Insufficient sensitivity of hemoglobin A(₁C) determination in diagnosis or screening of early diabetic states

Momordica balsamina improves glucose handling in a diet-induced prediabetic rat model

Prolonged exposure to high energy diets has been implicated in the development of pre-diabetes, a long-lasting condition that precedes type 2 diabetes mellitus (T2DM). A combination of pharmacological treatment and dietary interventions are recommended to prevent the progression of pre-diabetes to T2DM. However, poor patient compliance leads to negligence of the dietary intervention and thus reduced drug efficiency. Momordica balsamina (MB) has been reported to possess anti-diabetic effects in type 1 diabetic rats. However, the effects of this medicinal plant in conjunction with dietary intervention on pre-diabetes have not yet been established. Consequently, this study sought to evaluate the effects of MB on glucose homeostasis in a diet-induced pre-diabetes rat model in the presence and absence of dietary intervention. Pre-diabetes was induced on male Sprague Dawley rats by a high fat high carbohydrate (HFHC) diet for a period of 20 weeks. Pre-diabetic male Sprague Dawley rats were treated with MB (250 mg/kg p.o.) in both the presence and absence of dietary intervention once a day every third day for a period of 12 weeks. The administration of MB with and without dietary intervention resulted in significantly improved glucose homeostasis through reduced caloric intake, body weights, with reduced plasma ghrelin concentration and glycated hemoglobin by comparison to the pre-diabetic control. MB administration also improved insulin sensitivity as evidenced by the expression of glucose transporter 4 (GLUT 4) and glycogen synthase on the prediabetic treated animals. These results suggest that MB has the potential to be used to manage pre-diabetes and prevent the progression to overt type 2 diabetes as it demonstrated the ability to restore glucose homeostasis even in the absence of dietary and lifestyle intervention.

Use of the new guidelines on an earlier age threshold of 35 years for diabetes screening can identify an additional 6.3 million undiagnosed individuals with diabetes and 72.3 million individuals with prediabetes among Chinese adults: An analysis of a nationally representative survey

BACKGROUND

Young-onset diabetes has been increasingly prevalent in China and most of the young patients with diabetes remain undiagnosed. Recently, the American Diabetes Association (ADA) updated their screening criteria and turned down the age threshold of diabetes screening from 45 years to 35 years, which highlighted the importance of identifying young individuals with diabetes. Herein, we aimed to evaluate the clinical relevance of updated ADA screening recommendations in Chinese adults and the metabolic features and risk factor profiles of these newly diagnosed individuals.

STUDY DESIGN AND METHODS

Using a complex, multistage, probability sampling design, we analyzed data from a nationally representative sample of 98,658 Chinese adults in 2010. Participants without previously diagnosed diabetes were included into the present study. We calculated the proportion of individuals with diabetes eligible for screening and the number needed to screen (NNS) to identify one patient with diabetes by age groups.

RESULTS

Setting an earlier age threshold of diabetes screening can identify additional 6.3 million patients with diabetes and 72.3 million individuals with prediabetes, and the proportion of identified individuals increased more in rural, underdeveloped, and central areas. The NNS in Chinese adults dropped significantly from 28 in 30-34 age group to 15 in 35-45 years of age and remained low afterwards. The undiagnosed patients with diabetes who met the new screening age threshold of ADA recommendation were characterized by younger age, lower blood pressure and blood lipids, but higher proportion of overweight and higher level of insulin resistance, and tended to have an unhealthy diet habit, including low intake of fruits and vegetables and high intake of sugar-sweetened beverages, compared to those aged over 45 years.

CONCLUSIONS

The new age threshold of 35 years for diabetes screening would reduce the proportion of undiagnosed diabetes with high cost-effectiveness, given the NNS for a positive test result was much lower in 35-45 age group comparing to the lower age group in Chinese adults.

The Role of Hemoglobin A1C in Diabetes Screening and Diabetic Retinopathy

Hemoglobin A1C (A1C) is used in various settings. Its performance has not been evaluated systemically. We compared A1C in diagnosis of diabetes with fasting plasma glucose (FPG) and 2-h postchallenged plasma glucose (2hPG) parameters in a cross-sectional cohort in the United Stated. Adult subjects (≥20 years) were identified from the National Health and Nutrition Examination Survey 2005-2016 without a history of diabetes who had BMI, A1C, FPG, and 2hPG (n = 10,416). For comparisons, we calculated the sample weighted prevalence, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) with subgroup analyses. For the retinopathy study, diabetic subjects with established diabetes who responded to the question of diabetic retinopathy were evaluated (n = 3907). Compared to the FPG/2hPG criteria, A1C ≥ 48 mmol/mol (6.5%) had a low sensitivity at 25.90%, with specificity 99.70%, PPV 84.70%, and NPV 95.70%. Subgroup analyses revealed a lower sensitivity in males (24.52%); the lowest in non-Hispanic White (21.35%), in the third decade (14.32%), and in the BMI < 22.50 kg/m2 group (7.21%). The prevalence of self-reported diabetic retinopathy increased drastically with an inflection point at A1C 48 mmol/mol (6.5%) from 11.52% to 18.32% (p < 0.0001). A1C ≥ 48 mmol/mol (6.5%) should be cautiously used to diagnose diabetes in certain subgroups due to very low sensitivity in certain groups. With the confirmation of the association of increasing self-reported diabetic retinopathy with A1C ≥ 48 mmol/mol (6.5%), the current A1C cutoff is an acceptable value with the understanding of especially low sensitivity in certain subgroups.

