, the primary outcome of diabetes occurred in 293 participants in the vitamin D group and 323 in the placebo group (9.39 and 10.66 events per 100 person-years, respectively). The hazard ratio for vitamin D as compared with placebo was 0.88 (95% confidence interval, 0.75 to 1.04; P = 0.12). The incidence of adverse events did not differ significantly between the two groups.

CONCLUSIONS

Among persons at high risk for type 2 diabetes not selected for vitamin D insufficiency, vitamin D₃ supplementation at a dose of 4000 IU per day did not result in a significantly lower risk of diabetes than placebo. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; D2d ClinicalTrials.gov number, NCT01942694.).

A1C level and future risk of diabetes: a systematic review

We examined ranges of A1C useful for identifying persons at high risk for diabetes prior to preventive intervention by conducting a systematic review. From 16 included studies, we found that annualized diabetes incidence ranged from 0.1% at A1C <5.0% to 54.1% at A1C >or=6.1%. Findings from 7 studies that examined incident diabetes across a broad range of A1C categories showed 1) risk of incident diabetes increased steeply with A1C across the range of 5.0 to 6.5%; 2) the A1C range of 6.0 to 6.5% was associated with a highly increased risk of incident diabetes, 25 to 50% incidence over 5 years; 3) the A1C range of 5.5 to 6.0% was associated with a moderately increased relative risk, 9 to 25% incidence over 5 years; and 4) the A1C range of 5.0 to 5.5% was associated with an increased incidence relative to those with A1C <5%, but the absolute incidence of diabetes was less than 9% over 5 years. Our systematic review demonstrated that A1C values between 5.5 and 6.5% were associated with a substantially increased risk for developing diabetes.

A new look at screening and diagnosing diabetes mellitus

OBJECTIVE

Diabetes is underdiagnosed. About one third of people with diabetes do not know they have it, and the average lag between onset and diagnosis is 7 yr. This report reconsiders the criteria for diagnosing diabetes and recommends screening criteria to make case finding easier for clinicians and patients.

PARTICIPANTS

R.M.B. invited experts in the area of diagnosis, monitoring, and management of diabetes to form a panel to review the literature and develop consensus regarding the screening and diagnosis of diabetes with particular reference to the use of hemoglobin A1c (HbA1c). Participants met in open session and by E-mail thereafter. Metrika, Inc. sponsored the meeting.

EVIDENCE

A literature search was performed using standard search engines.

CONSENSUS PROCESS

The panel heard each member's discussion of the issues, reviewing evidence prior to drafting conclusions. Principal conclusions were agreed on, and then specific cut points were discussed in an iterative consensus process.

CONCLUSIONS

The main factors in support of using HbA1c as a screening and diagnostic test include: 1) HbA1c does not require patients to be fasting; 2) HbA1c reflects longer-term glycemia than does plasma glucose; 3) HbA1c laboratory methods are now well standardized and reliable; and 4) errors caused by nonglycemic factors affecting HbA1c such as hemoglobinopathies are infrequent and can be minimized by confirming the diagnosis of diabetes with a plasma glucose (PG)-specific test. Specific recommendations include: 1) screening standards should be established that prompt further testing and closer follow-up, including fasting PG of 100 mg/dl or greater, random PG of 130 mg/dl or greater, or HbA1c greater than 6.0%; 2) HbA1c of 6.5-6.9% or greater, confirmed by a PG-specific test (fasting plasma glucose or oral glucose tolerance test), should establish the diagnosis of diabetes; and 3) HbA1c of 7% or greater, confirmed by another HbA1c- or a PG-specific test (fasting plasma glucose or oral glucose tolerance test) should establish the diagnosis of diabetes. The recommendations are offered for consideration of the clinical community and interested associations and societies.

Is the measurement of glycated hemoglobin A1c alone an efficient screening test for undiagnosed diabetes? Japan National Diabetes Survey

The aim of the study was to assess the screening test properties of HbA1c for undiagnosed diabetes (DM) according to the 1999-WHO criteria and its relevance of the Japan National Diabetes Survey Cut-off points for possible and probable DM: HbA1c >or=5.6 and 6.1%. Screening properties of HbA1c predicting undiagnosed DM was examined and compared with that of fasting plasma glucose (FPG) in 1904 Funagata-town inhabitants aged 35-89 years old. The prevalence of previous DM, undiagnosed DM, and impaired glucose regulation (IGR) were 5.5, 6.0, and 18.6%, while the prevalence of probable and possible DM were 7.7 and 5.4%. The area under the receiver operating characteristic curve for undiagnosed DM was similar between HbA1c (0.856 [95% CI: 0.812-0.899]) and FPG (0.902 [0.869-0.936]). HbA1c of 5.6% gave a sensitivity of 56.5%, a specificity of 95.1%, positive and negative predictive values of 44.2 and 97.0%, and a proportion of people above the cut-off point of 8.2%. True positive tests were significantly higher with mean levels of BMI, fasting, and 2-h plasma glucose, and HbA1c, but lower with mean levels of high-density-lipoprotein cholesterol than in false negative tests. The measurement of HbA1c alone may be efficient to screen undiagnosed DM and the cut-off point of 5.6% might be proper with respect to screening tests properties for undiagnosed DM, and prediction of vascular complications in Japan.

