Applicability of a combination of hemoglobin A(1c) and fasting plasma glucose in population-based prediabetes screening

Establishment of reference interval for hemoglobin A1C and other hemoglobin subfractions for healthy Saudi adults

BACKGROUND

The establishment of Reference Intervals (RIs) for Hemoglobin A1C and other hemoglobin subfractions (A1A, A1B, F, LA1C, A0) is of utmost importance in screening, diagnosing, and monitoring diabetes and other hemoglobin abnormalities through the application of high-pressure liquid chromatography (HPLC) technique. Because there are no locally established RIs for these parameters, it is essential to establish RIs specific to the Saudi population to accurately diagnose and monitor diabetic individuals and identify abnormal levels in hemoglobin subfractions.

METHODS

As part of the IFCC global multicenter study of laboratory reference values, a cross-sectional study was conducted in Saudi Arabia. The study involved recruiting a total of 381 healthy adult subjects (>18 years, BMI 28.3 ± 6 kg/m2). Blood samples were analyzed for A1C, biochemical and other immunoassay parameters. The need for RIs based on sex, age, and BMI was determined using the standard deviation ratio (SDR) through a 3-level nested ANOVA.

RESULTS

Based on the threshold of SDR≥0.4, RIs for A1C and other Hb subfractions were not partitioned by sex or BMI, but partitioned by age (<45 & ≥45 years) for A1C, LA1C, A0 and F. Spearman's correlation between glucose, insulin, and C-peptide showed a positive association with different hemoglobin subtractions of A1B, F, A1C, and LA1C. The RIs were obtained by using the parametric method and the latent abnormal values exclusion (LAVE) principle was applied on A1C.

CONCLUSION

This study established RIs for A1C and other Hb subfractions for healthy adult Saudis. Age was found to be an important source of variation for most of the parameters including A1C. These findings will enhance the understanding and clinical decision-making concerning A1C and other hemoglobin subfractions. The elevated upper limit of RIs for A1C reflects the high prevalence of diabetes in the Saudi population specially in those with increased age.

Prevalence of prediabetes and risk of CVD mortality in individuals with prediabetes alone or plus hypertension in Northeast China: insight from a population based cohort study

BACKGROUND

To evaluate the current prevalence of prediabetes in northeast China, and further determine the association between prediabetes alone or coexistent with hypertension and cardiovascular disease (CVD) mortality.

METHODS

In the prospective study, 15,557 participants without diabetes among aged ≥40 years in northeast China, were followed for a median of 5.5 years. Following the American Diabetes Association, prediabetes was defined as fasting plasma glucose (FPG) range of 5.6-6.9 mmol/L or glycated hemoglobin (HbA1c) range of 5.7-6.4% in people without diabetes.

RESULTS

The prevalence of prediabetes was 44.3% among population aged ≥40 years in northeast China. Prediabetes alone did not promote risk of CVD mortality. However, when the subgroups were stratified by hypertension, the CVD mortality risk in prediabetes plus hypertension subjects increased significantly compared with population without prediabetes and hypertension. Multivariate-adjusted hazard ratios for CVD mortality in prediabetes subgroups plus hypertension were 2.28 (95% CI: 1.50, 3.47) for those diagnosed by FPG < 5.6 mmol/L & HbA1c 5.7-6.4%, 2.18 (95% CI: 1.53, 3.10) for those diagnosed by FPG 5.6-6.0 mmol/L & HbA1c < 6.5% and 2.35 (95% CI: 1.65, 3.35) for those diagnosed by FPG 6.1-6.9 & HbA1c < 6.5% compared with the reference group. Moreover, the percentage of hypertension in prediabetes subjects was high (60.4%), but the awareness, treatment and control rates were far from satisfactory (45.3, 35.1 and 4.8%, respectively).

CONCLUSIONS

The prevalence of prediabetes remains high in northeast China, and the CVD mortality was elevated significantly in prediabetes coexistent with hypertension. Considering the high percentage and low control rate of hypertension in prediabetes, strategies focused on HbA1c screening, FPG lowering and blood pressure management should be emphasized in northeast China.

A Prediction Model Based on Noninvasive Indicators to Predict the 8-Year Incidence of Type 2 Diabetes in Patients with Nonalcoholic Fatty Liver Disease: A Population-Based Retrospective Cohort Study

Background

The prevention of type 2 diabetes (T2D) and its associated complications has become a major priority of global public health. In addition, there is growing evidence that nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of diabetes. Therefore, the purpose of this study was to develop and validate a nomogram based on independent predictors to better assess the 8-year risk of T2D in Japanese patients with NAFLD.