Role and Risk Factors of Glycosylated Hemoglobin Levels in Early Disease Screening

OBJECTIVE

To clarify the correlation among glycosylated hemoglobin (HbA1c), gender, age, fatty liver, and biochemical indicators through the analysis of big database, and to further investigate the risk factors affecting HbA1c, so as to lay a foundation for the study of HbA1c-related diseases and disease management.

METHODS

People who have been examined in Health Promotion Center from July 2018 to June 2019 were selected as the research objects. All data were analyzed using the Windows R software (version 3.5.1). Detailed medical history inquiry, laboratory examination, and B-ultrasound examination were carried out for the selected sample population. We determined the sample population according to the inclusion and exclusion criteria and, then, further grouped and analyzed the data. T-test or Mann-Whitney U test was used for continuous variable comparison, and chi-square test was used to compare categorical variables. Logistic regression analysis was used to analyze the risk factors of HbA1c.

RESULTS

A total of 23,933 subjects were included in this study. The HbA1c level of men was significantly higher than that of women, the HbA1c level of the group with diabetes was higher than that of the group with no diabetes, and the HbA1c level of the group with fatty liver was higher than that of the group with no fatty liver. In the group with no diabetes, the HbA1c level increased with weight gain. Age, gender (male), fatty liver, waist circumference, systolic blood pressure (SBP), triglyceride (TG), blood urea nitrogen (BUN), free thyroxine (FT4), and red blood cell (RBC) were the risk factors for elevated HbA1c level, while high-density lipoprotein cholesterol (HDL-C), uric acid (UA), creatinine (Cr), free triiodothyronine (FT3), and hemoglobin were protective factors.

CONCLUSION

Blood glucose, age, weight, gender, fatty liver, blood lipids, and UA are related to the increase of HbA1c level. HbA1c is related to many metabolic indexes and may be used as a marker for early detection of chronic diseases.

Predictive Performance of Glycated Hemoglobin for Incident Diabetes Compared with Glucose Tolerance Test According to Central Obesity

BACKGROUND

To examine whether glycated hemoglobin (HbA1c) test would be a suitable screening tool for detecting high-risk subjects for diabetes compared to oral glucose tolerance test (OGTT) according to accompanied central obesity.

METHODS

In this prospective population-based cohort study, both OGTT and HbA1c tests were performed and continued every 2 years up to 12 years among individuals with non-diabetic state at baseline (aged 40 to 69 years, n=7,512). Incident diabetes was established by a doctor, HbA1c ≥6.5%, and/or fasting plasma glucose (FPG) ≥126 mg/dL, and/or 2-hour postprandial glucose (2hPG) level based on OGTT ≥200 mg/dL. Discriminative capacities of high HbA1c (≥5.7%) versus high 2hPG (≥140 mg/dL) for predicting incident diabetes were compared using Cox-proportional hazard regression and C-index.

RESULTS

During the median 11.5 years of follow-up period, 1,341 (17.6%) developed diabetes corresponding to an incidence of 22.1 per 1,000 person-years. Isolated high 2hPG was associated with higher risk for incident diabetes (hazard ratio [HR], 4.29; 95% confidence interval [CI], 3.56 to 5.17) than isolated high HbA1c (HR, 2.79; 95% CI, 2.40 to 3.26; P<0.05). In addition, high 2hPG provided better discriminatory capacity than high HbA1c (C-index 0.79 vs. 0.75, P<0.05). Meanwhile, in subjects with central obesity, the HR (3.95 [95% CI, 3.01 to 5.18] vs. 2.82 [95% CI, 2.30 to 3.46]) and discriminatory capacity of incident diabetes (C-index 0.75 vs. 0.75) between two subgroups became comparable.

CONCLUSION

Even though the overall inferior predictive capacity of HbA1c test than OGTT, HbA1c test might plays a complementary role in identifying high risk for diabetes especially in subjects with central obesity with increased sensitivity.

Plasma glycemic measures and fecundability in a Singapore preconception cohort study

OBJECTIVE

To examine the association between plasma glycemia in women attempting to conceive and fecundability, as measured by time to pregnancy.

DESIGN

Prospective preconception population-based study.

SETTING

Hospital.

PATIENT(S)

Asian preconception women, 18-45 years old, attempting conception for ≤12 cycles at study entry.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

We ascertained time to pregnancy within a year of glycemic assessment in menstrual cycles. We estimated fecundability ratios (FRs) and 95% confidence intervals using discrete-time proportional hazards models, adjusting for age, ethnicity, education, body mass index, and cycle regularity and accounting for left truncation and right censoring.

