Fasting plasma glucose in screening for diabetes in the Taiwanese population

The Oral Glucose Tolerance Test: 100 Years Later

For over 100 years, the oral glucose tolerance test (OGTT) has been the cornerstone for detecting prediabetes and type 2 diabetes (T2DM). In recent decades, controversies have arisen identifying internationally acceptable cut points using fasting plasma glucose (FPG), 2-h post-load glucose (2-h PG), and/or HbA1c for defining intermediate hyperglycemia (prediabetes). Despite this, there has been a steadfast global consensus of the 2-h PG for defining dysglycemic states during the OGTT. This article reviews the history of the OGTT and recent advances in its application, including the glucose challenge test and mathematical modeling for determining the shape of the glucose curve. Pitfalls of the FPG, 2-h PG during the OGTT, and HbA1c are considered as well. Finally, the associations between the 30-minute and 1-hour plasma glucose (1-h PG) levels derived from the OGTT and incidence of diabetes and its complications will be reviewed. The considerable evidence base supports modifying current screening and diagnostic recommendations with the use of the 1-h PG. Measurement of the 1-h PG level could increase the likelihood of identifying high-risk individuals when the pancreatic ß-cell function is substantially more intact with the added practical advantage of potentially replacing the conventional 2-h OGTT making it more acceptable in the clinical setting.

Developing a Screening Algorithm for Type II Diabetes Mellitus in the Resource-Limited Setting of Rural Tanzania

BACKGROUND

Noncommunicable diseases are on pace to outnumber infectious disease as the leading cause of death in sub-Saharan Africa, yet many questions remain unanswered with concern toward effective methods of screening for type II diabetes mellitus (DM) in this resource-limited setting. We aim to design a screening algorithm for type II DM that optimizes sensitivity and specificity of identifying individuals with undiagnosed DM, as well as affordability to health systems and individuals.

METHODS

Baseline demographic and clinical data, including hemoglobin A1c (HbA1c), were collected from 713 participants using probability sampling of the general population. We used these data, along with model parameters obtained from the literature, to mathematically model 8 purposed DM screening algorithms, while optimizing the sensitivity and specificity using Monte Carlo and Latin Hypercube simulation.

RESULTS

An algorithm that combines risk assessment and measurement of fasting blood glucose was found to be superior for the most resource-limited settings (sensitivity 68%, sensitivity 99% and cost per patient having DM identified as $2.94). Incorporating HbA1c testing improves the sensitivity to 75.62%, but raises the cost per DM case identified to $6.04. The preferred algorithms are heavily biased to diagnose those with more severe cases of DM.

CONCLUSIONS

Using basic risk assessment tools and fasting blood sugar testing in lieu of HbA1c testing in resource-limited settings could allow for significantly more feasible DM screening programs with reasonable sensitivity and specificity.

Impaired baroreflex sensitivity in subjects with impaired glucose tolerance, but not isolated impaired fasting glucose

Impaired baroreflex sensitivity (BRS) is associated with adverse cardiovascular outcomes. There are currently no studies on BRS changes in subjects with different glycemic statuses, including normal glucose tolerance (NGT), isolated impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and newly diagnosed diabetes (NDD). The aim of this study was to investigate the effects of NDD, IGT and isolated IFG on BRS, based on a community-based data. A total of 768 subjects were classified as NGT (n = 498), isolated IFG (n = 61), IGT (n = 126) and NDD (n = 83). Spontaneous BRS was determined by the spectral α coefficient method, i.e., the square root of the ratio between the power of the RR interval and the power of systolic blood pressure in the LF frequency region (0.04-0.15 Hz) after the subjects had rested in a supine position for 5 min. Valsalva ratio was calculated as the longest RR interval after release of the Valsalva maneuver, divided by the shortest RR interval during the maneuver. As compared with NGT subjects, NDD (p = 0.039) and IGT (p = 0.041) subjects had a reduced spontaneous BRS in multivariate analysis based on analysis of covariance. NDD subjects exhibited a lower Valsalva ratio than NGT subjects (p = 0.043). However, there were no significant differences in spontaneous BRS and Valsalva ratio between subjects with isolated IFG and NGT. In conclusion, NDD and IGT subjects had an impaired BRS as compared to NGT subjects. However, reduced BRS was not apparent in subjects with isolated IFG.

Glucose challenge test screening for prediabetes and undiagnosed diabetes

AIMS/HYPOTHESIS

Diabetes prevention and care are limited by lack of screening. We hypothesised that screening could be done with a strategy similar to that used near-universally for gestational diabetes, i.e. a 50 g oral glucose challenge test (GCT) performed at any time of day, regardless of meal status, with one 1 h sample.