Comparison of coronary heart disease risk factors in autopsied young adults from the PDAY Study with living young adults from the CARDIA study

BACKGROUND

Disease is sometimes best studied by examination of tissue obtained from autopsied individuals. Results derived from autopsied persons are considered biased because many factors influence the decision to perform an autopsy, and variables measured postmortem may be affected by changes immediately prior to death and emergency medical treatment.

METHODS

The Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study measured coronary heart disease risk factors postmortem in autopsied young adults 23-34 years of age dying from external causes (accidents, homicides, suicides). The Coronary Artery Risk Development in Young Adults (CARDIA) study measured risk factors in living subjects of similar ages.

RESULTS

Within sex, race, and age groups, the differences in body mass index between PDAY and CARDIA were significant but small. The prevalences of hyperglycemia/diabetes within sex, race, and age groups were similar in PDAY and CARDIA; overall, blacks in PDAY, but not in CARDIA, had a higher prevalence than whites. Serum lipoprotein concentrations were slightly and significantly higher and significantly more variable in PDAY subjects than in CARDIA subjects; the greater variability was interpreted as due primarily to emergency medical treatment. Prevalences of smoking and hypertension were substantially higher in PDAY subjects.

CONCLUSIONS

Although there were statistically significant differences, the overall similarity of the risk factors in the two studies supports the validity of investigating associations of risk factors measured postmortem with anatomically determined arterial lesions in autopsied young adults dying from external causes. The greater variability in postmortem serum measurements attenuates but does not obscure associations.

Combined Use of Fasting Plasma Glucose and Glycated Hemoglobin A1c in a Stepwise Fashion to Detect Undiagnosed Diabetes Mellitus

Type 2 diabetes mellitus (DM) is a common and serious condition related with considerable morbidity. Screening for DM is one strategy for reducing this burden. In Japan National Diabetes Screening Program (JNDSP) guideline, the combined use of fasting plasma glucose (FPG) and glycated hemoglobin A1c (HbA1c) in a stepwise fashion has been recommended to identify the group of people needing life-style counseling or medical care. However, the efficacy of this program has not been fully evaluated, as an oral glucose tolerance test (OGTT) is not mandatory in the guideline. The aim of this study was to assess the validity of the screening test scenario, in which an OGTT would be applied to people needing life-style counseling or medical care on this guideline: FPG 110-125 mg/dl and HbA1c over 5.5%. Subjects were 1,726 inhabitants without a previous history of DM in the Funagata study, which is a population-based survey conducted in Yamagata prefecture to clarify the risk factors, related conditions, and consequences of DM. DM was diagnosed according to the 1999 World Health Organization criteria. The prevalence of undiagnosed DM was 6.6%. The tested screening scenario gave a sensitivity of 55.3%, a specificity of 98.4%, a positive predictive value of 70.8%, and a negative predictive value of 96.9% for undiagnosed DM. In conclusion, the screening test scenario, in which an OGTT would be followed by the combined use of FPG and HbA1c in a stepwise fashion according to the JNDSP guideline, was not effective in identifying people with undiagnosed DM.

Screening for diabetes in general practice

The prevalence of type 2 diabetes is rising rapidly worldwide. Evidence suggests that between one third and one half of cases are undiagnosed and patients may have preclinical disease for as long as 12 years. At diagnosis, 50% of patients have microvascular complications (retinopathy, neuropathy, or nephropathy) and patients have twice the risk of macrovascular disease compared to the background population. Screening for type 2 diabetes would allow earlier recognition of cases, with the potential to intervene earlier in the disease course, but whether this would result in improved long-term outcomes is unknown. The debate continues about who should be considered for screening, how we should screen, and whether we should screen for diabetes at all. The authors review the evidence, particularly in light of the recent position statement on diabetes screening published by the American Diabetes Association. If we do start screening for diabetes, one of the major challenges ahead is to ensure resources are in place to allow optimization of treatment for the increasing number of patients. This is important both in those found to have diabetes and in those with lesser degrees of glucose intolerance who are at high risk of developing diabetes and are at increased risk of macrovascular disease.

Performance of recommended screening tests for undiagnosed diabetes and dysglycemia

OBJECTIVE

To evaluate the performance, in settings typical of opportunistic and community screening programs, of screening tests currently recommended by the American Diabetes Association (ADA) for detecting undiagnosed diabetes.

