A1C: recommendations, debates, and questions

Ocular pharmacological and biochemical profiles of 6-thioguanine: a drug repurposing study

Introduction

The purine analog 6-thioguanine (6TG), an old drug approved in the 60s to treat acute myeloid leukemia (AML), was tested in the diabetic retinopathy (DR) experimental in vivo setting along with a molecular modeling approach.

Methods

A computational analysis was performed to investigate the interaction of 6TG with MC1R and MC5R. This was confirmed in human umbilical vein endothelial cells (HUVECs) exposed to high glucose (25 mM) for 24 h. Cell viability in HUVECs exposed to high glucose and treated with 6TG (0.05-0.5-5 µM) was performed. To assess tube formation, HUVECs were treated for 24 h with 6TG 5 µM and AGRP (0.5-1-5 µM) or PG20N (0.5-1-5-10 µM), which are MC1R and MC5R antagonists, respectively. For the in vivo DR setting, diabetes was induced in C57BL/6J mice through a single streptozotocin (STZ) injection. After 2, 6, and 10 weeks, diabetic and control mice received 6TG intravitreally (0.5-1-2.5 mg/kg) alone or in combination with AGRP or PG20N. Fluorescein angiography (FA) was performed after 4 and 14 weeks after the onset of diabetes. After 14 weeks, mice were euthanized, and immunohistochemical analysis was performed to assess retinal levels of CD34, a marker of endothelial progenitor cell formation during neo-angiogenesis.

Results

The computational analysis evidenced a more stable binding of 6TG binding at MC5R than MC1R. This was confirmed by the tube formation assay in HUVECs exposed to high glucose. Indeed, the anti-angiogenic activity of 6TG was eradicated by a higher dose of the MC5R antagonist PG20N (10 µM) compared to the MC1R antagonist AGRP (5 µM). The retinal anti-angiogenic effect of 6TG was evident also in diabetic mice, showing a reduction in retinal vascular alterations by FA analysis. This effect was not observed in diabetic mice receiving 6TG in combination with AGRP or PG20N. Accordingly, retinal CD34 staining was reduced in diabetic mice treated with 6TG. Conversely, it was not decreased in diabetic mice receiving 6TG combined with AGRP or PG20N.

Conclusion

6TG evidenced a marked anti-angiogenic activity in HUVECs exposed to high glucose and in mice with DR. This seems to be mediated by MC1R and MC5R retinal receptors.

A Mutagen Acts as a Potent Reducing Agent of Glycated Hemoglobin: a Combined Ultrafast Electron Transfer and Computational Studies

Glycated hemoglobin (GHb) found in mammals undergoes irreversible damage when exposed to external redox agents, which is much more vulnerable than its normal counterpart hemoglobin (Hb). Besides the oxygen regulation throughout the body, Hb plays a vital role in balancing immunological health and the redox cycle. Photoinduced ultra-fast electron transfer phenomena actively participate in regulation of various kind of homeostasis involved in such biomacromolecules. In the present study we have shown that a well-known mutagen Ethidium Bromide (EtBr) reduces GHb in femtosecond time scale (efficiently) upon photoexcitation after efficient recognition in the biomolecule. We have performed similar experiment by colocalizing EtBr and Iron (Fe(III)) on the micellar surface as Hb mimic in order to study the excited state EtBr dynamics to rationalize the time scale obtained from EtBr in GHb and Hb. While other experimental techniques including Dynamic Light Scattering (DLS), Zeta potential, absorbance and emission spectroscopy have been employed for the confirmation of structural perturbation of GHb compared to Hb, a detailed computational studies involving molecular docking and density functional theory (DFT) have been employed for the explanation of the experimental observations.

Optimal fasting plasma glucose and haemoglobin A1c levels for screening of prediabetes and diabetes according to 2-hour plasma glucose in a high-risk population: The Korean Diabetes Prevention Study

BACKGROUND

The primary aim of this study was to assess the utility of fasting plasma glucose (FPG) and HbA1c to identify diabetes by the 2-hour plasma glucose (PG) criterion in the Korean population at high risk for diabetes.

METHODS

A total of 1646 participants with a body mass index of ≥23 kg/m2 without having a history of diabetes were recruited in this study. The cut-off values of FPG and HbA1c for detecting diabetes were identified using the Youden index using receiver operating characteristic (ROC) analysis. The gold standard for diabetes prediction was defined by the 2-hour PG level of ≥200 mg/dL.

RESULTS

The participants comprised 54.0% women, and the mean age of all participants was 55.0 ± 8.1 years. At baseline, FPG was 104.1 ± 14.2 mg/dL, the 2-hour PG value was 162.9 ± 55.3 mg/dL, and HbA1c was 5.9% ± 0.5%. Four hundred and forty-six subjects (27.1%) were diagnosed with diabetes and 976 subjects (59.3%) were determined to be at prediabetes. The area under the ROC curve (AUC) of FPG and HbA1c for diabetes were 0.776 and 0.802, while the AUC of FPG and HbA1c for prediabetes were 0.515 and 0.477. The optimal cut-off value for diagnosing diabetes of FPG and HbA1c were 104.5 mg/dL (sensitivity 75.8%, specificity 67.5%) and 5.9% (sensitivity 80.6%, specificity 63.8%), respectively.

CONCLUSIONS

FPG of 104.5 mg/dL and HbA1c value of 5.9% (41 mmol/mol) can be used as an optimal screening value for diabetes by 2-hour PG criterion in the Korean population at high risk for diabetes.

Increased Levels of Glycated Hemoglobin A1c and Iron Deficiency Anemia: A Review

Worldwide, the prevalence of diabetes remains high. Studies have shown that iron deficiency anemia (IDA) is associated with increased levels of glycated hemoglobin A1c (HbA1c), but the mechanism remains unclear. Hematological changes, iron metabolism, study methodology, and other factors could affect the results of diagnostic investigations, leading to false results. Red blood cell turnover in the bone marrow and the quality and heterogeneity of erythrocytes may influence the rate of hemoglobin glycation. By changing the structure of hemoglobin and inducing peroxidation, iron deficiency accelerates glycation. This review aims to discuss the possible causes of the association between increased levels of HbA1c and IDA.

Discrepancies between Glycosylated Hemoglobin and Fasting Plasma Glucose for Diagnosing Impaired Fasting Glucose and Diabetes Mellitus in Korean Youth and Young Adults

BACKGROUND

Glycosylated hemoglobin (HbA1c) has been recommended as a diagnostic test for prediabetes and diabetes. Here, we evaluated the level of agreement between diagnoses based on fasting plasma glucose (FPG) versus HbA1c levels and determined optimal HbA1c cutoff values for these diseases in youth and young adults.

METHODS

The study included 7,332 subjects (n=4,129, aged 10 to 19 years in youth group; and n=3,203 aged 20 to 29 years in young adult group) from the 2011 to 2016 Korea National Health and Nutrition Examination Survey. Prediabetes and diabetes were defined as 100 to 125 mg/dL (impaired fasting glucose [IFG]) and ≥126 mg/dL for FPG (diabetes mellitus [DM] by FPG [DM_FPG]), and 5.7% to 6.4% and ≥6.5% for HbA1c, respectively.