RESULT(S)

We studied a population sample of 766 women from the Singapore Preconception Study of Long-Term Maternal and Child Outcomes prospective cohort. Compared with women with normoglycemia, women with dysglycemia (prediabetes and diabetes, defined by the American Diabetes Association) had a lower FR (0.56). Compared with the respective lowest quintiles, women in the highest quintile of fasting glucose (≥5.1 mmol/L) had an FR of 0.60, while women in the highest 2-hour postload glucose quintile (≥6.9 mmol/L) had an FR of 0.66. Overall, the FRs decreased generally across the range of fasting and 2-hour plasma glucose. Glycated hemoglobin was not associated with fecundability.

CONCLUSION(S)

Increasing preconception plasma glucose is associated with reduced fecundability, even within the normal range of glucose concentrations.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03531658.

Comparison of 2-Hour Oral Glucose Tolerance Test and Hemoglobin A1C in the Identification of Pre-Diabetes in Women with Infertility and Recurrent Pregnancy Loss

RESEARCH QUESTION

Does hemoglobin A1C (HbA1C) predict pre-diabetes (pre-DM) in a population of women with infertility and/or recurrent pregnancy loss (RPL), when considering the 75 g, 2-hour oral glucose tolerance test (2h GTT) as the gold standard?

DESIGN

Retrospective study of 242 patients with infertility or RPL presenting to a university-affiliated reproductive endocrinology and infertility clinic between January 2012 and December 2016 who underwent screening for disorders of glucose metabolism with a 2h GTT. The prevalence of pre-DM as defined by HbA1C 5.7% to 6.4% and 2h GTT values of 140-199 mg/dL, and predictive values of HbA1C for the identification of pre-DM when compared with 2h GTT, were calculated and compared.

RESULTS

Of 242 patients, 188 (77.7%) women had both HbA1C and 2h GTT performed. Of these, 89 (47.3%) tested positive for pre-DM by one or both methods. Of 89 patients, 14 (15.7%) had both an abnormal 2h GTT and an abnormal HbA1C. Only 6 out of 89 (6.7%) patients tested positive for pre-DM by an abnormal 2h GTT in the setting of a normal HbA1C result. Conversely, 69 of these 89 patients (77.5%) tested positive for pre-DM by an abnormal HbA1C in the setting of a normal 2h GTT. The prevalence of pre-DM, as defined by 2h GTT, was 10.6% (20/188) (95% CI, 6.6-16.0), compared with a prevalence of 44.1% (83/188) (95% CI, 36.9-51.6) when pre-DM was defined by HbA1C alone. When the 2h GTT was considered the gold standard for the identification of pre-DM, the negative predictive value (NPV) of HbA1C compared with 2h GTT was 94.3% (95% CI, 88.0-97.9), whereas the positive predictive value (PPV) of HbA1C compared with 2h GTT was only 16.9% (95% CI, 9.5-26.7).

CONCLUSIONS

Although a normal HbA1C was highly predictive of a normal 2h GTT, the two tests demonstrate poor agreement in the identification of pre-DM in women with infertility and/or RPL. Hemoglobin A1C is superior to the 2h GTT as an initial screening test for pre-DM in this population, since it identified a substantial number of women who would otherwise remain undiagnosed in the setting for a normal 2h GTT alone. However, the long-term clinical relevance of an elevated HbA1C in this population needs to be better defined.

Evaluation of ADA HbA1c criteria in the diagnosis of pre-diabetes and diabetes in a population of Chinese adolescents and young adults at high risk for diabetes: a cross-sectional study

OBJECTIVE

We aimed to assess haemoglobin A1c (HbA1c) for the diagnosis of pre-diabetes and diabetes in a population of Chinese youths at risk of metabolic syndrome.

SETTING

Beijing, China.

PARTICIPANTS

A total of 581 subjects aged 14-28 years underwent evaluation including an oral glucose tolerance test (OGTT). Insulin sensitivity, β-cell function and a number of cardiovascular disease risk factors were evaluated. Receiver operating characteristic (ROC) curves were used to assess the screening efficacy of HbA1c.

RESULTS

Using OGTT data as a standard, the majority (70.0%, 7/10) of subjects with diabetes would have been diagnosed with HbA1c ≥6.5%. In contrast, only 28.1% (16/57) of subjects with pre-diabetes possessed elevated HbA1cs, while the majority (68.4%) had normal HbA1cs. On the contrary, a total of 8.1% (39/479) of youths in the normal HbA1c category (<5.7%) and 21.3% in the pre-diabetes category had pre-diabetes. In the ROC analysis, the area under the curve (AUC) for HbA1c identifying pre-diabetes was 0.680(95% CI 0.640 to 0.719); the optimal threshold was 5.5%, with a sensitivity of 61.4% and specificity of 68.5%. For type 2 diabetes mellitus, the AUC for HbA1c was 0.970 (0.952 to 0.982), and the optimal threshold was 6.1%, with a sensitivity of 90.0% and a specificity of 98.7%. Applying these new cut-offs, pre-diabetic participants (HbA1c 5.5%-6.1%) had lower disposition index and higher risk of dyslipidaemia (OR=1.61,95% CI 1.10 to 2.37) and metabolic syndrome (OR=2.09, 1.27 to 3.45) than those with normal HbA1c (<5.5%).

