The proposed terminology 'A(1c)-derived average glucose' is inherently imprecise and should not be adopted

Association between the stress-hyperglycemia ratio and all-cause mortality in community-dwelling populations: An analysis of the National Health and Nutrition Examination Survey (NHANES) 1999-2014

BACKGROUND

Reportedly, the stress-hyperglycemia ratio (SHR) is closely associated with poor prognosis in patients with severe acute disease. However, the community-dwelling may also be in a state of stress due to environmental exposure. Our study aimed to explore the association between SHR and all-cause mortality in the community-dwelling population.

METHODS

A total of 18 480 participants were included out of 82 091 from the NHANES 1999-2014 survey. The Kaplan-Meier survival analyses were used to assess the disparities in survival rates based on SHR, and the log-rank test was employed to investigate the distinctions between groups. The multivariate Cox regression analysis and restricted cubic spline (RCS) analysis were performed to assess the association of SHR with all-cause mortality. A subgroup analysis was also conducted.

RESULTS

A total of 3188 deaths occurred during a median follow-up period of 11.0 (7.7; 15.4) years. The highest risk for all-cause mortality was observed when SHR≤ 0.843 or SHR ≥0.986 (log-rank p < .001). After adjusting for the confounding factors, compared with subjects in the second SHR quartile (Q2), participants in the highest (Q4, adjusted hazard ratio [HR] 1.49, 95% confidence interval [CI] 1.28-1.73) and lowest quartiles (Q1, adjusted HR 1.37, 95% CI 1.16-1.60) have a higher probability of all-cause death. The RCS observed a dose-response U-shaped association between SHR and all-cause mortality. The U-shaped association between SHR and all-cause mortality was similar across subgroup analysis.

CONCLUSIONS

The SHR was significantly associated with all-cause mortality in the community-dwelling population, and the relationship was U-shaped.

Clinical validation of electrochemical biosensor for the detection of methylglyoxal in subjects with type-2 diabetes mellitus

Methylglyoxal (MG), a highly reactive by-product of glycolysis, is involved in the formation of advanced glycation end-products (AGEs). Elevated levels of MG have been correlated with micro-and macro-angiopathic complications in diabetes, including neuropathy, kidney disease, retinopathy, and cardiovascular disease. Therefore, point-of-care devices for detecting MG may be of great use in the screening of diabetes complications. This study was designed to determine the utility of the developed electrochemical biosensor to measure the level of MG in human plasma from type-2 diabetes mellitus patients. Electrochemical studies were carried out with optimized experimental parameters using the modified Platinum-electrode. Subsequently, clinical studies using 350 blood plasma samples were conducted and the results were validated against the ELISA kit, Normal Glucose Tolerance (NGT), and glycosylated haemoglobin (HbA1c). The MG sensor exhibited a linear range of 1.0-7.5 μM concentration with a sensitivity of 1.02 mA µM-1, a limit of detection of 0.21 µM, a limit of quantification of 0.70 µM and a response time less than 10 s. The sensor showed 90% correlation with ELISA data. The developed biosensor showed a significant correlation with HbA1c and fasting plasma glucose suggesting that it can be used as a point-of-care device to screen for diabetes.

Differences between HbA1c and glucose-related variables in predicting weight loss and glycaemic changes in individuals with overweight and hyperglycaemia - The PREVIEW trial

AIMS

To examine the differences between HbA_1c and glucose related variables in predicting weight loss and glycaemic changes following 8 weeks of low energy diet (LED) in individuals with overweight and hyperglycaemia.

RESEARCH DESIGN AND METHODS

2178 individuals with ADA-defined pre-diabetes - impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) - who started an 8 week LED weight loss diet, were included in this analysis. Participants were enrolled in the PREVIEW (PREVention of diabetes through lifestyle interventions and population studies In Europe and around the World) clinical trial. Multivariable linear mixed effects regression models and generalised additive mixed effect logistic models were used.