Methods

This is a historical cohort study from a collection of databases that included 2741 Japanese participants with NAFLD without T2D at baseline. All participants were randomized to a training cohort (n = 2058) and a validation cohort (n = 683). The data of the training cohort were analyzed using the least absolute shrinkage and selection operator method to screen the suitable and effective risk factors for Japanese patients with NAFLD. A cox regression analysis was applied to build a nomogram incorporating the selected features. The C-index, receiver operating characteristic curve (ROC), calibration plot, decision curve analysis, and Kaplan-Meier analysis were used to validate the discrimination, calibration, and clinical usefulness of the model. The results were reevaluated by internal validation in the validation cohort.

Results

We developed a simple nomogram that predicts the risk of T2D for Japanese patients with NAFLD by using the parameters of smoking status, waist circumference, hemoglobin A1c, and fasting blood glucose. For the prediction model, the C-index of training cohort and validation cohort was 0.839 (95% confidence interval (CI), 0.804-0.874) and 0.822 (95% CI, 0.777-0.868), respectively. The pooled area under the ROC of 8-year T2D risk in the training cohort and validation cohort was 0.811 and 0.805, respectively. The calibration curve indicated a good agreement between the probability predicted by the nomogram and the actual probability. The decision curve analysis demonstrated that the nomogram was clinically useful.

Conclusions

We developed and validated a nomogram for the 8-year risk of incident T2D among Japanese patients with NAFLD. Our nomogram can effectively predict the 8-year incidence of T2D in Japanese patients with NAFLD and helps to identify people at high risk of T2D early, thus contributing to effective prevention programs for T2D.

The Compatibility of Hemoglobin A1c with Oral Glucose Tolerance Test and Fasting Plasma Glucose

Objectives:

Diabetes mellitus (DM) is a chronic metabolic disease requiring lifelong medical care, and its prevalence is increasing worldwide. Early diagnosis of prediabetes and diabetes is significant in view of the mortality, morbidity and cost associated with them. Because of the difficulties in application and reproducibility of oral glucose tolerance test (OGTT), which is considered to be the gold standard in the diagnosis of DM, more feasible diagnostic tests are needed. This study aims to evaluate the validity of hemoglobin A1c (HbA1c) in predicting prediabetes and diabetes in the Turkish population and to evaluate the compatibility of HbA1c with other diagnostic tests.

Methods:

The patients who were admitted to Health Sciences University Sisli Hamidiye Etfal Training and Research Hospital internal diseases and endocrinology outpatient clinics between 01.01.2013 and 30.06.2014 enrolled in this study. The participants were >18 years of age and were not diagnosed with prediabetes or DM earlier. The results of OGTT, fasting plasma glucose (FPG) and HbA1c tests were retrospectively screened, and the correlation of them was analyzed.

Results:

In this study, 201 participants enrolled. Of these cases, 127 were women and 74 were men. Mean age of the group was 49.3±10.4 years. HbA1c was observed <5.7% in the 15%, 5.7-6.4% in the 60%, and ≥ 6.5% in the 25% of the cases. While FPG was <100 mg/dL in 24% of the participants, it was found to be between 100-126 mg/dL in 71% and ≥126 mg/dL in 5% of the participants. According to the OGTT data, 23% of the cases were healthy, 59% were prediabetic and 18% were diabetic. The sensitivity and specificity of HbA1c were calculated as 50% and 80%, respectively. While the sensitivity of FPG was 17% and specificity was 97%.

Conclusion:

The data obtained from our study show that HbA1c is a more sensitive test compared to FPG in the diagnosis of DM. Prospective studies with broad participation at national and international levels are needed to redefine HbA1c cut-off points for the diagnosis of DM and prediabetes. Thus, it will be possible to revise the diagnostic guidelines accordingly.

Prevalence of type 2 diabetes and prediabetes in the Faroe Islands

AIMS

To determine the prevalence of type 2 diabetes mellitus and prediabetes among the population aged 40-74 years in the Faroe Islands.

METHODS

This population-based cross-sectional survey, conducted between 2011 and 2012, invited 2186 randomly selected individuals (corresponding to 11.1% of the entire population aged 40-74 years). Subjects were screened using finger capillary blood for glycosylated hemoglobin, type A1c, non-fasting random plasma glucose, fasting plasma glucose followed by oral glucose tolerance test. The test was based on an algorithm that accounts for screening, diagnostic and confirmatory steps. Anthropometric measures and a questionnaire including medical history, medication, hereditary conditions, and food intake were included.