CONCLUSION

The American Diabetes Association's established HbA1c criteria for pre-diabetes and diabetes (5.7% and 6.5%) may not be appropriately applied to adolescents and young adults in China. Our findings suggest that those with HbA1c of 5.5%-6.1% already exhibit impaired β-cell function and increased cardiometabolic risk factors which may warrant intervention.

TRIAL REGISTRATION NUMBER

NCT03421444.

Optimal hemoglobin A1C cutoff value for diabetes mellitus and pre-diabetes in Pudong New Area, Shanghai, China

AIMS

Due to the diversity of the Chinese population, it requires considerable research to evaluate HbA1c diagnostic threshold for diagnosis of hyperglycemia.

METHODS

We included 7909 subjects aged ≥15 without known diabetes from the baseline of Pudong community cohort in 2013. Participants took oral glucose tolerance test (OGTT) and HbA1c assay. Receiver operating characteristic curve determined the HbA1c threshold in the diagnosis of hyperglycemia.

RESULTS

The optimal HbA1C threshold for diagnosing newly diagnosed diabetes (NDD) and pre-diabetes in this population was 6.0% (AUC=0.798, 95%CI: 0.779-0.818) and 5.6% (AUC=0.655, 95%CI: 0.638-0.671). When compared with elderly age group (≥70 years), HbA1c for detecting NDD performed better in youth (15-39 years: P=0.003, 40-49 years: P<0.001). There were 13.81% and 13.34% of participants would be newly detected as NDD and pre-diabetes via HbA1c criteria; meanwhile 3.20% and 15.52% diagnosed as NDD and pre-diabetes by OGTT criteria would be missed diagnosis.

CONCLUSIONS

The optimal HbA1c thresholds for NDD and pre-diabetes were lower than ADA criteria. It is necessary to carefully consider whether choose HbA1c as a diagnostic criterion or combine two diagnostic standards. Age-specific diagnostic thresholds should be considered when HbA1c was recommended as diagnostic standard.

Fasting Plasma Glucose and the HbA1c Are Not Optimal Screening Modalities for the Diagnosis of New Diabetes in Previously Undiagnosed Asian Indian Community Participants

Objectives

There is no definitive consensus on the screening algorithm in high-risk communities for diabetes. The aims of our study were to determine the prevalence of undiagnosed diabetes in a high-risk community using the oral glucose tolerance test (OGTT), as well as determine the value of anthropometric measurements and other measures of glycemia in the detection of diabetes.

Method

All participants from the Phoenix Lifestyle project without known diabetes, and who had undergone an OGTT were selected for study. Anthropometric measurements were collected according to accepted guidelines. Diabetes was diagnosed if fasting plasma glucose (FPG) ≥7.0 mmol/l, if 2-hour plasma glucose level during OGTT was ≥ 11.0 mmol/l, or if HbA1c ≥ 6.5%.

Results

The prevalence of newly diagnosed diabetes was 14.3% (11.7 % age standardized) (women=15.4%; men=11.8%). The prevalence rates were underestimated using FPG criteria, but overestimated when using the HbA1c. The AUC (area under the receiver-operator characteristics curve) was highest for FPG (.879), HbA1c (.855), then anthropometry measures (BMI=.621; waist circumference=.627). For diabetes, at levels >6.3, the discriminant ability (DA) of HbA1c was highest (79%), while a cut-point of ≥5.5mmol/l for FPG yielded a DA= 81.5% (82% sensitivity; 81%; specificity of 81%). There was a low level of agreement between the FPG (Kappa = .506), HbA1c (Kappa = .537), and the OGTT. Age- and sex-adjusted independent determinants of diabetes using stepwise backward logistic regression were age, triglyceride levels and a positive family history for diabetes.

Conclusion

Neither the HbA1c nor the FPG approached adequate predictive accuracy in the diagnosis of diabetes. In view of the high prevalence of undiagnosed diabetes, this study underscores the need for ongoing national surveillance data.

Comparing glucose and hemoglobin A1c diagnostic tests among a high metabolic risk Hispanic population

BACKGROUND

Compare glycated hemoglobin (HbA1c ) diagnostic tests for prediabetes and diabetes with plasma glucose criteria and compare the metabolic profiles of people classified by HbA1c versus by glucose levels.

METHODS

Participants were recruited for the San Juan Overweight Adults Longitudinal Study. The participants were primarily Hispanic (98%), without previously diagnosed diabetes, and aged 40 to 65 years. Participants classified as normal glycemic, prediabetes, or diabetes on the basis of baseline HbA1c and plasma glucose criteria were compared with respect to baseline cardiometabolic factors.