RESULTS

Only 1 in 3 participants (33%) had HbA_1c levels defined as pre-diabetes. Neither baseline HbA_1c, IFG or IGT were associated with body weight change at 8 weeks. Higher baseline body weight, baseline fasting insulin and weight loss predicted normalisation of fasting plasma glucose (FPG), whilst higher baseline fasting insulin, C-reactive protein (hsCRP) and older age predicted normalisation of HbA_1c. Additionally, male sex and higher baseline BMI, body fat and energy intake were positively associated with weight loss, whereas greater age and higher HDL-cholesterol predicted less weight loss.

CONCLUSIONS

Whilst neither HbA_1c nor fasting glucose predicts short-term weight loss success, both may impact the metabolic response to rapid weight loss. We propose a role of inflammation versus total body adiposity since these variables are independent predictors of the normalisation of HbA_1c and fasting glucose, respectively.

Serum IRAP, a Novel Direct Biomarker of Prediabetes and Type 2 Diabetes?

Insulin resistance (IR), currently called prediabetes (PD), affects more than half of the adult population worldwide. Type 2 diabetes (T2D), which often follows in the absence of treatment, affects more than 475 million people and represents 10–20% of the health budget in industrialized countries. A preventive public health policy is urgently needed in order to stop this constantly progressing epidemic. Indeed, early management of prediabetes does not only strongly reduce its evolution toward T2D but also strongly reduces the appearance of cardiovascular comorbidity as well as that of associated cancers. There is however currently no simple and reliable test available for the diagnosis or screening of prediabetes and it is generally estimated that 20–60% of diabetics are not diagnosed. We therefore developed an ELISA for the quantitative determination of serum Insulin-Regulated AminoPeptidase (IRAP). IRAP is associated with and translocated in a stoechiometric fashion to the plasma membrane together with GLUT4 in response to insulin in skeletal muscle and adipose tissue which are the two major glucose storage sites. Its extracellular domain (IRAPs) is subsequently cleaved and secreted in the blood stream. In T2D, IRAP translocation in response to insulin is strongly decreased. Our patented sandwich ELISA is highly sensitive (≥10.000-fold “normal” fasting concentrations) and specific, robust and very cost-effective. Dispersion of fasting plasma concentration values in a healthy population is very low (101.4 ± 15.9 μg/ml) as compared to those of insulin (21–181 pmol/l) and C-peptide (0.4–1.7 nmol/l). Results of pilot studies indicate a clear correlation between IRAPs levels and insulin sensitivity. We therefore think that plasma IRAPs may be a direct marker of insulin sensitivity and that the quantitative determination of its plasma levels should allow large-scale screening of populations at risk for PD and T2D, thereby allow the enforcement of a preventive health policy aiming at efficiently reducing this epidemic.

Results of a Study Comparing Glycated Albumin to Other Glycemic Indices

CONTEXT

Intermediate-term glycemic control metrics fulfill a need for measures beyond hemoglobin A1C.

OBJECTIVE

Compare glycated albumin (GA), a 14-day blood glucose measure, with other glycemic indices.

DESIGN

24-week prospective study of assay performance.

SETTING

8 US clinics.

PARTICIPANTS

Subjects with type 1 (n = 73) and type 2 diabetes (n = 77) undergoing changes to improve glycemic control (n = 98) or with stable diabetes therapy (n = 52).

INTERVENTIONS

GA, fructosamine, and A1C measured at prespecified intervals. Mean blood glucose (MBG) calculated using weekly self-monitored blood glucose profiles.

MAIN OUTCOME MEASURES

Primary: Pearson correlation between GA and fructosamine. Secondary: magnitude (Spearman correlation) and direction (Kendall correlation) of change of glycemic indices in the first 3 months after a change in diabetes management.

RESULTS

GA was more concordant (60.8%) with changes in MBG than fructosamine (55.5%) or A1C (45.5%). Across all subjects and visits, the GA Pearson correlation with fructosamine was 0.920. Pearson correlations with A1C were 0.655 for GA and 0.515 for fructosamine (P < .001) and with MBG were 0.590 and 0.454, respectively (P < .001). At the individual subject level, Pearson correlations with both A1C and MBG were higher for GA than for fructosamine in 56% of subjects; only 4% of subjects had higher fructosamine correlations with A1C and MBG. GA had a higher Pearson correlation with A1C and MBG in 82% and 70% of subjects, respectively.