METHODS

At a first visit, participants had random plasma and capillary glucose measured, followed by the GCT with plasma and capillary glucose (GCTplasma and GCTcap, respectively). At a second visit, participants had HbA(1c) measured and a diagnostic 75 g OGTT.

RESULTS

The 1,573 participants had mean age of 48 years, BMI 30.3 kg/m(2) and 58% were women and 58% were black. Diabetes (defined by WHO) was present in 4.6% and prediabetes (defined as impaired glucose tolerance [2 h glucose 7.8-11.1 (140-199 mg/dl) with fasting glucose <or=6.9 (125 mg/dl)] and/or impaired fasting glucose with plasma glucose 6.1-6.9 mmol/l [110-125 mg/dl]) in 18.7%. The GCTplasma provided areas under the receiver-operating-characteristic curves of 0.90, 0.82 and 0.79 for detection of diabetes, diabetes or prediabetes, and prediabetes, respectively, all of which were higher than GCTcap, random and capillary glucose, and HbA(1c) (p < 0.02 for all). The performance of GCTplasma was unaffected by time after meals or time of day, and was better in blacks than whites, but otherwise comparable in men and women, and in groups with differing prevalence of glucose intolerance. GCTplasma screening would cost approximately US$84 to identify one person with previously unrecognised diabetes or prediabetes.

CONCLUSIONS/INTERPRETATION

GCT screening for prediabetes and previously unrecognised diabetes would be accurate, convenient and inexpensive. Widespread use of GCT screening could help improve disease management by permitting early initiation of therapy aimed at preventing or delaying the development of diabetes and its complications.

Fasting plasma glucose cutoff for diagnosis of diabetes in a Japanese population

OBJECTIVE

We examined the relationship between fasting plasma glucose (FPG) and 2-h post-load glucose (PG) levels, and the optimal FPG cutoff level to correspond to a 2-h PG of 11.1 mmol/liter, the gold standard diagnostic criterion, in a general Japanese population.

DESIGN

Cross-sectional study populations of 2421 subjects in 1988 and 2698 subjects in 2002, aged 40-79 yr and without antidiabetic medication, were tested with an oral glucose tolerance test. The relationship between FPG and 2-h PG was investigated by various regression models and a receiver operating characteristic curve.

RESULTS

The best-fit model for the relationship between FPG and 2-h PG was a quadratic regression model. The FPG cutoff levels corresponding to the 2-h PG of 11.1 mmol/liter by this model were 6.2 mmol/liter in 1988 and 6.3 mmol/liter in 2002. In the combined populations, the FPG cutoff point was 6.3 mmol/liter; the sensitivity and specificity of this cutoff point for detecting a 2-h PG of 11.1 mmol/liter were 75.2 and 88.6%, respectively. The receiver operating characteristic curve analysis confirmed that the corresponding FPG point was 6.2 mmol/liter in both the 1988 and 2002 populations. In a stratified analysis, the FPG cutoff level increased with increasing body mass index levels; however, even in subjects with body mass index more than or equal to 30 kg/m2, the FPG cutoff level was lower than 7.0 mmol/liter.

CONCLUSIONS

Our findings suggest that the FPG cutoff level corresponding to the 2-h PG of 11.1 mmol/liter in the general Japanese population is lower than the current diagnostic criterion.

Targeted screening for undiagnosed diabetes reduces the number of diagnostic tests. Inter99(8)

AIMS

To determine the cost and performance of a Danish risk score, fasting plasma glucose (FPG), and HbA1c as single screening tests and in combination with targeted screening.

SUBJECTS AND METHODS

In the Inter99 study, 12 934 inhabitants of Copenhagen County were invited to participate. All participants underwent anthropometric measurements, blood samples, and a 75-g standardized oral glucose tolerance test [N = 6784 (52.5%)].

RESULTS

Of the 6117 individuals included in the analysis, 252 (4.1%) had previously undiagnosed diabetes. As a stand-alone test, the FPG had the highest performance expressed by a significantly higher area under the receiver-operating curve [0.89; 95% confidence interval (CI) 0.86, 0.99] compared with the Danish risk score (0.78; 95% CI 0.76, 0.81) and HbA1c (0.76; 95% CI 0.72, 0.80). Targeted screening where the initial test was a risk score reduced the FPG measurements by 72% (100% vs. 27.8%). Using FPG in population-based screening, the cost per newly diagnosed diabetic individual was 583 euro compared with 270 euro if screened by questionnaire followed by FPG. The sensitivity and specificity were 78.6% and 87.7% for FPG, and 61.5% and 89.2% for the combination of the questionnaire and FPG, respectively.