RESULTS

In the youth group, 32.5% with IFG had an HbA1c level of 5.7% to 6.4%, and 72.2% with DM_FPG had an HbA1c ≥6.5%. In the young adult group, 27.5% with IFG had an HbA1c level of 5.7% to 6.4%, and 66.6% with DM_FPG had an HbA1c ≥6.5%. Kappa coefficients for agreement between the FPG and HbA1c results were 0.12 for the youth group and 0.19 for the young adult group. In receiver operating characteristic curve analysis, the optimal HbA1c cutoff for IFG and DM_FPG were 5.6% and 5.9% in youths and 5.5% and 5.8% in young adults, respectively.

CONCLUSION

Usefulness of HbA1c for diagnosis of IFG and DM_FPG in Koreans aged <30 years remains to be determined due to discrepancies between the results of glucose- and HbA1c-based tests. Additional testing might be warranted at lower HbA1c levels to detect IFG and DM_FPG in this age group.

Activation of cancer-related and mitogen-activated protein kinase signaling pathways in human mature osteoblasts isolated from patients with type 2 diabetes

Diabetes mellitus is a disease of glucose metabolism, and it adversely affects bone metabolism and increases the risk of cancer development. Previously, we reported a method for the direct isolation of human mature osteoblasts and indicated that osteoblasts were associated with type 2 diabetes mellitus-related signaling pathways. In addition, a recent report suggested that osteoblasts are involved in glucose metabolism. Thus, we sought to examine the effects of diabetes on osteoblast signaling in vivo. We recruited eight patients with type 2 diabetes and eight non-diabetic individuals. We isolated human mature osteoblasts from the resected femoral heads during orthopaedic surgery and extracted their RNA. We compared the gene expression between the two groups by RNA microarray and pathway analyses. Microarray analysis showed significant differences in 885 of 19,463 genes between the two groups (p < 0.05), and pathway analysis revealed that pathways related to cancer and the mitogen-activated protein kinase signaling pathway were significantly activated in the diabetes group (p < 0.01). These preliminary findings suggest that diabetes affects intracellular signaling in human mature osteoblasts and that osteoblasts might not only play a key role in the regulation of bone and glucose metabolism, but might also be related to cancer metabolism. We plan to conduct further studies to examine signaling in diabetic osteoblasts and to further investigate the genes and pathways identified here.

•

Compared microarray data from in vivo DM and healthy control osteoblasts

•

MAPK and cancer-related signaling genes were enriched in DM osteoblasts.

•

DM may increase cancer risk by activating cancer-related pathways in osteoblasts.

Plasma glucose and hemoglobin A1c for the detection of diabetes in Chinese adults

BACKGROUND

The aim of the present study was to evaluate the performance of plasma glucose (PG) and HbA1c for the detection of diabetes in the general population in China.

METHODS

A cross-sectional analysis was conducted in a nationally representative sample of 98,658 Chinese adults aged ≥18 years. Fasting plasma glucose and HbA1c levels were measured in all participants after at least a 10-h overnight fast. An oral glucose tolerance test (OGTT) was conducted among participants without a self-reported history of diagnosed diabetes.

RESULTS

An HbA1c ≥6.5% could identify 4.57% of Chinese adults as having newly detected diabetes, followed by fasting PG (FPG) and 2-h PG at 4.52% and 3.50%, respectively. Approximately 1.95% of the total population was detected by HbA1c but not by FPG or 2-h PG. However, FPG plus HbA1c could identify most (85.2%) diabetic individuals identified by any of the three tests (i.e., FPG, 2-h PG, and HbA1c). Levels of most cardiovascular risk factors, such as body mass index, waist circumference, and cholesterol, were higher in diabetes detected by HbA1c alone than in diabetes identified by the OGTT.

CONCLUSIONS

Although HbA1c ≥6.5% has been recommended by the American Diabetes Association as one of the diagnostic tests for diabetes, caution should be used to avoid potential overdiagnosis when interpreting diabetes identified by elevated HbA1c alone.

Correlation of fasting and postprandial plasma glucose with HbA1c in assessing glycemic control; systematic review and meta-analysis

BACKGROUND

Glycemic control in diabetes mellitus is a cornerstone in reducing morbidity and mortality of the disease. Achieving glycemic control or reducing hyperglycemia significantly decreases the microvascular and macrovascular complications of diabetes. Even though measurement of glycated hemoglobin (HbA1c) remains the gold standard for assessment of glycemic control, there is no consensus whether fasting or postprandial plasma glucose (PPG) is a better predictor of glycemic control in resource-poor settings when HbA1c is not available. The aim of this systematic review and meta-analysis was to summarize evidences on the significance of fasting and postprandial plasma glucose, and their correlation with HbA1c.

METHODS

Relevant studies were identified through systematic search of online databases (e.g. EMBASE, MEDLINE/PubMed and Cochrane library) and manual search of bibliographies of the included studies. Original research papers describing the correlations or associations of fasting and postprandial plasma glucose with HbA1c were included. The MedCalc software was used for data entry and analysis. We used the random effect model to estimate the pooled correlations of fasting and postprandial plasma glucose with HbA1c. Heterogeneity assessment and robustness analysis was also performed.

RESULT

From total 126 articles identified, 14 articles were eligible for systemic review. Eleven of these eligible studies evaluated the correlations of fasting and postprandial plasma glucose to the standard HbA1c values and used in meta-analysis. Seven of these studies (63.5 %) found better or stronger correlations between PPG and HbA1c than fasting plasma glucose (FPG). In all the studies that estimated the relative contribution FPG and PPG to the overall hyperglycemia, decreases in PPG was accounted for greater decrease in HbA1c compared with decreases in FPG value. PPG also showed a better sensitivity, specificity and positive predictive value than FPG. The pooled correlation coefficient (r) between PPG and HbA1c was 0.68 (P < 0.001, 95 % CI; 0.56-0.75) slightly higher than pooled correlation coefficient of FPG (r = 0.61(P < 0.001, 95 % CI; 0.48-0.72)).

CONCLUSION

PPG has a closer association with HbA1c than FPG. Hence, PPG is better in predicting overall glycemic control in the absence of HbA1c.

Glycated Hemoglobin Level and Mortality in a Nondiabetic Population with CKD

BACKGROUND AND OBJECTIVES

Glycated hemoglobin (HbA1c) is used to diagnose diabetes mellitus (DM) and guide its management. The association between higher HbA1c and progression to ESRD and mortality has been demonstrated in populations with DM. This study examined the association between HbA1c and these end points in a population with CKD and without DM.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In the hospital-based NephroTest cohort study, measured GFR (mGFR) was taken by (51)Cr-EDTA renal clearance and HbA1c in 1165 adults with nondialysis CKD stages 1-5 and without DM between January 2000 and December 2010. The median follow-up was 3.48 years (interquartile range, 1.94-5.82) for the competing events of ESRD and pre-ESRD mortality. Time-fixed and time-dependent Cox models were used to estimate hazard ratios (HRs) for ESRD and mortality according to HbA1c, treated continuously or in tertiles.