CONCLUSIONS

Compared with fructosamine, GA correlates significantly better with both short-term MBG and long-term A1C and may be more useful than fructosamine in clinical situations requiring monitoring of intermediate-term glycemic control (NCT02489773).

Effect of Dapagliflozin on Glycemic Variability in Patients with Type 2 Diabetes under Insulin Glargine Combined with Other Oral Hypoglycemic Drugs

AIM

To evaluate the effect of an inhibitor of sodium-glucose cotransporter 2 (SGLT-2 inhibitor, dapagliflozin) on glycemic variability in type 2 diabetes mellitus (T2D) under insulin glargine combined with oral hypoglycemic drugs, using a continuous glucose monitoring system (CGMS).

METHODS

This prospective, self-controlled, single-center clinical trial recruited 36 patients with T2D under combined insulin glargine and oral hypoglycemic drugs. General clinical data were collected. Fasting blood glucose (FBG), postprandial blood glucose (PBG), glycosylated hemoglobin (HbA1c), and C-peptide levels were assessed before and four weeks of dapagliflozin (10 mg per day) treatment. Blood glucose was monitored for 72 hours before and after treatment using CGMS.

RESULTS

After treatment with dapagliflozin, FBG decreased from 6.74 ± 1.78 to 5.95 ± 1.13 mmol/L (p < 0.05); PBG decreased from 13.04 ± 2.99 to 10.92 ± 3.26 mmol/L (p < 0.05); HbA1c decreased from 7.37 ± 0.96% to 6.94 ± 0.80%. The proportion of patients with HbA1c < 7% increased from 27.8% to 58.3%, and the proportion of patients with HbA1c < 7% and without level 2 hypoglycemia increased from 27.8% to 55.6% (p < 0.05). CGMS data showed reduction of the 24 h MBG, MAGE, time-above-range (TAR, >10 mmol/L), high blood glucose index (HBGI), glucose management indicator (GMI), and incremental area under the curve of the glucose level more than 10 mmol/L (AUC > 10) and an increase of time-in-range (TIR, 3.9-10 mmol/L) with treatment. Homeostasis model assessment for pancreatic beta-cell function (HOMA-beta) increased significantly with treatment (p < 0.05), and fewer insulin doses were required after the treatment, without increasing in hypoglycemia and urinary tract infection. Further, a stratified analysis showed that patients with higher pretreatment HbA1c and waist-to-hip ratio (WHR) had greater improvement in glycemic control.

CONCLUSION

Dapagliflozin may reduce blood glucose levels, ameliorate glycemic variability, and improve pancreatic beta-cell function in patients with T2D under insulin glargine combined with other oral hypoglycemic drugs, especially in those with poor glucose control and abdominal obesity.