RESULTS

The 1342 participants had a mean age of 50.5 ± 6.8 years and 28% were men. Thirty-one percent were diagnosed with prediabetes by plasma glucose criteria and 53.4% by HbA1c , and 8.1% were diagnosed with diabetes by plasma glucose criteria and 6.3% by HbA1c ; overall concordance rate was 55.1%. The area under the receiver operating characteristic curve of HbA1c compared to plasma glucose criteria was 0.62 for impaired glucose and 0.76 for diabetes. A worse cardiometabolic profile was seen within subgroups that met HbA1c and plasma glucose criteria for diabetes or prediabetes. Those diagnosed with prediabetes by plasma glucose criteria had significantly higher systolic blood pressure and higher homeostatic model assessment than those diagnosed using HbA1c . Participants diagnosed with diabetes by plasma glucose criteria had lower body mass index, smaller waist circumference, and lower insulinogenic and disposition indices, but higher homeostatic model assessment of insulin resistance, than those diagnosed by HbA1c .

CONCLUSIONS

Low concordance was seen between HbA1c and glucose measurements. The HbA1c is not a good test for prediabetes but shows reasonable validity for diabetes in this high-risk predominantly female Hispanic population. People classified by HbA1c , plasma glucose criteria, or both show different metabolic profiles; a combined test may be ideal.

Fasting glycemia and glycated hemoglobin categories: Relationship to serum lipoprotein(a) level and disparity in 2 geographic regional groups of Turkey

OBJECTIVE

The goal of the present study was to determine covariates of serum lipoprotein (Lp) (a) within fasting glucose and glycated hemoglobin (HbA1c) categories, and to detect features that were different among covariates based on residence in Marmara and Central Anatolia (Marm-CA) regions or remaining 5 geographic regions of Turkey.

METHODS

Data of randomly-selected group of 1167 men and women (mean age 61 years) who participated in biennial surveys of 2013 and 2015 were cross-sectionally analyzed in 6 categories.

RESULTS

In multiple linear regression analysis of nondiabetic women, homeostatic model assessment (HOMA) index score was inversely associated with Lp(a) (ß coefficient 0.49; p=0.001); this was not true for men. In the whole sample, Lp(a) was significantly positively associated with female sex and with serum creatinine, and inversely in each sex with HOMA index (ß coefficient 0.63; p<0.001). Linear models within separate categories showed significant associations of Lp(a) only in individuals with no evidence of diabetes other than HbA1c >6.5%: in women, positive association with total cholesterol and inverse relationship with creatinine were found, and in men, positive association with apolipoprotein (apo) B was determined. Similar age, diastolic blood pressure, fasting glucose, triglyceride, uric acid, and C-reactive protein values were obtained from participants of 2 regional groups. Residents of the Marm-CA region who were nondiabetic exhibited significantly (by 23%) lower serum Lp(a) among individuals with HbA1c ≥5.7%, significantly higher HOMA index score, concentrations of apoB, and low-density lipoprotein cholesterol.

CONCLUSION

Hallmark of prediabetic and diabetic glycemia/HbA1c categories seems to be an independent inverse association between Lp(a) protein (yet not of apoB) and HOMA score, this being primarily so in residents of Marm-CA region.

Detecting prediabetes among Hispanics/Latinos from diverse heritage groups: Does the test matter? Findings from the Hispanic Community Health Study/Study of Latinos

The objectives of this analysis were to compare the ability of fasting plasma glucose (FPG), post oral load plasma glucose (2hPG), and hemoglobin A1c (HbA1c) to identify U.S. Hispanic/Latino individuals with prediabetes, and to assess its cardiovascular risk factor correlates. This is a cross-sectional analysis of baseline data from 15,507 adults without self-reported diabetes mellitus from six Hispanic/Latino heritage groups, enrolled in the Hispanic Community Health Study/Study of Latinos, which takes place in four U.S. communities. The prevalence of prediabetes was determined according to individual or combinations of ADA-defined cut points: FPG=5.6-7.0mmol/L, 2hPG=7.8-11.1mmol/L, and HbA1c=5.7%-6.4% (39-46mmol/mol). The sensitivity of these criteria to detect prediabetes was estimated. The prevalence ratios (PRs) for selected cardiovascular risk factors were compared among alternative categories of prediabetes versus normoglycemia [FPG<5.6mmol/L and 2hPG<7.8mmol/L and HbA1c<5.7% (39mmol/mol)]. Approximately 36% of individuals met any of the ADA prediabetes criteria. Using 2hPG as the gold standard, the sensitivity of FPG was 40.1%, HbA1c was 45.6%, and that of HbA1c+FPG was 62.2%. The number of significant PRs for cardiovascular risk factors was higher among individuals with isolated 2hPG=7.8-11.1mmol/L, FPG=5.6-7.0mmol/L+HbA1c=5.7%-6.4%, or those who met the three prediabetes criteria. Assessing FPG, HbA1c, and cardiovascular risk factors in Hispanics/Latinos at risk might enhance the early prevention of diabetes mellitus and cardiovascular complications in this young and growing population, independent of their heritage group.