RESULTS

At inclusion, the mean mGFR was 42.2±19.9 ml/min per 1.73 m(2), and the mean HbA1c value was 5.5%±0.5%. During follow-up, 109 patients died, and 162 patients reached ESRD. Pre-ESRD mortality was significantly associated with HbA1c treated continuously: for every 1% higher HbA1c, the crude HR was 2.16 (95% confidence interval [95% CI], 1.27 to 3.68), and it was 1.85 (95% CI, 1.05 to 3.24) after adjustment for mGFR and other risk factors of death. After excluding incident diabetes over time, the updated mean of HbA1c remained significantly associated with higher mortality risk: adjusted HR for the highest (5.7%-6.4%) versus the lowest tertile (<5.3%) was 2.62 (95% CI, 1.16 to 5.91). There was no association with ESRD risk after adjustment for risk factors of CKD progression.

CONCLUSIONS

In a CKD cohort, HbA1c values in the prediabetes range are associated with mortality. Such values should be therefore included among the risk factors for negative outcomes in CKD populations.

Prediabetes: The Variation between HbA1c and Fasting Plasma Glucose

PURPOSE

The prevalence of Diabetes Type 2 is on the rise internationally. Currently, Fasting Plasma Glucose (FPG) and HbA1c are both used to determine if an individual is diabetic or prediabetic. We aimed to describe the prevalence of diabetes, prediabetes, and glycemic control in a population-based sample of elderly Hispanic and non-Hispanic White participants in New Mexico.

METHODS

To do this, we compared HbA1c with FPG using Chi-Square analysis across gender and ethnicity to provide information for future health care policy. We also performed non-parametric regression using a locally weighted smoothing technique to investigate the relationship between FPG and HbA1c levels.

RESULTS

Our analysis identifies a large variation between the sensitivity of HbA1c and FPG in the identification of both prediabetes and diabetes. Interestingly, 95% of diabetics defined by FPG are also defined by HbA1c, representing overlap between the two measures. When comparing the prevalence of prediabetes between the two measures, the overlap of FPG with HbA1c was only 30% and HbA1c identifies more individuals as prediabetic than FPG. Prevalence of diabetes was also higher when defined by HbA1c compared to FPG and the overall agreement between HbA1c and FPG appears to be poor particularly by sex and ethnicity (K=0.22-0.34). Glycemic control was poor overall with Hispanics displaying a larger amount of uncontrolled diabetes.

CONCLUSION

We compared HbA1c and FPG by gender and ethnicity and showed both measures of diabetes differ in their sensitivity across ethnic groups. Our results suggest that using HbA1c, rather than FPG, results in higher rates of prediabetes and diabetes, a finding with numerous implications for health care practice.

Misleading hemoglobin A1c levels in a patient with paroxysmal nocturnal hemoglobinuria

OBJECTIVES

We report a case of a patient with diabetes mellitus and unexpectedly low hemoglobin A1c results associated with paroxysmal nocturnal hemoglobinuria (PNH). We review the impact of shortened RBC half-life on the interpretation of hemoglobin A1c levels.

METHODS

Patient history and laboratory test results were obtained from electronic medical records and analyzed.

RESULTS

The patient's hemoglobin A1c declined in parallel to worsening anemia after the diagnosis of PNH. However, elevated serum glucose (random), fructosamine, and glycated albumin suggest ongoing hyperglycemia. Together, these results argue that the decline in hemoglobin A1c was due to decreased RBC survival secondary to PNH.

CONCLUSIONS

Hemoglobin A1c levels must be interpreted with caution in patients with hematologic diseases that change RBC survival. Serum fructosamine and glycated albumin measurements are alternative measures of time-averaged blood glucose control and may be useful in this subset of patients.

No racial differences in the association of glycated hemoglobin with kidney disease and cardiovascular outcomes

OBJECTIVE

There is debate regarding the clinical significance of well-established racial differences in HbA1c. We compared the associations of diabetes diagnostic categories for HbA1c and fasting glucose with clinical outcomes in black and white persons in the community.

RESEARCH DESIGN AND METHODS

We conducted a prospective cohort analysis of participants without diabetes or cardiovascular disease from the Atherosclerosis Risk in Communities study. We examined the associations of clinical categories of HbA1c (<5.7%, 5.7-6.4%, ≥6.5%) and fasting glucose (<100, 100-125, ≥126 mg/dL) with outcomes separately among 2,484 black and 8,593 white participants and tested for race interactions.

RESULTS

Baseline characteristics differed significantly in blacks compared with whites, including HbA1c (5.8 vs. 5.4%; P<0.001). During 18 years of follow-up, there were trends of increased risk of kidney disease, fatal and nonfatal coronary heart disease, and stroke across categories of HbA1c in both blacks and whites. The adjusted hazard ratios for each outcome across categories of HbA1c were similar in blacks and whites (P for interaction>0.05) except for all-cause mortality. Patterns of association were similar, but weaker, for fasting glucose. HbA1c and fasting glucose both were more strongly associated with all-cause mortality in whites compared with blacks, largely explained by racial differences in the rate of cardiovascular deaths.

CONCLUSIONS

HbA1c is a risk factor for vascular outcomes and mortality in both black and white adults. Patterns of association for HbA1c were similar to or stronger than those for fasting glucose. With respect to long-term outcomes, our findings support a similar interpretation of HbA1c in blacks and whites for diagnosis and treatment of diabetes mellitus.

Association of HbA1c with emotion regulation, intolerance of uncertainty, and purpose in life in type 2 diabetes mellitus

BACKGROUND

The extant literature lacks breadth on psychological variables associated with health outcome for type 2 diabetes mellitus (T2DM). This investigation extends the scope of psychological information by reporting on previously unpublished factors.

OBJECTIVE

To investigate if intolerance of uncertainty, emotion regulation, or purpose in life differentiate T2DM adults with sustained high HbA(1c) (HH) vs. sustained acceptable HbA(1c) (AH).

SUBJECTS AND METHODS

Cross-sectional observational study. Adult patients with diagnosed T2DM meeting inclusionary criteria for AH, HH, or a nondiabetic reference group (NDR) were randomly selected and invited to participate. Patients who consented and participated resulted in a final sample of 312 subgrouped as follows: HH (n = 108); AH (n = 98); and NDR (n = 106). Data sources included a survey, self-report questionnaires, and electronic medical record (EMR).

RESULTS

HH individuals with T2DM reported lower purpose in life satisfaction (p = 0.005) compared to the NDR group. The effect size for this finding is in the small-to-medium range using Cohen's guidelines for estimating clinical relevance. The HH-AH comparison on purpose in life was nonsignificant. The emotion regulation and intolerance of uncertainty comparisons across the three groups were not significant.