Beyond HbA1c

It can scarcely be denied that the supreme goal of all theory is to make the irreducible basic elements as simple and as few as possible without having to surrender the adequate representation of a single datum of experience. The diaTribe Foundation convened a meeting on the topic of glycemic outcomes beyond HbA1c on 21 July 2017, in Bethesda (MD, USA), focusing on potential uses of continuous glucose monitoring (CGM). Understanding patterns of glycemia in people with diabetes has long been a focus of approaches to improving treatment, and over the past few years this has become an available modality for clinical practice. Glucose levels are not the only biologic parameters affecting HbA1c levels; HbA1c changes with anemia or, more subtly, with changes in rates of erythrocyte turnover not reflected in hemoglobin levels outside the normal range. Renal disease often is associated with lower HbA1c than would be predicted based on an individual's glycemic levels. Furthermore, HbA1c levels tend to increase with age and are higher in some ethnic groups; for example, people of African ethnicity have higher HbA1c levels than people of Northern European descent. Indeed, we have argued that even as a measure of mean glycemia HbA1c is inherently imprecise. Overall, for some 20% of people with diabetes, HbA1c levels are substantially higher, or substantially lower, than those that would be predicted from mean blood glucose levels. If one recognizes that HbA1c is, at best, a partial measure of mean glycemic exposure, one must surely accept that HbA1c does not reflect variability within a day, from day to day, and from period to period. Many glucose-lowering medicines, particularly the sulfonylureas and insulin, cause hypoglycemia, with consequent negative effects on quality of life and patient-reported outcomes, as well as association with weight gain and adverse macrovascular outcome; hypoglycemia will, of course, not be captured by HbA1c measurement. Based on these considerations, HbA1c may be more limited than generally recognized as a surrogate marker of optimal diabetes treatment, leading the European Medicines Agency to consider relying less on this measure, with the implication that novel approaches will be required for clinical practice and for clinical trials in developing future medicines. In surveys performed by a market research company (dQ&A Market Research, San Francisco, CA, USA) and reported at the Bethesda meeting, among >3000 people with type 1 (T1D) or type 2 (T2D) diabetes both receiving and not receiving insulin, the majority reported a sense that their diabetes care is not very successful and that too much of their time was spent outside the 70-180 mg/dL (3.9-10.0 mEq/L) range. Although self-monitoring of capillary blood glucose (SMBG) is an important tool for patients to use in understanding glycemic excursions, CGM offers a far superior technology in this regard and can avoid the erroneous conclusions often accompanying the use of the inherently indirect measurement of HbA1c. Duration and severity of hypoglycemia may come to be considered important medication efficacy measures, rather than just being considered safety outcomes. Glucose cut-off levels suggested at the meeting may be: <54 mg/dL (3.0 mEq/L) for severe hypoglycemia, <70 mg/dL (3.9 mEq/L) for low blood glucose levels, >180 mg/dL (10.0 mEq/L) for high blood glucose levels, and >240 mg/dL (13.3 mEq/L) for serious high blood glucose levels. An important part of both SMBG and CGM technologies will be the development of data transmission and storage modalities to better provide feedback to people with diabetes and health care providers in adjusting a variety of treatments, as well as their growing use in insulin dose adjustment algorithms; important in such approaches will be the integration of SMBG with CGM to recognize potential measurement errors and to improve the accuracy and assurance of patients and providers that the CGM results are accurate, a particular concern for readings in the hypoglycemia range, but remaining an issue throughout the clinical glycemia range. However, one must recognize that many commercially available SMBG instruments also fail to exhibit required accuracy, and that the indirect relationship between HbA1c and blood glucose suggests that HbA1c is at best limited in its portrayal of glycemic exposure. All these modalities play a role, but the use of CGM appears crucial to the development of better approaches to clinical treatment with multiple views allowing understanding of patterns of glycemic exposure. We look forward to further improvements in this methodology.

GLYCATED ALBUMIN AT 4 WEEKS CORRELATES WITH A1C LEVELS AT 12 WEEKS AND REFLECTS SHORT-TERM GLUCOSE FLUCTUATIONS

OBJECTIVE

Evaluate the performance of glycated albumin (GA) monitoring by comparing it to other measures of glycemic control during intensification of antidiabetic therapy.

METHODS

This 12-week, prospective, multicenter study compared the diagnostic clinical performance of GA to glycated hemoglobin A1C (A1C), fructosamine corrected for albumin (FRA), fasting plasma glucose (FPG), and mean blood glucose (MBG) estimated from self-monitoring of blood glucose (SMBG) and continuous glucose monitoring (CGM) in 30 patients with suboptimally controlled type 1 or 2 diabetes.

RESULTS

Mean A1C decreased from 9.5% to 8.1%. Mean SMBG correlated closely with CGM (Pearson r = 0.783 for daily estimates and r = 0.746 for weekly estimates, P<.0001). Both GA and FRA levels significantly correlated with changes from baseline in A1C and mean weekly SMBG (P<.001). The lowest observed median GA occurred at 4 weeks, followed by a small increase and then a slight reduction, mirroring changes in overall mean SMBG values. The median A1C fell throughout the treatment period, failing to reflect short-term changes in SMBG. A ≥1% reduction in GA at 4 weeks was significantly associated with a ≥0.5% change in A1C at 12 weeks (odds ratio [OR] = 19.0, 95% confidence interval [CI]: 1.4, 944, P = .018).

CONCLUSION

In patients receiving glucose-lowering therapy, changes in GA at 4 weeks were concordant with changes in A1C at 12 weeks, and both GA and FRA more accurately reflected short-term blood glucose fluctuations than A1C.