RESEARCH DESIGN AND METHODS

Volunteers aged > or =20 years without previously diagnosed diabetes (n = 1,471) completed a brief questionnaire and underwent recording of postprandial time and measurement of capillary blood glucose (CBG) with a portable sensor. Participants subsequently underwent a 75-g oral glucose tolerance test; fasting serum glucose (FSG) and 2-h postload serum glucose (2-h SG) concentrations were measured. The screening tests we studied included the ADA risk assessment questionnaire, the recommended CBG cut point of 140 mg/dl, and an alternative CBG cut point of 120 mg/dl. Each screening test was evaluated against several diagnostic criteria for diabetes (FSG > or =126 mg/dl, 2-h SG > or =200 mg/dl, or either) and dysglycemia (FSG > or =110 mg/dl, 2-h SG > or =140 mg/dl, or either).

RESULTS

Among all participants, 10.7% had undiagnosed diabetes (FSG > or =126 or 2-h SG > or =200 mg/dl), 52.1% had a positive result on the questionnaire, 9.5% had CBG > or =140 mg/dl, and 18.4% had CBG > or =120 mg/dl. The questionnaire was 72-78% sensitive and 50-51% specific for the three diabetes diagnostic criteria; CBG > or =140 mg/dl was 56-65% sensitive and 95-96% specific, and CBG > or =120 mg/dl was 75-84% sensitive and 86-90% specific. CBG > or =120 mg/dl was 44-62% sensitive and 89-90% specific for dysglycemia.

CONCLUSIONS

Low specificity may limit the usefulness of the ADA questionnaire. Lowering the cut point for a casual CBG test (e.g., to 120 mg/dl) may improve sensitivity and still provide adequate specificity.

Diabetes risk score: towards earlier detection of type 2 diabetes in general practice

BACKGROUND

Type 2 diabetes is common, costly and often goes unrecognised for many years. When patients are diagnosed, the majority exhibit associated tissue damage or established cardiovascular risk. Evidence is accumulating that earlier detection and management of diabetes and related metabolic abnormalities may be beneficial. We aimed to develop and evaluate a score based on routinely collected information to identify people at risk of having undetected diabetes.

METHODS

A population-based sample of 1077 people, aged 40 to 64 years, without known diabetes, from a single Cambridgeshire general practice, underwent clinical assessment including an oral glucose tolerance test. In a separate 12-month study, 41 practices in southern England reported clinical details of patients aged 40 to 64 years with newly diagnosed Type 2 diabetes. A notional population was created by random selection and pooling of half of each dataset. Data were entered into a regression model to produce a formula predicting the risk of diabetes. The performance of this risk score in detecting diabetes was tested in an independent, randomly selected, population-based sample.

RESULTS

Age, gender, body mass index, steroid and antihypertensive medication, family and smoking history contributed to the score. In the test population at 72% specificity, the sensitivity of the score was 77% and likelihood ratio 2.76. The area under the receiver-operating characteristic curve was 80%.

CONCLUSIONS

A simple score, using only data that are routinely collected in general practice, can help identify those at risk of diabetes. This score could contribute to efficient earlier detection through case-finding or targeted screening.

Investigation of the mechanism underlying the variability of glycated haemoglobin in non-diabetic subjects not related to glycaemia

The Islington Diabetes Survey identified two groups of non-diabetic individuals, low and high glycators, who remained consistently classified 4.4 +/- 0.2 years after the original study. To investigate the mechanism for this grouping, 12 original subjects, 5 with low and 7 with high levels of glycated haemoglobin relative to their 2 h blood glucose, were studied. Glycated albumin and fructosamine measurements gave comparable classifications, with three individuals being misclassified for each measurement; in addition glycated albumin was positively correlated with mean blood-glucose concentration (r = 0.53; P < 0.05). Fasting plasma glucose concentration was greater than the intra-erythrocyte concentration (P < 0.05), but their ratio was reduced in low compared to high glycators (0.77 +/- 0.12 and 0.94 +/- 0.13, P < 0.0001). No differences between groups were found for plasma insulin, urea or non-esterified fatty acids; plasma or intra-erythrocyte inorganic phosphate or vitamin C; nor plasma, erythrocyte or urinary total amino acids. Erythrocyte 2,3-diphosphoglycerate, a catalyst of glycation, was elevated in high compared to low glycators (5.61 +/- 0.26 and 4.81 +/- 0.24 mmol/l, P < 0.001). Mean centile glycated haemoglobin was positively correlated with intra-erythrocyte pH (r = 0.55; P < 0.05) and negatively with plasma total amino acids (r = -0.57, P < 0.05). These data indicate that the intra-erythrocyte environment of high glycators favours glycation of haemoglobin. This could have important consequences for diabetic patients in terms of monitoring their glycaemic control and in the progression of those complications related to non-enzymic glycation of intracellular proteins.