CONCLUSIONS

The present study determined that lower purpose in life satisfaction is associated with higher HbA(1c). In a T2DM patient with sustained high HbA(1c), the primary care clinician is encouraged to consider screening for purpose in life satisfaction by asking a single question such as "Do the things you do in your life seem important and worthwhile?" The patient's response will assist the clinician in determining if meaning or purpose in life distress may be interferring with diabetes self-care. If this is the case, the clinician can shift the conversation to the value of behavioral and emotional health counseling.

Variables involved in the discordance between HbA1c and fructosamine: the glycation gap revisited

AIMS

Glycation gap (GG) is defined as the difference between the measured level of HbA1c and the level that would be predicted from its regression on the fructosamine level. The aims of the study were: 1) To determine the reproducibility and consistency of GC; 2) To discover factors related to GG value. Given that metformin might increase glucose transport through the erythrocyte membrane, this treatment was also considered in the analyses of the results.

METHODS

GG was calculated in two blood samples separated 30.6 (SD 7.3) weeks, obtained in 508 type 2 diabetic patients. The following variables were considered: HbA1c, fructosamine, glucose, creatinine, hematological parameters and treatment with metformin. Multivariate and logistic regression analyses were performed to explore the variables independently related to CG.

RESULTS

GG was reproducible and consistent over time. Creatinine, mean corpuscular hemoglobin concentration (MCHC), and glycemia (inverse relationship); and HbA1c and treatment with metformin (direct relationship) were independently related to GG. Patients treated with metformin showed higher HbA1c values, despite similar fructosamine concentrations, than patients not treated with the drug.

CONCLUSIONS

GG is independently related to serum levels of creatinine, MCHC and treatment with metformin. The spurious effect of metformin on Hb glycation could have serious clinical implications and should be considered when interpreting the results of clinical trials.

No ethnic differences in the association of glycated hemoglobin with retinopathy: the national health and nutrition examination survey 2005-2008

OBJECTIVE

Current recommendations for the use of hemoglobin A(1c) (HbA(1c)) in diabetes screening and diagnosis aim to identify those at greatest risk for diabetic microvascular complications. However, there is current controversy regarding the clinical implications of ethnic differences in HbA(1c) values. The objective of this study was to determine whether the association between HbA(1c) and retinopathy differs by ethnic group in a representative sample of U.S. adults.

RESEARCH DESIGN AND METHODS

The study was a cross-sectional analysis of 2,945 non-Hispanic white, 1,046 non-Hispanic black, and 1,231 Hispanic American participants aged ≥40 years from the 2005-2008 National Health and Nutrition Examination Survey.

RESULTS

Among nondiabetic adults, the mean HbA(1c) was 5.5% in non-Hispanic whites, 5.7% in non-Hispanic blacks, and 5.6% in Hispanic Americans. Among those with diagnosed diabetes, mean HbA(1c) was 6.9% in non-Hispanic whites, 7.5% in non-Hispanic Blacks, and 7.7% in Hispanic Americans. Overall, non-Hispanic blacks had the highest prevalence of retinopathy. In multivariable logistic models, HbA(1c) clinical categories were strongly associated with prevalent retinopathy. However, the magnitude of the association did not differ by ethnic group (all P values for interaction ≥ 0.7). Similar results were observed with HbA(1c) modeled continuously (per one percentage point) and stratified by diabetes status (all P for interactions > 0.3).

CONCLUSIONS

We observed no ethnic differences in the association of HbA(1c) with retinopathy. These data do not support ethnic-specific cut points for HbA(1c) for diagnosis or screening of diabetes mellitus.

Shifting from glucose diagnosis to the new HbA1c diagnosis reduces the capability of the Finnish Diabetes Risk Score (FINDRISC) to screen for glucose abnormalities within a real-life primary healthcare preventive strategy

BACKGROUND

To investigate differences in the performance of the Finnish Diabetes Risk Score (FINDRISC) as a screening tool for glucose abnormalities after shifting from glucose-based diagnostic criteria to the proposed new hemoglobin (Hb)A1c-based criteria.

METHODS

A cross-sectional primary-care study was conducted as the first part of an active real-life lifestyle intervention to prevent type 2 diabetes within a high-risk Spanish Mediterranean population. Individuals without diabetes aged 45-75 years (n = 3,120) were screened using the FINDRISC. Where feasible, a subsequent 2-hour oral glucose tolerance test and HbA1c test were also carried out (n = 1,712). The performance of the risk score was calculated by applying the area under the curve (AUC) for the receiver operating characteristic, using three sets of criteria (2-hour glucose, fasting glucose, HbA1c) and three diagnostic categories (normal, pre-diabetes, diabetes).

RESULTS

Defining diabetes by a single HbA1c measurement resulted in a significantly lower diabetes prevalence (3.6%) compared with diabetes defined by 2-hour plasma glucose (9.2%), but was not significantly lower than that obtained using fasting plasma glucose (3.1%). The FINDRISC at a cut-off of 14 had a reasonably high ability to predict diabetes using the diagnostic criteria of 2-hour or fasting glucose (AUC = 0.71) or all glucose abnormalities (AUC = 0.67 and 0.69, respectively). When HbA1c was used as the primary diagnostic criterion, the AUC for diabetes detection dropped to 0.67 (5.6% reduction in comparison with either 2-hour or fasting glucose) and fell to 0.55 for detection of all glucose abnormalities (17.9% and 20.3% reduction, respectively), with a relevant decrease in sensitivity of the risk score.

CONCLUSIONS

A shift from glucose-based diagnosis to HbA1c-based diagnosis substantially reduces the ability of the FINDRISC to screen for glucose abnormalities when applied in this real-life primary-care preventive strategy.

Performance of a multi-marker diabetes risk score in the Insulin Resistance Atherosclerosis Study (IRAS), a multi-ethnic US cohort

BACKGROUND

This study compares a previously developed Diabetes Risk Score to commonly used clinical tools for type 2 diabetes risk evaluation in the Insulin Resistance Atherosclerosis Study (IRAS) cohort, a multi-ethnic US cohort. Available as a clinical test, the PreDx® Diabetes Risk Score uses fasting concentrations of adiponectin, C-reactive protein, ferritin, interleukin-2 receptor alpha, HbA(1c) , glucose and insulin, plus age and gender to predict 5-year risk of diabetes. It was developed in a Northern European population.

METHODS

The Diabetes Risk Score was measured using archived fasting plasma specimens from 722 non-diabetic IRAS participants, 17.6% of whom developed diabetes during 5.2 years median follow-up (inter-quartile range: 5.1-5.4 years). The study included non-Hispanic whites (41.8%), Hispanics (34.5%) and African Americans (23.7%). Performance of the algorithm was evaluated by area under the receiver operating characteristic curve (AROC) and risk reclassification against other tools.