Prediabetes diagnosis and treatment: A review

Prediabetes is an intermediate state of hyperglycemia with glycemic parameters above normal but below the diabetes threshold. While, the diagnostic criteria of prediabetes are not uniform across various international professional organizations, it remains a state of high risk for developing diabetes with yearly conversion rate of 5%-10%. Observational evidence suggests as association between prediabetes and complications of diabetes such early nephropathy, small fiber neuropathy, early retinopathy and risk of macrovascular disease. Several studies have shown efficacy of lifestyle interventions with regards to diabetes prevention with a relative risk reduction of 40%-70% in adults with prediabetes. While there is increasing evidence to prove the efficacy of pharmacotherapy in prevention of diabetes in adults with prediabetes, pharmaceutical treatment options other than metformin are associated with adverse effects that limit their use for prediabetes. There are no reports of systematic evaluation of health outcomes related to prediabetes in children. The effects of pharmacotherapy of prediabetes on growth and pubertal development in children remains unknown. Secondary intervention with pharmacotherapy with metformin is advocated for high-risk individuals but criteria for such consideration benefit of early intervention, long term cost effectiveness of such interventions and the end point of therapy remain unclear. Pharmacotherapy must be used with caution in children with prediabetes. Prediabetes is a condition defined as having blood glucose levels above normal but below the defined threshold of diabetes. It is considered to be an at risk state, with high chances of developing diabetes. While, prediabetes is commonly an asymptomatic condition, there is always presence of prediabetes before the onset of diabetes. The elevation of blood sugar is a continuum and hence prediabetes can not be considered an entirely benign condition. This aim of this review is to describe the challenges associated with diagnosis of prediabetes, the possible adverse medical outcomes associated with prediabetes and the treatment options and rationale for their use in context of prediabetes.

The diagnostic threshold of HbA1c and impact of its use on diabetes prevalence-a population-based survey of 6898 Han participants from southern China

OBJECTIVE

The objective of this study is to determine the diagnostic threshold of HbA1c for diabetes and the impact of using it on diabetes prevalence.

METHODS

A population-based stratified study was conducted in 2010 among community-dwelling adults aged ≥35years in southern China. Participants without previously-diagnosed diabetes (PDD) took oral glucose tolerance test (OGTT) and HbA1c assay. HbA1c diagnostic threshold was determined by receiver operating characteristic curve.

RESULTS

A total of 6989 participants with mean age of 52years were recruited. The area under curve of HbA1c was 0.903 (95% CI: 0.883-0.922), with optimal cut-off value at 6.25% (sensitivity 75.6% and specificity 91.9%). There were 449 (6.42%) patients with PDD and 422 (6.04%), 815 (11.66%) and 918 (13.13%) new cases diagnosed by OGTT, HbA1c ≥6.25% or either, respectively. When either HbA1c or OGTT was used, newly-diagnosed diabetes prevalence increased by 117.4%.

CONCLUSIONS

Diabetes is prevalent in southern China. Near half of the patients go undetected with current diagnostic criteria. HbA1c ≥6.25% may be the diagnostic threshold value but needs further verification. The introduction of HbA1c threshold into diabetes diagnosis in China will cause a substantial increase in diabetes prevalence and great challenge on the public healthcare system.

Ethnic differences in glycemic markers in patients with type 2 diabetes

OBJECTIVE

Recent studies have reported hemoglobin A1c (HbA1c) differences across ethnic groups that could limit its use in clinical practice. The authors of the A1C-Derived Average Glucose study have advocated to report HbA1c in estimated average glucose (AG) equivalents. The aim of this study was to assess the relationships between HbA1c and the mean of three 7-point self-monitored blood glucose (BG) profiles, and to assess whether estimated AG is an accurate measure of glycemia in different ethnic groups.

RESEARCH DESIGN AND METHODS

We evaluated 1,879 participants with type 2 diabetes in the DURABLE trial who were 30 to 80 years of age, from 11 countries, and, according to self-reported ethnic origin, were Caucasian, of African descent (black), Asian, or Hispanic. We performed logistic regression of the relationship between the mean self-monitored BG and HbA1c, and estimated AG, according to ethnic background.