PERFORMANCE OF A1C VERSUS OGTT FOR THE DIAGNOSIS OF PREDIABETES IN A COMMUNITY-BASED SCREENING

OBJECTIVE

Reliable identification of individuals at risk for developing diabetes is critical to instituting preventative strategies. Studies suggest that the accuracy of using hemoglobin A1c as a sole diagnostic criterion for diabetes may be variable across different ethnic groups. We postulate that there will be lack of concordance between A1c and the oral glucose tolerance test (OGTT) for diagnosing prediabetes across Hispanic and non-Hispanic white (NHW) populations.

METHODS

A total of 218 asymptomatic adults at risk for type 2 diabetes (T2D) were assessed with A1c and OGTT for the diagnosis of prediabetes. Glucose homeostasis status was assigned as no diabetes (A1c <5.7% [39 mmol/mol]), prediabetes (A1c 5.7 to 6.4% [46 mmol/mol]), and T2D (A1c >6.4% [46 mmol/mol]). Inclusion criteria were age >18 years and at least one of the following: a family history of diabetes, a history of gestational diabetes, Hispanic ethnicity, non-Caucasian race, or obesity. Subjects received a fasting 75-g OGTT and A1c on the same day. Bowker's test of symmetry was employed to determine agreement between the tests.

RESULTS

Data from 99 Hispanic patients and 79 NHW patients were analyzed. There was no concordance between A1c and OGTT for Hispanic (P = .002) or NHW individuals (P = .003) with prediabetes.

CONCLUSION

A1c is discordant with OGTT among Hispanic and NHW subjects for the diagnosis of prediabetes. Sole use of A1c to designate glycemic status will result in a greater prevalence of prediabetes among Hispanic and NHW New Mexicans.

ABBREVIATIONS

A1c = hemoglobin A1c BMI = body mass index CDC = Centers for Disease Control CI = confidence interval FPG = fasting plasma glucose NHW = non-Hispanic white OGTT = oral glucose tolerance test T2D = type 2 diabetes WHO = World Health Organization.

Standardising HbA1c-based diabetes diagnosis: opportunities and challenges

Globally, the incidence of diabetes mellitus is rising at an alarming rate and has become a health crisis that threatens the economies of all nations. Therefore, diagnosing diabetes has become an important issue in the management of diabetes. Glycated hemoglobin (HbA1c) is now recommended as a means to diagnose diabetes, but its use still has limitations. In this article, the biology, measurement, standardization, and opportunities and challenges of the use of HbA1c to diagnose diabetes are reviewed. More specifically, its use in China and the Asian region is discussed in detail.

Comparison of the Current Diagnostic Criterion of HbA1c with Fasting and 2-Hour Plasma Glucose Concentration

To determine the effectiveness of hemoglobin A1c (HbA1c) ≥ 6.5% in diagnosing diabetes compared to fasting plasma glucose (FPG) ≥ 126 mg/dL and 2-hour plasma glucose (2hPG) ≥ 200 mg/dL in a previously undiagnosed diabetic cohort, we included 5,764 adult subjects without established diabetes for whom HbA1c, FPG, 2hPG, and BMI measurements were collected. Compared to the FPG criterion, the sensitivity of HbA1c ≥ 6.5% was only 43.3% (106 subjects). Compared to the 2hPG criterion, the sensitivity of HbA1c ≥ 6.5% was only 28.1% (110 subjects). Patients who were diabetic using 2hPG criterion but had HbA1c < 6.5% were more likely to be older (64 ± 15 versus 60 ± 15 years old, P = 0.01, mean ± STD), female (53.2% versus 38.2%, P = 0.008), leaner (29.7 ± 6.1 versus 33.0 ± 6.6 kg/m(2), P = 0.000005), and less likely to be current smokers (18.1% versus 29.1%, P = 0.02) as compared to those with HbA1c ≥ 6.5%. The diagnostic agreement in the clinical setting revealed the current HbA1c ≥ 6.5% is less likely to detect diabetes than those defined by FPG and 2hPG. HbA1c ≥ 6.5% detects less than 50% of diabetic patients defined by FPG and less than 30% of diabetic patients defined by 2hPG. When the diagnosis of diabetes is in doubt by HbA1c, FPG and/or 2hPG should be obtained.

Low positive predictive value of hemoglobin A1c for diagnosis of prediabetes in clinical practice

BACKGROUND

Positive predictive value (PPV) of hemoglobin A1c (HbA1c) for diagnosis of prediabetes in clinical practice has not been well studied.

METHODS

In a prospective study, patients diagnosed with prediabetes based on HbA1c (5.7%-6.4%) underwent a 75-g oral glucose tolerance test (OGTT) as the gold standard test to diagnose dysglycemia. Demographics, anthropometrics, comorbidity, concomitant prescription medications and biochemical data were collected.