Tracking of glycated hemoglobin in the original cohort of the Framingham Heart Study

Glycated hemoglobin measures average blood glucose over the preceding 2 to 3 months. The authors examined the tracking of the major glycated hemoglobin A1c (HbA1c), over a period of 4 to 6 years. Two HbA1c measurements were obtained between 1986 and 1993 from 639 elderly, presumptively nondiabetic members of the original cohort of the Framingham Heart Study, Framingham, Massachusetts. Mean +/- standard deviation (SD) baseline and follow-up HbA1c were 5.43% +/- 0.7 and 5.71% +/- 0.9, respectively. Intraclass correlation of 0.59 between baseline and follow-up measurements indicated good reliability of a single HbA1c measurement. Ninety-one percent of follow-up measurements were within +/- 20% of baseline value; HbA1c values tended to move 15% closer to the baseline mean over time. There was a modest tendency for HbA1c values to increase with time; the mean difference between measurements was 0.28% +/- 0.7 SD (p < 0.0001). Change in HbA1c was positively associated with age and body mass index at baseline examination, and negatively associated with cigarette smoking, even after controlling for age and body mass index. These effects were very small, however. We conclude that glycated hemoglobin reliably categorizes the glucose control of nondiabetic subjects over a period of 4 to 6 years, confirming its value as an epidemiological measure.

High glycosylated hemoglobin levels increase the risk of progression to diabetes mellitus in subjects with glucose intolerance

The relationships between HbA1c level and oral glucose tolerance test (OGTT) at the initial visit and the incidence of diabetes after 5 years of follow-up were investigated in 819 subjects participating in a general health examination. The 100 g OGTT was performed. In order to use WHO criteria, the blood glucose levels of 100 g OGTT corresponding to those of 75 g OGTT were adopted according to the recommendations of the Japan Diabetes Society. Subjects other than diabetic type and IGT (impaired glucose tolerance) were divided into a normal group (fasting blood glucose < 100 mg/dl, 1-h blood glucose < 160 mg/dl, a 2-h blood glucose < 120 mg/dl) and a borderline group (the remaining subjects). In IGT, the incidence of diabetes in the low- (< or = 6.3%), intermediate- (6.4-6.7%) and high-HbA1c (> of = 6.8%) groups were 10.4%, 23.1% and 52.5%, respectively (high vs intermediate and low, P < 0.001; intermediate vs low, P < 0.05). In the borderline group, the incidence were 2.8%, 14.3% and 28.6%, respectively (high and intermediate vs low, P < 0.001). The results showed that the combination of HbA1c level and OGTT enables more precise prediction of progression to NIDDM in subjects with glucose intolerance.

Relation of glycohemoglobin and adiposity to atherosclerosis in youth. Pathobiological Determinants of Atherosclerosis in Youth (PDAY) Research Group

In a cooperative multicenter study (Pathobiological Determinants of Atherosclerosis in Youth, PDAY) of 1532 young persons 15 through 34 years of age who died of external causes and were autopsied in medical examiners' laboratories, we quantified atherosclerosis of the aorta and the right coronary artery. We analyzed postmortem blood cells for glycohemoglobin and postmortem serum for lipoprotein cholesterol and thiocyanate (as an indicator for smoking). We measured the thickness of the panniculus adiposus and the body mass index (weight per height squared) as indicators of adiposity. Glycohemoglobin levels exceeding 8% were associated with substantially more extensive fatty streaks and raised lesions in the right coronary artery in persons more than 25 years of age and with more extensive raised lesions in the aorta in persons more than 30 years of age. Both thickness of the panniculus adiposus and body mass index were associated with more extensive fatty streaks and raised lesions in the right coronary artery. The associations of atherosclerotic lesions with glycohemoglobin and adiposity were not explained by a less favorable lipoprotein profile or smoking. The results show that atherosclerosis in young adults is associated with the prediabetic or early diabetic state, as indicated by elevated glycohemoglobin levels, and with obesity.

Random blood glucose as a screening test for diabetes in a biethnic population

Screening asymptomatic subjects for diabetes is often undertaken using a random capillary whole blood sample for glucose estimation. The test characteristics of this method for screening were assessed using a glucose oxidase method among 3425 Europeans and 3469 South Asians who gave such a sample during the Coventry Diabetes Study, a house-to-house diabetes prevalence study. Glucose tolerance test were performed on those with a high blood glucose and 10% of others. Previously undiagnosed diabetes was found in 73 Europeans and 110 South Asians. If the random glucose was > or = 7.0 mmol l-1, 8.0% of Europeans and 6.7% of South Asians would need a further diagnostic test and the sensitivity of this cut-off was 51.7 (95.0% CI: 43.5-59.9)% in Europeans and 68.4 (60.6-76.2)% in South Asians. Sensitivity was increased in South Asians but not Europeans by defining the time since last meal (South Asians < 2 h: 83.9 (72.3-92.0)%; > or = 2 h: 54.9 (42.7-66.8)%). Sensitivity was poorest among Europeans aged > or = 65 years (40-64 years 69.0 (49.2-84.7)%, > or = 65 years 49.4 (38.2-60.6)%). Screening asymptomatic individuals using an isolated capillary random whole blood glucose measure is a poor test for diabetes, although slight improvement can be obtained among South Asians by testing within 2 h of a meal.