RESULTS

Baseline mean (SD) HbA1c was 9.0% (1.3) (75 [SD, 14] mmol/mol), and mean self-monitored BG was 12.1 mmol/L (3.1) (217 [SD, 55] mg/dL). In the clinically relevant HbA1c range of 7.0-9.0% (53-75 mmol/mol), non-Caucasian ethnic groups had 0.2-0.5% (2-6 mmol/mol) higher HbA1c compared with Caucasians for a given BG level. At the mean self-monitored BG levels≤11.6 mmol/L, estimated AG overestimated the actual average BG; at levels>11.6 mmol/L, estimated AG underestimated the actual BG levels.

CONCLUSIONS

For a given degree of glycemia, HbA1c levels vary among different ethnic groups. Ethnicity needs to be taken into account when using HbA1c to assess glycemic control or to set glycemic targets. Estimated AG is not a reliable marker for mean glycemia and therefore is of limited clinical value.

Hemoglobin A1c can identify more cardiovascular and metabolic risk profile in OGTT-negative Chinese population

OBJECTIVE

To investigate the significance of hemoglobin A1c (HbA1c) in cardiovascular and metabolic risk stratification among diabetes and non-diabetes in southern Chinese.

METHODS

Indigenous adults (aged more than or equal to 35 years) without known diabetes were enrolled in the cross-sectional survey. According to oral glucose tolerance test (OGTT), participants were categorized into OGTT-negative group and OGTT-positive group. Cardiovascular and metabolic risk profile was compared between different HbA1c levels (≥ 6.5% vs. < 6.5%) in each group.

RESULTS

The prevalence of OGTT-diagnosed diabetes was 6.45% (422/6540). In OGTT-negative group, subjects with HbA1c ≥ 6.5% were older, had higher prevalence of coronary heart disease, current smoking, hypertension, obesity and abdominal obesity. They also had higher body weight, waist-hip ratio, body mass index, glucose levels (fasting plasma glucose, 2-hour plasma glucose and HbA1c), and lipid levels (total cholesterol and low density lipoprotein cholesterol). In OGTT-positive group, patients with HbA1c ≥ 6.5% identified less cardiovascular and metabolic risk file than that in OGTT-negative group.

CONCLUSIONS

Subjects with HbA1c ≥ 6.5% have more unfavorable cardiovascular and metabolic risk profile than those with HbA1c < 6.5%, especially in OGTT-negative population. More attention should be paid to this subgroup in clinical practice.

Update on diabetes diagnosis: a historical review of the dilemma of the diagnostic utility of glycohemoglobin A1c and a proposal for a combined glucose-A1c diagnostic method

The role of glycohemoglobin A1c (A1c) for the diagnosis of diabetes has been debated for over three decades. Recently, the American Diabetes Association (ADA) has recommended adding A1c as an additional criterion for diabetes diagnosis. In view of the continued debate about the diagnostic utility of A1c, and in view of the unabated burden of undiagnosed diabetes, the search for alternative diagnostic methods is discussed. A historical literature review is provided, in view of the new ADA diagnostic guidelines, and a proposal is provided for combining A1c and a glucose measurement as a diagnostic alternative/adjunct to the use of a single criterion. This proposal is based on the non-overlapping of the advantages and disadvantages of these individual tests. The cost-effectiveness of this method remains to be tested.

Identifying dysglycemic states in older adults: implications of the emerging use of hemoglobin A1c

CONTEXT

Hemoglobin A1c (A1c) was recently added to the diagnostic criteria for diabetes and prediabetes.

OBJECTIVE

Our objective was to examine performance of A1c in comparison with fasting plasma glucose (FPG) in diagnosing dysglycemia in older adults.

DESIGN AND SETTING

We conducted a cross-sectional analysis of data from the Health, Aging, and Body Composition study at yr 4 (2000-2001) when FPG and standardized A1c measurements were available.

PARTICIPANTS

Of 3075 persons (aged 70-79 yr, 48% men, 42% Black) at study entry, 1865 participants without known diabetes who had appropriate measures were included.

MAIN OUTCOME MEASURES

Sensitivity and specificity of A1c-based diagnoses were compared with those based on FPG and the proportion of participants identified with dysglycemia by each measure.