RESULTS

We identified 66 patients with HbA1c-based prediabetes with a mean HbA1c of 6.00 ± 0.20%. However, based on the OGTT, 32 had normal glucose tolerance (NGT), 26 had prediabetes and 8 had diabetes yielding a PPV of HbA1c of 39.4%. In univariate analysis, the patients with the OGTT-based prediabetes administered more medications for associated medical problems compared with the NGT group (5.9 ± 2.2 versus 2.6 ± 1.8, P < 0.0001). After adjustment for baseline variables, the medication use remained significantly different between OGTT-based prediabetes and NGT groups (P = 0.041).

CONCLUSIONS

PPV of HbA1c for diagnosis of prediabetes in clinical setting is low. Patients with HbA1c of 5.7% to 6.4% should undergo OGTT to confirm diagnosis of dysglycemia.

Significance of HbA1c and its measurement in the diagnosis of diabetes mellitus: US experience

The 2014 American Diabetes Association guidelines denote four means of diagnosing diabetes. The first of these is a glycosylated hemoglobin (HbA1c) >6.5%. This literature review summarizes studies (n=47) in the USA examining the significance, strengths, and limitations of using HbA1c as a diagnostic tool for diabetes, relative to other available means. Due to the relatively recent adoption of HbA1c as a diabetes mellitus diagnostic tool, a hybrid systematic, truncated review of the literature was implemented. Based on these studies, we conclude that HbA1c screening for diabetes has been found to be convenient and effective in diagnosing diabetes. HbA1c screening is particularly helpful in community-based and acute care settings where tests requiring fasting are not practical. Using HbA1c to diagnose diabetes also has some limitations. For instance, HbA1c testing may underestimate the prevalence of diabetes, particularly among whites. Because this bias differs by racial group, prevalence and resulting estimates of health disparities based on HbA1c screening differ from those based on other methods of diagnosis. In addition, existing evidence suggests that HbA1c screening may not be valid in certain subgroups, such as children, women with gestational diabetes, patients with human immunodeficiency virus, and those with prediabetes. Further guidelines are needed to clarify the appropriate use of HbA1c screening in these populations.

Prediabetic increase in hemoglobin A1c compared with impaired fasting glucose in patients receiving antipsychotic drugs

BACKGROUND

In 2010, the American Diabetes Association recommended that individuals with hemoglobin A1c 5.7-6.4% be classified as prediabetic even in the absence of impaired fasting glucose (IFG).

AIM OF STUDY

To compare the clinical and metabolic characteristics of patients receiving antipsychotic drugs who have normal glucose tolerance (NGT), hemoglobin A1c 5.7-6.4% or IFG (fasting glucose 100-125 mg/dL).

METHOD

Body mass index, waist circumference, fasting glucose, insulin, lipids, hemoglobin A1c, and insulin resistance assessed with the homeostatic model (HOMA-IR) were measured in a consecutive cohort of adult psychiatric inpatients with NGT (N = 423), hemoglobin A1c 5.7-6.4% (N = 130), IFG (N = 52) and IFG plus hemoglobin A1c 5.7-6.4% (n = 39).

RESULTS

The hemoglobin A1c 5.7-6.4% group had lower fasting insulin levels (9.8 ± 5.6 vs. 15.5 ± 11.4 μU/mL, p < 0.0001) and HOMA-IR (2.1 ± 1.2 vs. 4.1 ± 3.1, p < 0.0001) than the IFG group, but were metabolically similar to those with NGT. The hemoglobin A1c 5.7-6.4% was the predominant prediabetic pattern in patients treated with antipsychotics other than clozapine or olanzapine. Patients with hemoglobin A1c 5.7-6.4% and those with IFG were statistically similar in age (40.1 ± 13.6 vs. 39.7 ± 10.3 years), body mass index (26.0 ± 4.8 vs. 26.3 ± 4.9) and waist circumference 93.1 ± 13.9 vs. 98.1 ± 12.1 cm for males and 92.5 ± 13.5 vs. 90.7 ± 15.8 cm for females.

CONCLUSION

The hemoglobin A1c in the 5.7-6.4% range is common in euglycemic patients receiving antipsychotic drugs and this prediabetic pattern has metabolic and pharmacological features that differentiates it from IFG.

Use of glucometer and fasting blood glucose as screening tools for diabetes mellitus type 2 and glycated haemoglobin as clinical reference in rural community primary care settings of a middle income country

Background

Thailand is considered to be a middle income country, and to control and prevent type 2 diabetes mellitus (T2DM) is one of the main concerns of the Thai Ministry of Public Health (MoPH). Screening for T2DM and care for T2DM patients has been integrated into the primary health care system, especially in rural areas. The intention of this investigation is to link public health research at the academic level with the local health authorities of a district of a north-eastern province of the country.