Effect of advertising on awareness of symptoms of diabetes among the general public: the British Diabetic Association Study

OBJECTIVE

To determine the impact of posters advertising symptoms of diabetes on public knowledge of these symptoms.

DESIGN

Structured street interviews of members of the general public before, at the end of, and 10 weeks after a campaign advertising the main symptoms of diabetes.

SETTING

Basingstoke and Wolverhampton.

SUBJECTS

Three samples of 1000 members of the general public were interviewed. Samples were selected randomly but stratified to match the local population's age (20-75), sex, social class, and racial characteristics.

MAIN OUTCOME MEASURES

Knowledge of symptoms of diabetes; perceived seriousness of diabetes; and induction of anxiety about symptoms in the target population.

RESULTS

Advertising significantly raised knowledge (without prompting) of symptoms: thirst, 245 before v 411 at end of campaign (P < 0.0001) v 341 after (P = 0.0012 v before); polyuria, 72 v 101 (P = 0.0211) v 92 (P = 0.5169); lethargy, 180 v 373 (P < 0.0001) v 298 (P < 0.0001); knowledge of weight loss and visual disturbance was unaffected. The number of subjects lacking knowledge of any symptoms was reduced from 550 to 388 (P < 0.0001). The perceived seriousness of diabetes was unaffected (mean 7.6 in each phase on a scale of 1 (not) to 10 (very). Before advertising, 449 (45%) claimed to have one or more symptoms of diabetes, but this number fell at the end of the campaign (403; P = 0.0419) and 10 weeks afterwards (278; P < 0.0001).

CONCLUSIONS

An advertising campaign raised public knowledge of diabetes symptoms without inducing fear of diabetes or anxiety about symptoms. Its potential for achieving earlier detection of non-insulin dependent diabetes should be evaluated.

Serum fructosamine as a screening test for diabetes in the elderly: a pilot study

OBJECTIVE

To determine the value of serum glycated protein, measured as serum fructosamine, as a screening test for diabetes in the elderly.

DESIGN

Cross-sectional pilot study.

SETTING

Ambulatory research clinic in university setting.

PATIENTS

One hundred fifty-seven consecutive community-dwelling participants in the Cardiovascular Health Study, average age 71.8 + 5 (mean +/- SD, range 65-88 years).

MEASUREMENTS

Serum fructosamine levels (first and second generation assay) were obtained. All subjects who did not have a diagnosis of diabetes were given a 75-g glucose tolerance test (GTT).

RESULTS

Twenty-six subjects (17%) (10 previously diagnosed, 16 undiagnosed and asymptomatic) had diabetes mellitus, and 38 subjects (24%) had impaired glucose tolerance by history or by the GTT (WHO criteria). Only the 16 asymptomatic diabetics were included in the analysis for the pilot study. There was a significant difference in the fasting fructosamine level between non-diabetics and asymptomatic diabetics for the first generation (2.06 +/- .21 vs 2.53 +/- .49 mMol/L, P < 0.0015) and second generation assay (221 +/- 27 vs 269 +/- 48 mMol/L, P < 0.0012). Receiver operator curves were constructed to evaluate the test characteristics of serum fructosamine. Using a point of > or = 2.3 mMol/L for the first-generation assay, the sensitivity to detect asymptomatic diabetes was 75%, specificity 83%, and positive predictive value 35%. To detect both diabetes and impaired glucose tolerance using a cutpoint of > or = 2.3 mMol/L, the sensitivity was 24%, specificity 95%, and positive predictive value 68%. Employing a cut point of 250 muMol/L for the second generation assay, the sensitivity to detect diabetes was 81%, specificity 87%, and positive predictive value 43%. However, to detect diabetes and glucose intolerance using the second generation assay, the sensitivity was 39% and specificity was 86%.

CONCLUSION

This study demonstrated that a single measurement of either first or second generation fructosamine showed promise as a screening test for diabetes, but not impaired glucose tolerance, in older people.