RESULTS

The Diabetes Risk Score discriminates participants who developed diabetes from those who did not significantly better than fasting glucose (AROC = 0.763 versus 0.710, p = 0.003). The Diabetes Risk Score performed equally well in subpopulations defined by race/ethnicity or gender. The Diabetes Risk Score provided a significant net reclassification improvement of 0.24 (p = 0.01) when comparing predefined low/moderate/high Diabetes Risk Score categories to metabolic syndrome risk factor counting. The Diabetes Risk Score complemented the use of the oral glucose tolerance test by identifying high risk patients with impaired fasting glucose but normal glucose tolerance, 33% of whom converted.

CONCLUSIONS

Measuring the Diabetes Risk Score of elevated-risk US patients could help physicians decide which patients warrant more intensive intervention. The Diabetes Risk Score performed equally well across the ethnic subpopulations present in this cohort.

Alternative HbA1c cutoffs to identify high-risk adults for diabetes prevention: a cost-effectiveness perspective

BACKGROUND

New recommendations about the use of hemoglobin A1c (HbA1c) for diagnosing diabetes have stimulated a debate about the optimal HbA1c cutoff to identify prediabetes for preventive intervention.

PURPOSE

To assess the cost effectiveness associated with the alternative HbA1c cutoffs for identifying prediabetes.

METHODS

A Markov simulation model was used to examine the cost effectiveness associated with a progressive 0.1% decrease in the HbA1c cutoff from 6.4% to 5.5%. The target population was the U.S. nondiabetic population aged ≥18 years. The simulation sample was created using the data of nondiabetic American adults from the National Health and Nutritional Examination Survey (NHANES 1999-2006). People identified as having prediabetes were assumed to receive a preventive intervention, with effectiveness the same as that in the Diabetes Prevention Program study under a high-cost intervention (HCI) scenario and in the Promoting a Lifestyle of Activity and Nutrition for Working to Alter the Risk of Diabetes study under a low-cost intervention (LCI) scenario. The analysis was conducted for a lifetime horizon from a healthcare system perspective.

RESULTS

Lowering the HbA1c cutoff would increase the health benefits of the preventive interventions at higher costs. For the HCI, lowering the HbA1c cutoff from 6.0% to 5.9% and from 5.9% to 5.8% would result in $27,000 and $34,000 per QALY gained, respectively. Continuing to decrease the cutoff from 5.8% to 5.7%, from 5.7% to 5.6%, and from 5.6% to 5.5% would cost $45,000, $58,000, and $96,000 per QALY gained, respectively. For the LCI, lowering the HbA1c cutoff from 6.0% to 5.9% and from 5.9% to 5.8% would result in $24,000 and $27,000 per QALY gained, respectively. Continuing to lower the cutoff from 5.8% to 5.7%, 5.7% to 5.6%, and 5.6% to 5.5% would cost $34,000, $43,000 and $70,000 per QALY gained, respectively.

CONCLUSIONS

Lowering the HbA1c cutoff for prediabetes leads to less cost-effective preventive interventions. Assuming a conventional $50,000/QALY cost-effectiveness benchmark, the HbA1c cutoffs of 5.7% and higher were found to be cost effective. Lowering the cutoff from 5.7% to 5.6% also may be cost effective, however, if the costs of preventive interventions were to be lowered.

Sensitivity of A1C to diagnose diabetes is decreased in high-risk older Southeast Asians

OBJECTIVE

To determine the effect of ageing on the performance of glycosylated haemoglobin A1C (A1C) for the diagnosis of diabetes mellitus (DM) in Southeast Asians.

METHODS

A1C was measured in 511 subjects (mean age of 52.4 years; range 14-93) undergoing the 75-g oral glucose tolerance test (OGTT). Using receiver operating curve (ROC) analysis, the performance of A1C for the diagnosis of diabetes (using different standard criteria) was compared between 4 groups: <45 (n=156), 45-54 (n=132), 55-64 (n=122), ≥65 years (n=101).

RESULTS

Subjects aged ≥65 years had the highest false-negative rates with fasting plasma glucose (60.8%) and A1C (35.1%), the smallest area under ROC curve (0.723, 95% CI 0.627-0.820), the lowest sensitivity (58.7%, 95% CI 50.4-65.7) and specificity (71.1%, 95% CI 57.3-82.6) of A1C 6.5%, compared to the younger age groups.

CONCLUSION

OGTT is preferable for diagnosis of DM in older Southeast Asian adults.

Glycated hemoglobin, diabetes mellitus, and cardiovascular risk in a cross-sectional study among She Chinese population

OBJECTIVE

To determine whether glycated hemoglobin (HbA1c) could be used to diagnose Type 2 diabetes mellitus in She Chinese People and to assess the role of HbA1c in the development of cardiovascular disease.

RESEARCH DESIGN AND METHODS

An ethnically representative sample of 687 (277 males and 410 females) adults, 20 yr of age or older participated in the study, and 75-g oral glucose tolerance test was administrated. Based on receiver operating characteristic curves, various cut-off values of HbA1c were used to stratify glucose tolerance. Several indexes were used to assess the cardiovascular risk, including estimated glomerular filtration rate (eGFR), Tpeak-end, Tp-e dispersion, aVL R wave, and QTc.

RESULTS

Using World Health Organization as gold standard, the HbA1c value of 6.9% was optimal to diagnose diabetes mellitus with a sensitivity of 35.3% and specificity of 94.0%. And for impaired fasting glucose, impaired glucose tolerance, and impaired glucose regulation, the cut-off points were all 6.1%. Assessed by logistic regression model, HbA1c was an independent risk factor for the decline in eGFR; R wave in lead aVL increased significantly (p<0.05) with the increase of HbA1c values. Other indexes reflecting the cardiovascular risks were not meaningful in our study.

CONCLUSIONS

HbA1c may be not a preferred method to diagnose Type2 diabetes in She Chinese people. However, more attention should be paid to subjects with HbA1c>6.1%, and their blood glucose should be tightly measured in clinical practice. In addition, we suggest that HbA1c is a predictor of cardiovascular disease.

Is there a relationship between mean blood glucose and glycated hemoglobin?

Measurement of hemoglobin A1c (HbA1c) is considered the gold standard for monitoring chronic glycemia of diabetes patients. Hemoglobin A1c indicates an average of blood glucose levels over the past 3 months. Its close association with the risk for the development of long-term complications is well established. However, HbA1c does not inform patients about blood glucose values on a daily basis; therefore, frequent measurements of blood glucose levels are necessary for the day-to-day management of diabetes. Clinicians understand what HbA1c means and how it relates to glucose, but this is not the case with patients. Therefore, the translation of the HbA1c results into something more familiar to patients seemed a necessity. The scope of this article is to review the literature to search for enough scientific evidence to support the idea of a close relationship between HbA1c and mean blood glucose (MBG), and to justify the translation of HbA1c into something that reflects the MBG. Most studies confirm a close relationship between HbA1c and MBG, although different studies result in different linear equations. Factors affecting this relationship may limit the usefulness and applicability of a unique mathematical equation to all diabetes populations.