CONCLUSIONS

The performance of FPG was superior to a questionnaire and HbA1c used as single tests. However taking into account workload, the burden on the population and the cost per identified person with undiagnosed diabetes, targeted screening using a questionnaire followed by FPG appears to be the strategy of choice.

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.

Diagnosis of diabetes mellitus and intermediate glucose abnormalities in obese patients based on ADA (1997) and WHO (1985) criteria

AIM

To assess the accuracy of the 1997 ADA criteria for diagnosing diabetes mellitus and related glucose disturbances in comparison with the reference WHO 1985 criteria in obese subjects.

PATIENTS AND METHODS

In 286 men and 881 women, 15-84 years of age, with obesity (body mass index (BMI) > or = 30 kg/m2), an oral glucose tolerance test (OGTT) was carried out according to WHO standard. Patients were classified into three categories of glucose tolerance using WHO 1985 (Normal Glucose Tolerance (NGT), Impaired Glucose Tolerance (IGT) and Diabetes Mellitus (DM)) and ADA (Normal Fasting Glucose (NFG), Impaired Fasting Glucose (IFG) and DM) criteria. Prevalence of each category was compared and agreement between the two classifications was assessed. The relation between fasting plasma glucose value and diabetes, as diagnosed by WHO 1985 criteria, was studied using various regression models, cumulative frequency curves, Finch method and ROC curve.

RESULTS

Compared with WHO 1985, ADA criteria strongly underestimated the prevalence rate of diabetes (3.7% vs. 10.6%) and intermediate glucose abnormalities (6.0% vs. 22.4%). Agreement between the two classifications was poor (kappa = 0.23). Moreover, many patients defined as glucose-intolerant by the WHO 1985 criteria were shifted to a more favourable metabolic status by ADA criteria. Thus, ADA criteria failed to detect 69% of WHO diabetic patients and 89% with IGT were considered as normal. According to the method, cut-off value of fasting blood glucose for detecting WHO 1985-diagnosed diabetes varied widely, from 5.3 to 6.3 mmol/l and none was satisfactory because of poor sensitivity and positive predictive value.

CONCLUSION

The ADA criteria do not appear to be a good substitute for those of the WHO 1985 at identifying diabetes and intermediate glucose abnormalities in an obese population. Since it appears impossible to determine a reliable cut-off value for fasting blood glucose to identify diabetic obese subjects with sufficient sensitivity, our results justify the retention of the OGTT in clinical practice or for epidemiological studies.

Abnormal glucose tolerance and increased risk for cardiovascular disease in Japanese-Americans with normal fasting glucose

OBJECTIVE

To compare the American Diabetes Association (ADA) fasting glucose and the World Health Organization (WHO) oral glucose tolerance test (OGTT) criteria for diagnosing diabetes and detecting people at increased risk for cardiovascular disease (CVD).

RESEARCH DESIGN AND METHODS

Study subjects were 596 Japanese-Americans. Fasting insulin, lipids, and C-peptide levels; systolic and diastolic blood pressures (BPs); BMI (kg/m2); and total and intra-abdominal body fat distribution by computed tomography (CT) were measured. Study subjects were categorized by ADA criteria as having normal fasting glucose (NFG), impaired fasting glucose (IFG), and diabetic fasting glucose and by WHO criteria for a 75-g OGTT as having normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and diabetic glucose tolerance (DGT).

RESULTS

Of 503 patients with NFG, 176 had IGT and 20 had DGT These patients had worse CVD risk factors than those with NGT . The mean values for NGT, IGT, and DGT, respectively, and analysis of covariance P values, adjusted for age and sex, are as follows; intra-abdominal fat area by CT 69.7, 95.0, and 101.1 cm2 (P < 0.0001); total CT fat area 437.7, 523.3, and 489.8 cm2 (P < 0.0001); fasting triglycerides 1.40, 1.77, and 1.74 mmol/l (P = 0.002); fasting HDL cholesterol 1.56, 1.50, and 1.49 mmol/l (P = 0.02); C-peptide 0.80, 0.90, 0.95 nmol/l (P = 0.002); systolic BP 124.9, 132.4, and 136.9 mmHg (P = 0.0035); diastolic BP 74.8, 77.7, and 78.2 mmHg (P = 0.01).

CONCLUSIONS

NFG patients who had IGT or DGT had more intra-abdominal fat and total adiposity; higher insulin, C-peptide, and triglyceride levels; lower HDL cholesterol levels; and higher BPs than those with NGT. Classification by fasting glucose misses many Japanese-Americans with abnormal glucose tolerance and less favorable cardiovascular risk profiles.