A model for early diagnosis of type 2 diabetes mellitus in primary health care

The aim of the study was to determine the feasibility of conducting a case-finding programme for Type 2 diabetes mellitus in primary health care and to see whether random urinary glucose or random capillary blood glucose testing is the most suitable instrument for the early detection of Type 2 diabetes. Residents in the community of Låxa aged 35-64 years were subjected to testing during 1983-1987; those aged 65-79 were included from July 1985 and onwards. The urinary glucose testing was considered positive if a urinary dipstick was not unequivocally negative. The random blood glucose test was regarded as positive when > or = 8.0 mmol l-1. A diagnosis of Type 2 diabetes made within a follow-up period of 3 years from the initial examination was regarded as a positive outcome. Random blood glucose testing was performed on 3268 persons which was close to 85% of the eligible population. Urinary glucose tests were missing in 67 subjects. The random blood glucose test was positive in 220 persons and the urinalysis in 42 persons. A total of 234 individuals had a positive test, out of which 66 new diabetic cases were found. Sixty-four of these were detected by the random blood glucose testing and 20 by the urinalysis. The sensitivity for the random blood glucose and urinary glucose testing was 73 and 23%, the specificity was 95 and 99%, the positive predictive value 29 and 48%, and the negative predictive value 99 and 98%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Is serum anhydroglucitol an alternative to the oral glucose tolerance test for diabetes screening? The Mauritius Noncommunicable Diseases Study Group

The oral glucose tolerance test is inconvenient for diabetes screening. In clinical studies a reduced serum anhydroglucitol level has proved to be a sensitive and specific test for diabetes. A new minicolumn enzymatic method which is simple and robust makes use in population screening feasible. The aim of our study was to assess the usefulness of a single measurement of anhydroglucitol to screen for diabetes and impaired glucose tolerance. Assays were performed on samples taken from 227 Mauritian Chinese subjects at the time of glucose tolerance testing. Subjects had normal glucose tolerance (n = 82), impaired glucose tolerance (n = 76), newly diagnosed diabetes (n = 38), and known diabetes (n = 31). Anhydroglucitol concentrations (mean +/- SD) were similar for normal and impaired glucose tolerance subjects (23.7 +/- 8.2 vs 23.4 +/- 8.6 mg l-1). Although the differences between normal and newly diagnosed diabetes (15.0 +/- 11.0 mg l-1) and known diabetic subjects (11.8 +/- 10.6 mg l-1) were significant (p < 0.001), diagnostic sensitivity and specificity were poor. We conclude that measurement of serum anhydroglucitol is not suitable for screening for the diagnoses of impaired glucose tolerance and diabetes.

A comparison of the relationships of the glucose tolerance test and the glycated haemoglobin assay with diabetic vascular disease in the community. The Islington Diabetes Survey

We have compared the relationships of fasting and 2 h blood-glucose during a 75 g oral glucose tolerance test, and those of an affinity chromatography assay of glycated haemoglobin, with the presence of vascular complications of diabetes mellitus in 223 subjects without known diabetes aged over 40 years selected from a community screening study population. The subjects included 15 (6.9%) with newly diagnosed diabetes and 52 (24.1%) with impaired glucose tolerance. Employing receiver operating characteristic analysis, the tests were similar in their relationship with three cases of retinopathy, 19 of microalbuminuria and six of peripheral neuropathy. The prevalence of coronary heart disease, defined as angina, myocardial infarction, or electrocardiographic changes of ischaemia, increased linearly across all four quartiles of both 2 h blood glucose and glycated haemoglobin concentration, but using logistic regression analysis, 2 h blood glucose was a better predictor of coronary heart disease than glycated haemoglobin. Receiver operating characteristic analysis also showed that 2 h blood glucose generally performed better than any of four assays of glycated haemoglobin in classifying those subjects with coronary heart disease.

Self testing for diabetes mellitus

OBJECTIVE

To develop a simple, economically viable, and effective means of population screening for diabetes mellitus.

DESIGN

A postal request system for self testing for glycosuria with foil wrapped dipsticks. Preprandial and postprandial tests were compared with a single postprandial test. The subjects were instructed how to test, and a result card was supplied on which to record and return the result. All those recording a positive test result and 50 people recording a negative result were invited for an oral glucose tolerance test.

SETTING

General practice in east Suffolk, list size 11534.

PATIENTS

All subjects aged 45-70 years registered with the practice were identified by Suffolk Family Health Services Authority (n = 3057). The 73 subjects known to have diabetes from the practice's register were excluded, leaving 2984 subjects, 2363 (79.2%) of whom responded. 1167 subjects completed the single test and 1196 the two tests.

MAIN OUTCOME MEASURES

Response rate and number of patients with glycosuria. Sensitivity, specificity, and positive predictive value of a single postprandial test and preprandial and postprandial tests. Number of new cases of diabetes identified and cost of screening.

RESULTS

Of the patients completing the single postprandial test, 29 had a positive result, an oral glucose tolerance test showed that eight (28%) had diabetes, six (21%) impaired glucose tolerance, and 14 (48%) normal glucose tolerance. 44 of the group who tested before and after eating had a positive result; nine (20%) had diabetes, five (11%) impaired tolerance, and 26 (11%) normal tolerance. Screening cost 59p per subject and 81 pounds per case detected. Of the 17 people with previously undiagnosed diabetes, eight were asymptomatic and 11 had not visited their general practitioner in the past three months.