Shifting from glucose diagnostic criteria to the new HbA(1c) criteria would have a profound impact on prevalence of diabetes among a high-risk Spanish population

AIM

To investigate changes in the prevalence of diabetes and pre-diabetes by shifting from 2-h plasma glucose and/or fasting plasma glucose diagnostic criteria to the proposed new HbA(1c) -based criteria when applied to a Mediterranean population detected to have a high risk of Type 2 diabetes.

METHODS

Individuals without diabetes aged 45-75 years (n = 2287) were screened using the Finnish Diabetes Risk Score questionnaire, a 2-h oral glucose tolerance test plus HbA(1c) test. Prevalence and degree of diagnostic overlap between three sets of criteria (2-h plasma glucose, fasting plasma glucose and HbA(1c) ) and three diagnostic categories (normal, pre-diabetes and diabetes) were calculated.

RESULTS

Defining diabetes by a single HbA(1c) measurement resulted in a dramatic decrease in prevalence (1.3%), particularly in comparison with diabetes defined by 2-h plasma glucose (8.6%), but was also significant with regard to fasting plasma glucose (2.8%). A total of 201 screened subjects (8.8%) were classified as having diabetes and 1023 (44.7%) as having pre-diabetes based on at least one of these criteria; among these, the presence of all three criteria simultaneously classified only 21 and 110 individuals respectively, about ten percent of each group. The single overlap index between subjects diagnosed as having diabetes by 2-h plasma glucose/fasting plasma glucose vs. HbA(1c) was 13.9/28%. Similarly, the single overlap index regarding pre-diabetes was 19.2/27.1%.

CONCLUSIONS

A shift from the glucose-based diagnosis to the HbA(1c) -based diagnosis for diabetes will reduce diabetes prevalence with a low overall or single degree of overlap between diagnostic categories in this high-risk Spanish population.

Stratifying and tailoring HbA1c control targets for adults with Type 2 diabetes: interpretation of the consensus proposed by the Chinese Society of Endocrinology

Glycemic control is an important goal of treatment to delay the progression of and complications associated with diabetes, but controversies exist regarding individual HbA1c control targets for different patients. With the aim of optimizing outcomes and minimizing adverse events, a preliminary consensus on HbA1c control targets for adults with Type 2 diabetes has been proposed by the Chinese Society of Endocrinology (CSE). Instead of recommending a general standard value for all patients, the CSE suggests that a relatively reasonable stratified and tailored target for individual patients should take into consideration both clinical status and social factors. Principles governing the establishment of a glycemic control target include safety, feasibility, scientific evidence, and customized care, of which the most important factor is safety. In addition to controlling plasma glucose, equal consideration should be given to other vascular disease risk factors.

Does genetic ancestry explain higher values of glycated hemoglobin in African Americans?

OBJECTIVE

Glycated hemoglobin (HbA(1c)) values are higher in African Americans than whites, raising the question of whether classification of diabetes status by HbA(1c) should differ for African Americans. We investigated the relative contribution of genetic ancestry and nongenetic factors to HbA(1c) values and the effect of genetic ancestry on diabetes classification by HbA(1c) in African Americans.

RESEARCH DESIGN AND METHODS

We performed a cross-sectional analysis of data from the community-based Atherosclerosis Risk in Communities (ARIC) Study. We estimated percentage of European genetic ancestry (PEA) for each of the 2,294 African Americans without known diabetes using 1,350 ancestry-informative markers. HbA(1c) was measured from whole-blood samples and categorized using American Diabetes Association diagnostic cut points (<5.7, 5.7-6.4, and ≥6.5%).

RESULTS

PEA was inversely correlated with HbA(1c) (adjusted r = -0.07; P < 0.001) but explained <1% of its variance. Age and socioeconomic and metabolic factors, including fasting glucose, explained 13.8% of HbA(1c) variability. Eleven percent of participants were classified as having diabetes; adjustment for fasting glucose decreased this to 4.4%. Additional adjustment for PEA did not significantly reclassify diabetes status (net reclassification index = 0.034; P = 0.94) nor did further adjustment for demographic, socioeconomic, and metabolic risk factors.

CONCLUSIONS

The relative contribution of demographic and metabolic factors far outweighs the contribution of genetic ancestry to HbA(1c) values in African Americans. Moreover, the impact of adjusting for genetic ancestry when classifying diabetes by HbA(1c) is minimal after taking into account fasting glucose levels, thus supporting the use of currently recommended HbA(1c) categories for diagnosis of diabetes in African Americans.

HbA(1c) values for defining diabetes and impaired fasting glucose in Asian Indians

AIM

To determine the glycosylated haemoglobin (HbA(1c)) cut-points for diabetes and impaired fasting glucose (IFG) among Asian Indians.

METHODS

Participants (n=525) were a random sample selected from the India Health Study. Based on history and fasting plasma glucose (FPG), participants were classified into known diabetes, newly diagnosed diabetes (NDD), impaired fasting glucose (IFG) [ADA and WHO criteria] or normal fasting glucose (NFG). Receiver Operating Characteristic curves were used to identify the optimum sensitivity and specificity for defining HbA(1c) cut-points for NDD and IFG against the FPG criteria.

RESULTS

There were 64 participants with a known history of diabetes. Of the remaining 461, IFG was present in 44.7% (ADA) and 18.2% (WHO), and 10.4% were NDD. Mean HbA(1c) were 5.4 (±0.04)% for NFG; 5.7 (±0.06)% among IFG-ADA, 5.8 (±0.09)% among IFG-WHO; 7.5 (±0.33)% for NDD and 8.4 (±0.32)% for known diabetes. Optimal HbA(1c) cut-point for NDD was 5.8% (sensitivity=75%, specificity=75.5%, AUC=0.819). Cut-point for IFG (ADA) was 5.5% (sensitivity=59.7%, specificity=59.9%, AUC=0.628) and for IFG (WHO) was 5.6% (sensitivity=60.7%, specificity=65.1%, AUC=0.671).

CONCLUSION

In this study population from north and south regions of India, the HbA(1c) cut-point that defines NDD (≥5.8%) was much lower than that proposed by an international expert committee and the American Diabetes Association (≥6.5%). A cut-point of ≥5.5% or ≥5.6% defined IFG, and was slightly lower than the ≥5.7% for high risk proposed, but accuracy was less than 70%.

A laboratory standpoint on the role of hemoglobin A1c for the diagnosis of diabetes in childhood: more doubts than certainties?

Lippi G, Targher G. A laboratory standpoint on the role of hemoglobin A1c for the diagnosis of diabetes in childhood: more doubts than certainties? The American Diabetes Association has recently included the measurement of hemoglobin A1c (A1c) among the criteria for diagnosing diabetes, so that this diagnostic strategy might also be extended in childhood and adolescence. Although the possibility of using A1c testing for screening and even diagnosing diabetes is highly appealing, A1c testing cannot be considered as yet the 'panacea' for a variety of reasons that include the suboptimal correlation with the mean blood glucose, the risk of misdiagnosis in children or adolescents with impaired renal function, iron-deficiency anemia and increased red blood cell turnover, the interference from hemoglobin variants, and the heterogeneous diagnostic performance among different populations. Additional limitations include the higher imprecision of most A1c assays (especially point-of-care testing devices) when compared with plasma glucose measurement, as well as the incremental cost deriving from routinely replacing plasma glucose with A1c determination. Taken together, the current limitations would suggest a certain degree of caution before recommending the widespread implementation of the A1c assay for diagnosing diabetes in childhood and adolescence. The potential clinical benefits (if any) of replacing blood glucose testing with A1c for diagnosing diabetes are still uncertain and will probably remain so until reliable cost-effective analyses are available.