Methods

Epidemiological methods were applied to validate the screening tools fasting capillary blood glucose (CBG), measured by glucometer and venous blood for the determination of plasma glucose (VPG), used for screening for T2DM among asymptomatic villagers. For assessing the validity of these two methods glycated haemoglobin (HbA1c) values were determined and used as the ‘clinical reference’.

Results

All together 669 villagers were investigated. Determinations of CBG and VPG resulted in suspected T2DM cases, with 7.3% when assessed by CBG and 6.4% by VPG using a cutoff point of 7 mmol/L (126 mg/dl). Taking HbA1c determinations with a cutoff point of 7% into account, the proportion of T2DM suspected participants increased to 10.4%. By estimating sensitivity, specificity and the positive predictive value of CBG and VPG against the ‘clinical reference’ of HbA1c, sensitivity below 50% for both screening methods has been observed. The positive predictive value was determined to be 58.5% for CBG and 56.8% for VPG. The specificity of the two screening tests was over 96%.

Conclusions

The low sensitivity indicates that using fasting CBG or VPG as a screening tool in the field results in a high proportion of diseased individuals remaining undetected. The equally low positive predictive values (below 60%) indicate a high working load for the curative sector in investigating suspected T2DM cases to determine whether they are truly diseased or false positive cases according to the screening method. Further implications of the results and the controversial discussion related to the use of HbA1c as clinical evidence for suffering from T2DM are also discussed.

Controversies on how diabetes is diagnosed

PURPOSE OF REVIEW

To evaluate the controversial aspects of diabetes diagnosis.

RECENT FINDINGS

Within the past 2 years, revised guidelines for the diagnosis of diabetes have been issued which endorse the use of the hemoglobin A1C as a diagnostic test, in addition to the previously recommended tests. Updated diagnostic criteria for gestational diabetes were also published in the same period. Recent publications on the current role of oral glucose tolerance tests and diagnosis of diabetes in the acutely ill are sparse. There are new recommendations regarding the use of genetic testing and antibody testing in establishing the cause of diabetes.

SUMMARY

The inclusion of A1C as a diagnostic test has many advantages including reproducibility of the test and convenience, but there are situations where the test is unreliable and it misses many individuals who would have been diagnosed by plasma glucose testing. The diagnostic threshold of 6.5% for the A1C remains controversial. There is still no consensus on the best approach to diagnose gestational diabetes. The role of the oral glucose tolerance test seems to be diminishing. Diagnosis of diabetes in acute illness is aided by A1C testing. Genetic and autoantibody testing in specific situations offer diagnostic and therapeutic utility.

Serum resistance to singlet oxygen in patients with diabetes mellitus in comparison to healthy donors

Diabetes mellitus causes endothelial injury through oxidative stress involving reactive oxygen species and peroxides as well as inflammation, both of which consume antioxidant defenses. Singlet oxygen ((1)O(2)) is produced by leukocytes during inflammatory and biochemical reactions and deactivated by producing reactive oxygen species and peroxides. To determine whether serum was capable of deactivating (1)O(2), we triggered a photo reaction in sera from 53 healthy donors and 52 diabetic patients. Immediately after light delivery, dichlorofluorescein was added and then its fluorescence was recorded. The mean capacity of (1)O(2) or secondary oxidant deactivation was reduced in patients with diabetes mellitus. Hemolysis reduced deactivation of (1)O(2)-induced secondary oxidants in both healthy and diabetic patients. Body mass index, age, platelet counts, and blood cell numbers exerted a nonlinear influence. High levels of glycated hemoglobin were associated with an increased deactivation of oxidative species, whereas high-density lipoprotein cholesterol, total cholesterol, and the total cholesterol to high-density lipoprotein cholesterol ratio decreased the serum deactivation capacity. Oral antidiabetics bore no influence on deactivation, which was restored by insulin in women. Deactivation capacity was lower in women, who had half the complications found in men, suggesting that, with more severe diabetes mellitus, protection was maintained against complications. Resistance to (1)O(2) should be considered during the monitoring of diabetes mellitus.

Implications of using hemoglobin A1C for diagnosing diabetes mellitus

Until 2010, the diagnosis of diabetes mellitus was based solely on glucose concentration, but the American Diabetes Association (ADA) recommendations now include a new criterion: hemoglobin A1C ≥6.5%. Because this change may have significant implications for diabetes diagnosis, we conducted a comprehensive literature review including peer-reviewed articles not referenced in the ADA report. We conclude that A1C and plasma glucose tests are frequently discordant for diagnosing diabetes. A1C ≥6.5% identifies fewer individuals as having diabetes than glucose-based criteria. Convenience of A1C test might increase the number of patients diagnosed, but this is unproven. Diagnostic cut-points for both glucose and A1C are based on consensus judgments regarding optimal sensitivity and specificity for the complications of hyperglycemia. A1C may not accurately reflect levels of glycemia in some situations, but in comparison with glucose measurements, it has greater analytic stability and less temporal variability. When choosing a diagnostic test for diabetes, the limitations of each choice must be understood. Clinical judgment and consideration of patient preference are required to appropriately select among the diagnostic alternatives.