CONCLUSIONS

A postal request system for self testing for postprandial glycosuria in people aged 45-70 is a simple and effective method of population screening for diabetes mellitus.

Fructosamine in diabetes screening of the elderly

The use of serum fructosamine in diabetes detection was investigated during a diabetes survey performed with a modified oral glucose tolerance test (MOGTT) on 742 residents of the Melton Mowbray area aged between 65 and 85 years. Subjects were tested in the morning and remained at rest. MOGTT results were classified by WHO criteria. The fructosamine concentration was measured in a random sub-group of 264 normal subjects and had a Gaussian distribution (mean = 1.67 mmol/L, SD = 0.126 mmol/L). In the survey as a whole 25 new diabetics were found of which 23 had fructosamine measured; 17 had values above the 95th percentile and four more had values above the 90th percentile. We have found fructosamine concentration to be a useful screen for diabetes but this may be dependent upon the standardized sampling procedure used, and the population studied.

Unexplained variability of glycated haemoglobin in non-diabetic subjects not related to glycaemia

We have studied levels of glycated haemoglobin in a sample of 223 people aged over 40 years without known diabetes mellitus screened in a community study. Each had a glucose tolerance test and glycated haemoglobin measured by four methods - agar gel electrophoresis with and without removal of Schiff base, affinity chromatography and isoelectric focusing. The correlation coefficients between 2 h blood glucose and levels of glycated haemoglobin were between 0.43 and 0.64. This poor correlation was not explained on the basis of assay or biological variability of either 2 h blood glucose or glycated haemoglobin. Multiple regression analysis showed that other assays of glycated haemoglobin contributed to the variance of any single glycated haemoglobin value by 0.1%-52.9% (median 12.8%) compared to the variance of 18.6%-41.4% (median 30.8%) explained by 2 h blood glucose alone, suggesting that in a non-diabetic population, the degree of glucose intolerance may explain only one third of the variance of glycated haemoglobin levels, but other factors operate to produce consistent changes in levels of glycated haemoglobin. Investigation of 42 subjects with consistently high (20 subjects) or low (22 subjects) levels of glycated haemoglobin relative to their 2 h blood glucose level showed no difference in age, gender, body mass index, haemoglobin levels or smoking, although 50% of low glycators had impaired glucose tolerance. Neither ambient blood-glucose levels, as estimated on two five-point blood-glucose profiles, nor dietary intake of carbohydrate, starch, sugars, fibre or alcohol, explained the difference between high and low glycators. The determinants of the consistent interindividual differences in levels of glycated haemoglobin in non-diabetic subjects remain to be determined.

The glycosylated hemoglobin assay for diabetes: its value to the periodontist. Two case reports

The glycosylated hemoglobin assay is a relatively new test used in the diagnosis and monitoring of the diabetic patient. This assay should be of interest to the periodontist as it offers important advantages over traditional blood glucose testing methods. Most importantly, it gives an indication of the blood glucose level over an extended period of time (30 to 90 days), whereas traditional assays only indicate the glucose level at one point in time. Additionally, there is no requirement for fasting prior to testing. Two case reports are presented to illustrate how the glycosylated hemoglobin assay can be utilized by the periodontist.

Screening for diabetes: does measurement of serum fructosamine help?

The diagnostic sensitivity and specificity for diabetes of serum fructosamine levels and fasting venous blood glucose concentrations were compared in 613 subjects during a diabetes community screening programme of 1049 adult Muslim Asians in Dar es Salaam, Tanzania. Using WHO (1985) criteria 228 had impaired glucose tolerance (IGT), 41 had previously been diagnosed as having diabetes while 32 had newly recognized diabetes. The mean (+/- SD) serum fructosamine levels were 20.9 +/- 3.2, 21.6 +/- 3.2, 23.9 +/- 4.9, and 30.1 +/- 7.9 (mumol g-1 albumin) in subjects with normal glucose tolerance, IGT, newly diagnosed diabetes, and previously diagnosed diabetes, respectively (p less than 0.001 for differences between groups). The specificity of values above the mean +2SD normal was 99% for abnormal glucose tolerance with a sensitivity of only 22% for diabetes. The predictive values were 44% and 97% for positive and negative results, respectively. Very little difference from normal was found for IGT subjects. Expressing fructosamine values in absolute terms or per gram albumin made little difference to sensitivity and specificity. The sensitivity was only 32% for fasting blood glucose greater than or equal to 6.7 mmol l-1, 73% for values greater than or equal to 5.5 mmol l-1, and 100% for fasting blood glucose greater than or equal to 4.5 mmol l-1. It is concluded that both serum fructosamine and fasting blood glucose are poor screening and diagnostic tests for diabetes and for IGT, and that glucose loading is required.