Nontraditional markers of glycemia: associations with microvascular conditions

OBJECTIVE

To compare the associations of nontraditional (fructosamine, glycated albumin, 1,5-anhydroglucitol [1,5-AG]) and standard (fasting glucose, HbA(1c)) glycemic markers with common microvascular conditions associated with diabetes mellitus.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional study of 1,600 participants (227 with a history of diabetes and 1,323 without) from the Atherosclerosis Risk in Communities (ARIC) Study, a community-based population. We conducted logistic regression analyses of the associations of diabetes-specific tertiles of fructosamine, glycated albumin, 1/(1,5-AG), fasting glucose, and HbA(1c) with prevalence of chronic kidney disease, albuminuria, and retinopathy after adjustment for demographic, clinical, and lifestyle variables.

RESULTS

We observed significant positive trends in the associations of each marker with albuminuria and retinopathy, even after accounting for demographic, clinical, and lifestyle factors (all P trends <0.05). The associations with chronic kidney disease were similar in direction but were only significant for higher glycated albumin (P trend = 0.005), fructosamine (P trend = 0.003), and HbA(1c) (P trend = 0.005) values. After further adjustment for HbA(1c), glycated albumin and fructosamine remained significantly or borderline significantly associated with the microvascular outcomes.

CONCLUSIONS

In cross-sectional analyses, two serum markers of glycemia-glycated albumin and fructosamine-are as, or more strongly, associated with microvascular conditions as HbA(1c). These markers may be useful in settings where whole blood is not available. Whether they might complement or outperform HbA(1c) in terms of long-term predictive value requires further investigation.

Racial differences in glycemic markers: a cross-sectional analysis of community-based data

BACKGROUND

Although differences between black and white persons in hemoglobin A(1c) (HbA(1c)) values are well established, recent studies suggest that this might not reflect differences in glycemia.

OBJECTIVE

To investigate racial disparities in glycemic markers, including those that reflect biological processes independent of hemoglobin glycation and erythrocyte turnover.

DESIGN

Cross-sectional.

SETTING

Community-based.

PARTICIPANTS

1376 nondiabetic and 343 diabetic adults in a substudy of the Atherosclerosis Risk in Communities Study.

MEASUREMENTS

Hemoglobin A(1c), fasting glucose, glycated albumin, fructosamine, and 1,5-anhydroglucitol levels.

RESULTS

Among persons with and without diabetes, black persons had significantly higher HbA(1c), glycated albumin, and fructosamine levels than white persons before and after adjustment for covariates and fasting glucose concentration. Serum 1,5-anhydroglucitol levels, which are reduced in the setting of hyperglycemia-induced glycosuria, were lower in black persons than in white persons, although this difference was statistically significant only in nondiabetic adults.

LIMITATION

The design was cross-sectional, a limited number of participants with a history of diabetes was included, and the study did not include integrated measures of circulating nonfasting glycemia.

CONCLUSION

Differences between black and white persons in glycated albumin, fructosamine, and 1,5-anhydroglucitol levels parallel differences between these groups in HbA(1c) values. Racial differences in hemoglobin glycation and erythrocyte turnover cannot explain racial disparities in these serum markers. The possibility that black persons have systematically higher levels of nonfasting glycemia warrants further study.

PRIMARY FUNDING SOURCE

National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases.

Definition of prediabetes

Diabetes evolves through prediabetes, defined as impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT). Subjects with IFG/IGT have an increased risk of developing diabetes and a higher prevalence of cardiovascular disease than normoglycemic individuals. However, there is considerable evidence that glucose levels lower than those meeting the current definition of prediabetes may also be associated with similar concerns, particularly in high-risk individuals in accordance with a continuous glycemic risk perspective. Therefore, an absolute definition of prediabetes may underestimate the implications and vastness of this disorder. Research should focus on these aspects to minimize the risk of developing a preventable condition.

Implications of the new definition of diabetes for health disparities

In July 2009, an international committee announced a new diagnostic criterion for diabetes based on hemoglobin Alc (HbA1c) values. Our objective was to estimate how the new diabetes diagnostic criterion will affect the prevalence of diabetes among different race, age, and gender subpopulations, compared to the previously used fasting plasma glucose (FPG) criterion. We analyzed nationally representative data from The National Health and Nutrition Examination Survey (NHANES), aggregated from 1999 to 2006. We estimated the prevalence of known diabetes (prevalence static across either diagnostic criterion), unknown, and no diabetes (prevalence variable by criterion). We tested statistical significance of prevalence differences for unknown diabetes between the prior diagnostic criterion--FPG of at least 126 mg/dL--and the new diagnostic criterion--HbA1c of at least 6.5%--using conditional logistic regression. We further tested the association of these differences with demographic factors. The new HbA1c diagnostic criterion differentially affects different racial/ethnic groups. For non-Hispanic whites, the prevalence of undiagnosed diabetes was more than halved from 2.6% (95% confidence interval [CI], 2.2-3.1) with FPG diagnosis to 1.3% (95% CI, 1.0-1.7), P<.001 with HbAic diagnosis. For Hispanics and non-Hispanic blacks, the differences in prevalence by the 2 criteria were smaller and nonsignificant. Racial differences by diagnostic criteria were most pronounced among people aged over 55 years. Overall, the new definition of diabetes differentially affects ethnic groups, especially for older people. If the new criterion is widely adopted, over time, we may see an apparent widening of racial/ethnic disparities in diabetes prevalence.

In support of an early polypharmacy approach to the treatment of type 2 diabetes

Type 2 diabetes (T2DM) is a multifaceted disease, characterized by hyperglycaemia, resulting from a combination of insulin resistance, impaired incretin action and β-cell dysfunction leading to relative insulin deficiency. Although traditional anti-diabetes agents improve hyperglycaemia, they do so at a cost, which may entail hypoglycemia and increased body weight; exacerbating dyslipidemia, hypertension and components of insulin resistance and metabolic syndrome associated with T2DM-potentially increasing cardiovascular risk. At diagnosis, many patients with T2DM are treated with medical nutritional therapy (MNT) and exercise, then single or multiple oral anti-diabetes agents until treatment failure, when insulin is used. This strategy has been challenged by recommendations for polypharmacy approaches to the treatment of T2DM, as current strategies are unable to improve multiple aspects of the disease, nor are they likely to address underlying pathophysiology. Although the 2009 American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) treatment algorithm recommends a stepwise approach with MNT and metformin, later adding oral agents, incretin-based therapies or insulin, some experts have recommended a more aggressive approach. In his 2008 ADA Banting Lecture, Dr. Ralph DeFronzo recommended early treatment with metformin, TZD and exenatide at initiation of therapy. The authors' of this article recommend an aggressive early polypharmacy approach addressing underlying pathophysiology, including the incretin defect-with MNT and exercise, metformin and an incretin-based therapy and/or basal insulin if glycemic goal is not achieved within 3 months. This approach attempts to modify the disease, aiming for tight glycemic control, weight loss, reduced hypoglycemia, improvements to hypertension, dyslipidemia and insulin resistance-and improved cardiovascular outcomes.