RESULTS

The study included 1772 participants. Of the 1772, 169 (9.5%) had type 2 diabetes mellitus (3.0% of which were diagnosed upon study inclusion), thus 31.4% of subjects with diabetes were undiagnosed at the time of examination. A total of 271 (15.3%) had prediabetes. Diabetes was more prevalent among men, significantly from age ≥60 years. Women had lower mean fasting plasma glucose concentrations and men had lower values for 2-h plasma glucose. Predictors associated with diabetes mellitus included obesity (BMI ≥ 30), abnormal waist/hip ratio, history of hypertension or cardiovascular attack and family history of diabetes mellitus and leisure activity.

CONCLUSIONS

The prevalences of diabetes and prediabetes increased with age and were more frequent among men. The detected prevalence in the Faroe Islands was slightly higher than other Nordic countries.

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.

Incidence Rate of Prediabetes Progression to Diabetes: Modeling an Optimum Target Group for Intervention

Thirty-seven percent of US adults have prediabetes. Various interventions can delay diabetes progression; however, the optimum target group for risk reduction is uncertain. This study estimated rate of progression to diabetes at 1 and 5 years among a cohort of patients from 3 primary care clinics and modeled the potential magnitude in diabetes incidence risk reduction of an intervention program among specific subgroups. Records of 106,821 empaneled patients in 2005 were reviewed. Generalized population attributable risk (PAR) statistics were calculated to estimate the impact of reducing fasting blood glucose on diabetes progression. Multiple intervention effects (varying levels of glucose reduction along with multiple adherence rates) were examined for those with baseline glucose from 110 to 119 mg/dL and ≥120 mg/dL. Ten percent of patients (n = 10,796) met criteria for prediabetes. The 1- and 5-year diabetes incidence rate was 38.6 and 40.24 per 1000 person-years, respectively. Age and obesity were independent predictors of increased progression rate. The generalized PAR for a 10-point reduction in the 110-119 mg/dL subgroup with 25% adherence was 7.6%. The generalized PAR for similar percent reduction and adherence level in patients with baseline glucose of ≥120 mg/dL was only 3.0%. Rate of progression to diabetes increased over time and with associated independent risk factors. Greater risk reduction in diabetes progression within the target population can be achieved when the intervention is successful in those with baseline glucose of 110-119 mg/dL. Modeling an optimum target group for a diabetes prevention intervention offers a novel and useful guide to planning and allocating resources in population health management.

A novel model enhances HbA1c-based diabetes screening using simple anthropometric, anamnestic, and demographic information

BACKGROUND

The sensitivity of HbA1c is not optimal for the screening of patients with latent diabetes. We hypothesize that simple healthcare information could improve accuracy.

METHODS

We retrospectively analyzed data, including HbA1c, from multiple years from the National Health and Nutrition Examination Survey (NHANES) database (2005-2010). The data were used to create a logistic regression classification model for screening purposes.

RESULTS

The study evaluated data for 5381 participants, including 404 with undiagnosed diabetes. The HbA1c screening data were supplemented with information about age, waist circumference, and physical activity in the HbA1c+ model. Alone, HbA1c alone had a receiver operating characteristics (ROC) curve for the area under the curve (AUC) of 0.808 (95% confidence interval [CI] 0.792-0.834). The HbA1c+ model had an ROC AUC of 0.851 (95% CI 0.843-0.872). There was a significant difference in the AUC between our model and using HbA1c without supplementary information (P < 0.05).

CONCLUSIONS

We have developed a novel screening model that could help improve screening for type 2 diabetes with HbA1c. It seems beneficial to systematically add additional patient healthcare information in the process of screening with HbA1c.

The metabolic deterioration that antedates diabetes: personal trajectories of HbA(1c) and fasting glucose as early indicators and possible triggers for intervention

HbA(1c) testing has become an accepted means of diagnosing diabetes as an alternative to blood glucose levels. However, population-based norms of glucose and of HbA(1c) levels do not enable the detection of diabetes at an early enough stage to thwart complications. Personal trajectories of glucose levels show steep increases a number of years prior to diabetes diagnosis. Here, we hypothesize that a comparable time-dependent deviation in an individual's HbA(1c) level may be an early manifestation of disease that should prompt lifestyle modifications. We predict that analysis of personal trajectories of glucose and of HbA(1c) will promote earlier intervention and a greater reduction in disease complications than current standards, which are based on population-based norms.