Microalbuminuria as predictor of vascular disease in non-diabetic subjects. Islington Diabetes Survey

The relation between urinary albumin excretion rate (AER) and vascular disease was studied in 187 subjects aged over 40 selected from 1084 cases attending a diabetic screening project. AER exceeded 20 micrograms/min in 3 of 13 newly diagnosed diabetic subjects (23%) and 16 of 171 non-diabetic subjects (9.4%). There was a weak relation between AER and both systolic and diastolic blood pressures. Coronary heart disease was found in 54 of 164 (32.9%) subjects with AER of 20 micrograms/min or less and in 14 of 19 (74%) with AER above this. Peripheral vascular disease was present in 16 of 165 (9.7%) subjects with AER of 20 micrograms/min or less and 8 of 18 (44%) with a high AER. Logistic regression, including diabetes, impaired glucose tolerance, systolic and diastolic blood pressures, smoking, age, sex, ethnic origin, and body mass index, demonstrated the independence of this relation between AER above 20 micrograms/min and coronary heart disease (odds ratio [OR] 6.38, 95% confidence interval 1.91-21.4) and peripheral vascular disease (OR 7.72, 2.14-27.8). After a mean of 3.6 (SD 0.19) years, 167 subjects (89.3%) were traced. There had been 9 deaths, 3 (2.0%) among 149 subjects with normal AER and 6 (33%) among 18 microalbuminuric subjects (OR 24.33, 5.40-109.7).

The abbreviated glucose tolerance test in screening for diabetes: the Islington Diabetes Survey

The World Health Organization has recommended a single 2-h post-glucose load blood glucose level as a screening test for diabetes mellitus in epidemiological surveys. We have assessed its characteristics, when compared with a full supervised glucose tolerance test (OGTT), in estimating prevalence, and in diagnosing diabetes in the individual patient. A stratified sample of 223 of 1040 subjects who had participated in a diabetic survey that utilized a single capillary 2-h blood glucose estimation as a screening test were recalled for formal glucose tolerance testing. The numbers of subjects with diabetes at screening and at recall were similar (14/212, 6.6%; 13/216, 6.0%) but only 9 subjects were so classified on both occasions. Thirty-five subjects (16.5%) were suspected of having impaired glucose tolerance (IGT) at screening, and 52 (24.1%) at recall. There was substantial reclassification from screening IGT, with 3/35 worsening to diabetes, and 10/35 returning to normal. Capillary 2-h glucose levels gave an accurate assessment of the prevalence of diabetes but underestimated that of IGT. On the full OGTT, little difference in classification was found when the values of fasting and 1-h blood glucose were used in addition to those of the 2-h blood glucose used alone. The 2-h glucose had a within-subject coefficient of variation of 32.4% which produced substantial reclassification of subjects with levels close to the diagnostic levels for diabetes, and this implies that such individuals should not be classified as having diabetes on the basis of a single glucose tolerance test.(ABSTRACT TRUNCATED AT 250 WORDS)

The glycohaemoglobin assay as a screening test for diabetes mellitus: the Islington Diabetes Survey

Blood glucose 2 h after an oral glucose load (2hBG) and glycohaemoglobin (GHb) (Corning agar-gel electrophoresis) levels were used as screening tests in a general practice diabetic screening programme. The diagnosis of diabetes (DM) was based on a separate oral glucose tolerance test (OGTT) in 223 of 1040 screened subjects, selected as a stratified sample biased towards higher levels of 2hBG and GHb. The GHb assay was also repeated at the recall examination and urine was tested for glycosuria before and after glucose administration. At a cut-off level of 8.1%, the screening GHb assay correctly identified 90% of all probable diabetics with a specificity of 85.3% (95% Cl 83.3-87.3%) and a positive predictive value of 14.0% (9.0-19.0%). The specificity of the screening GHb assay as a screening test for true DM was 45.8% (39.0-52.4%) at 90% sensitivity, and that of the recall GHb assay was 64.5% (57.9-71.1%). The screening 2hBG was 93.3% (88.9-97.7%) specific at 90% sensitivity as a screening test for true DM diagnosed by OGTT at recall. The test characteristics for fasting glycosuria were: sensitivity 16.7% (0-37.8%) and specificity 98.0% (96.0-100.0%). Equivalent values for the post-glucose test for glycosuria were: 72.7% (46.4-99.0%) and 77.4% (70.1-84.7%), respectively. While GHb assay is a poorer screening test for DM than the 2hBG at the single cut-off level quoted, comparison of the accuracy of the two tests shows that the GHb assay is only marginally less accurate. It is superior to testing for glycosuria as a screening test for DM and can be performed on any random blood sample, facilitating its use in population screening.