New ADA criteria in the Korean population: fasting blood glucose is not enough for diagnosis of mild diabetes especially in the elderly

BACKGROUND

To compare the 1997 American Diabetes Association (ADA) criteria with the 1985 World Health Organization (WHO) criteria in categorization of the diabetes diagnostic status of Koreans and to define clinical characteristics of subjects diagnosed differently by the two criteria.

METHODS

In 810 Korean subjects, we analyzed blood glucose and insulin response during 75 g oral glucose tolerance test (OGTT). According to current WHO criteria, the cutoff values of FPG which distinguish normal and IGT from diabetes were determined. Then the subjects were categorized according to both WHO and ADA criteria. The clinical characteristics of the subjects with different diagnostic categories by the two criteria were defined.

RESULTS

The FPG cut point distinguishing diabetes from IGT was 117 mg/dl, and from normal was 110 mg/dl. The overall agreement between the ADA criteria and the WHO criteria was moderate, as reflected in the kappa of 0.45. 141 of subjects categorized diabetes by WHO criteria were not diagnosed with ADA criteria. These discordant subjects were older in age and showed blunted early insulin response than concordant normal subjects.

CONCLUSION

These results suggest that mild diabetes by the WHO criteria, especially in the elderly, would not be diagnosed as diabetes by the ADA FPG criteria only. Thus, in a group at high risk for developing diabetes or in a relatively older age group, we should continue using the OGTT.

Comparison of WHO and ADA criteria for diagnosis of glucose status in adults

The aim was to compare the 1997 American Diabetes Association (ADA) and 1985 and 1998 World Health Organisation (WHO) criteria for the diagnosis of diabetes and impaired glucose tolerance (IGT) by ethnicity and cardiovascular risk factors. We analysed the oral glucose tolerance tests carried out in a cross-sectional survey of 5816 New Zealand workers aged 22-78 years (4211 men, 1605 women) carried out between 1988 and 1990. Prevalence of diabetes was similar using ADA (3.1%) compared with the 1998 WHO criteria (3.0%). The overall prevalence rate of diabetes using the 1985 WHO criteria was only 1.5%. The prevalence rate of impaired fasting glucose (IFG) was the lowest in Europeans (7.3%) and highest in Asians (15.0%). The overall weighted kappa for agreement between the 1997 ADA and 1998 WHO criteria was moderate (0.59), but varied between ethnic groups. Cardiovascular disease (CVD) risk factors were approximately more adverse across groups with IFG, normal (ADA)/IGT (WHO), IFG/IGT and diabetes compared with normal subjects. Compared to those with IFG, participants with the normal (ADA)/IGT (WHO) criteria differed in fasting and 2-h glucose, diastolic blood pressure, and urinary albumin levels, and the proportions of males and number with hypertension, but had a significantly adverse pattern of CVD risk factors compared to those with normal glycaemia. The 1988 WHO criteria using the OGTT provides additional information for classifying various categories of glucose intolerance that is not captured using the 1997 ADA fasting glucose criteria alone.

Globalization, coca-colonization and the chronic disease epidemic: can the Doomsday scenario be averted?

There are at present approximately 110 million people with diabetes in the world but this number will reach over 220 million by the year 2010, the majority of them with type 2 diabetes. Thus there is an urgent need for strategies to prevent the emerging global epidemic of type 2 diabetes to be implemented. Tackling diabetes must be part of an integrated program that addresses lifestyle related disorders. The prevention and control of type 2 diabetes and the other major noncommunicable diseases (NCDs) can be cost- and health-effective through an integrated (i.e. horizontal) approach to noncommunicable diseases disease prevention and control. With the re-emergence of devastating communicable diseases including AIDS, the Ebola virus and tuberculosis, the pressure is on international and regional agencies to see that the noncommunicable disease epidemic is addressed. The international diabetes and public health communities need to adopt a more pragmatic view of the epidemic of type 2 diabetes and other noncommunicable diseases. The current situation is a symptom of globalization with respect to its social, cultural, economic and political significance. Type 2 diabetes will not be prevented by traditional medical approaches; what is required are major and dramatic changes in the socio-economic and cultural status of people in developing countries and the disadvantaged, minority groups in developed nations. The international diabetes and public health communities must lobby and mobilize politicians, other international agencies such as UNDP, UNICEF, and the World Bank as well as other international nongovernmental agencies dealing with the noncommunicable diseases to address the socio-economic, behavioural, nutritional and public health issues that have led to the type 2 diabetes and noncommunicable diseases epidemic. A multidisciplinary Task Force representing all parties which can contribute to a reversal of the underlying socio-economic causes of the problem is an urgent priority.