Sexuality among middle-aged and older adults with diagnosed and undiagnosed diabetes: a national, population-based study

OBJECTIVE

To describe sexual activity, behavior, and problems among middle-age and older adults by diabetes status.

RESEARCH DESIGN AND METHODS

This was a substudy of 1,993 community-residing adults, aged 57-85 years, from a cross-sectional, nationally representative sample (N = 3,005). In-home interviews, observed medications, and A1C were used to stratify by diagnosed diabetes, undiagnosed diabetes, or no diabetes. Logistic regression was used to model associations between diabetes conditions and sexual characteristics, separately by gender.

RESULTS

The survey response rate was 75.5%. More than 60% of partnered individuals with diagnosed diabetes were sexually active. Women with diagnosed diabetes were less likely than men with diagnosed diabetes (adjusted odds ratio 0.28 [95% CI 0.16-0.49]) and other women (0.63 [0.45-0.87]) to be sexually active. Partnered sexual behaviors did not differ by gender or diabetes status. The prevalence of orgasm problems was similarly elevated among men with diagnosed and undiagnosed diabetes compared with that for other men, but erectile difficulties were elevated only among men with diagnosed diabetes (2.51 [1.53 to 4.14]). Women with undiagnosed diabetes were less likely to have discussed sex with a physician (11%) than women with diagnosed diabetes (19%) and men with undiagnosed (28%) or diagnosed (47%) diabetes.

CONCLUSIONS

Many middle-age and older adults with diabetes are sexually active and engage in sexual behaviors similarly to individuals without diabetes. Women with diabetes were more likely than men to cease all sexual activity. Older women with diabetes are as likely to have sexual problems but are significantly less likely than men to discuss them.

Screening for diabetes and pre-diabetes with proposed A1C-based diagnostic criteria

OBJECTIVE

An International Expert Committee (IEC) and the American Diabetes Association (ADA) proposed diagnostic criteria for diabetes and pre-diabetes based on A1C levels. We hypothesized that screening for diabetes and pre-diabetes with A1C measurements would differ from using oral glucose tolerance tests (OGTT).

RESEARCH DESIGN AND METHODS

We compared pre-diabetes, dysglycemia (diabetes or pre-diabetes), and diabetes identified by the proposed criteria (A1C ≥ 6.5% for diabetes and 6.0-6.4% [IEC] or 5.7-6.4% [ADA] for high risk/pre-diabetes) with standard OGTT diagnoses in three datasets. Non-Hispanic white or black adults without known diabetes who had A1C and 75-g OGTT measurements were included from the prospective Screening for Impaired Glucose Tolerance study (n = 1,581), and from the National Health and Nutrition Examination Survey (NHANES) III (n = 2014), and NHANES 2005-2006 (n = 1,111).

RESULTS

OGTTs revealed pre-diabetes in 35.8% and diabetes in 5.2% of combined study subjects. A1C provided receiver operating characteristic (ROC) curve areas for diabetes of 0.79-0.83, but ROC curve areas were ≤ 0.70 for dysglycemia or pre-diabetes. The proposed criteria missed 70% of individuals with diabetes, 71-84% with dysglycemia, and 82-94% with pre-diabetes. Compared with the IEC criteria, the ADA criteria for pre-diabetes resulted in fewer false-negative and more false-positive result. There were also racial differences, with false-positive results being more common in black subjects and false-negative results being more common in white subjects. With use of NHANES 2005-2006 data, ∼5.9 million non-Hispanic U.S. adults with unrecognized diabetes and 43-52 million with pre-diabetes would be missed by screening with A1C. CONCLUSIONS The proposed A1C diagnostic criteria are insensitive and racially discrepant for screening, missing most Americans with undiagnosed diabetes and pre-diabetes.

A1C to detect diabetes in healthy adults: when should we recheck?

OBJECTIVE

To evaluate the optimal interval for rechecking A1C levels below the diagnostic threshold of 6.5% for healthy adults.

RESEARCH DESIGN AND METHODS

This was a retrospective cohort study. Participants were 16,313 apparently healthy Japanese adults not taking glucose-lowering medications at baseline. Annual A1C measures from 2005 to 2008 at the Center for Preventive Medicine, a community teaching hospital in Japan, estimated cumulative incidence of diabetes.

RESULTS

Mean age (+/-SD) of participants was 49.7 +/- 12.3 years, and 53% were male. Mean A1C at baseline was 5.4 +/- 0.5%. At 3 years, for those with A1C at baseline of <5.0%, 5.0-5.4%, 5.5-5.9%, and 6.0-6.4%, cumulative incidence (95% CI) was 0.05% (0.001-0.3), 0.05% (0.01-0.11), 1.2% (0.9-1.6), and 20% (18-23), respectively.

CONCLUSIONS

In those with an A1C <6.0%, rescreening at intervals shorter than 3 years identifies few individuals (approximately <or=1%) with an A1C >or=6.5%.

Glycated hemoglobin (HbA1c): old dogmas, a new perspective?

The hemoglobin A1c (HbA1c) assay provides a reliable measure of chronic glycemia and correlates well with the risk of long-term diabetes complications, so that it is currently considered the test of choice for monitoring and chronic management of diabetes. Recently, HbA1c testing has been included within the diagnostic criteria recommended for diagnosis of diabetes in nonpregnant individuals by the American Diabetes Association (ADA). The emerging concept that HbA1c can be used rather than blood glucose in the diagnosis of diabetes is highly appealing for a variety of reasons, including less sensitivity to preanalytical variables, lower within subject biological variability, little to null interference from diurnal variations, acute stress and common drugs which are known to influence glucose metabolism, as well as the fact that one single measurement might provide information for both diagnosing diabetes and tracking glycemic control. On the other hand, the use of HbA1c for screening and diagnosing diabetes also carries some limitations, including the worse diagnostic performance in different populations (i.e., pregnancy, elderly and non-Hispanic blacks), the risk of overdiagnosis in subjects with iron deficiency anemia, in subjects genetically predisposed to hyperglycation, and in those with increased red blood cell turnover. There is also a higher risk of misdiagnosis in patients with end-stage renal disease and heavy alcohol consumption. Finally, HbA1c testing might be biased due to the interference from several hemoglobin variants, is characterized by a higher imprecision than blood glucose measurement, and is more expensive. This paper will critically summarize the potential advantages and limitations of HbA1c as a recommended test for diagnosing diabetes.