RESULTS

Of all participants, 2.7 and 3.1% had undiagnosed diabetes by FPG≥126 mg/dl and A1c≥6.5%, respectively. Among the remaining participants, 21.1% had prediabetes by impaired fasting glucose (≥100 mg/dl) and 22.2% by A1c≥5.7%. Roughly one third of individuals with diabetes and prediabetes were identified by either FPG or A1c alone and by both tests simultaneously. Sensitivities and specificities of A1c compared with FPG were 56.9 and 98.4% for diabetes and 47.0 and 84.5% for prediabetes, respectively. Blacks and women were more likely to be identified with dysglycemia by A1c than FPG.

CONCLUSIONS

In this older population, we found considerable discordance between FPG- and A1c-based diagnosis of diabetes and prediabetes, with differences accentuated by race and gender. Broad implementation of A1c to diagnose dysglycemic states may substantially alter the epidemiology of these conditions in older Americans.

Glycated haemoglobin in diabetic women with and without HIV infection: data from the Women's Interagency HIV Study

BACKGROUND

Limited data suggest that glycated haemoglobin (haemoglobin A1c; A1C) values might not reflect glycaemic control accurately in HIV-infected individuals with diabetes.

METHODS

We evaluated repeated measures of paired fasting glucose and A1C values in 315 HIV-infected and 109 HIV-uninfected diabetic participants in the Women's Interagency HIV Study. Generalized estimating equations used log A1C as the outcome variable, with adjustment for log fasting glucose concentration in all models.

RESULTS

An HIV-infected woman on average had 0.9868 times as much A1C (that is, 1.32% lower; 95% confidence interval 0.9734-0.9904) as an HIV-uninfected woman with the same log fasting glucose concentration. In multivariate analyses, HIV serostatus was not associated, but White, other non-Black race, and higher red blood cell mean corpuscular volume (MCV) were statistically associated with lower A1C values. Use of diabetic medication was associated with higher A1C values. In multivariate analyses restricted to HIV-infected women, White and other race, higher MCV, and HCV viraemia were associated with lower A1C values, whereas older age, use of diabetic medications and higher CD4(+) T-cell count were associated with higher A1C values. Use of combination antiretroviral therapy, protease inhibitors, zidovudine, stavudine or abacavir was not associated with A1C values.

CONCLUSIONS

A1C values were modestly lower in HIV-infected diabetic women relative to HIV-uninfected diabetic women after adjustment for fasting glucose concentration. The difference was abrogated by adjustment for MCV, race and diabetic medication use. Our data suggest that in clinical practice A1C gives a reasonably accurate refection of glycaemic control in HIV-infected diabetic women.

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.

Estimated average glucose and self-monitored mean blood glucose are discordant estimates of glycemic control

OBJECTIVE

The A1C-Derived Average Glucose study recommended reporting A1C in estimated average glucose (eAG) equivalents. We compared eAG with self-monitored mean blood glucose (MBG) to determine whether eAG is systematically biased due to biological variation in the relationship between MBG and A1C.

RESEARCH DESIGN AND METHODS

MBG and A1C were recorded from charts of 202 pediatric type 1 diabetic patients at 1,612 clinic visits. Patients were divided into groups with low, moderate, or high A1C bias based on a hemoglobin glycation index (HGI).

RESULTS

The mean +/- SD values for MBG versus eAG were as follows: total population, 194 +/- 34 vs. 196 +/- 36 mg/dl; low-HGI group, 186 +/- 31 vs. 163 +/- 20 mg/dl; moderate-HGI group, 195 +/- 28 vs. 193 +/- 19 mg/dl; and high-HGI group, 199 +/- 42 vs. 230 +/- 31 mg/dl.

CONCLUSIONS

eAG underestimated MBG in low HGI patients and overestimated MBG in high HGI patients. Disagreement between eAG and MBG downloaded from patient glucose meters will cause confusion if eAG is implemented for clinical use.

Does A1c consistently reflect mean plasma glucose?

BACKGROUND

A1c, a surrogate measure of glycemic control, is known to have a strong linear correlation with mean plasma glucose (MPG) when analyzed in populations of patients. However, clinically significant intersubject variability in this relationship exists, which suggests that A1c measurements may not reflect actual glycemic control in some patients. In the present study we explored the extent to which A1c accurately represents glycemic control, as measured by MPG, for individual patients.

METHODS

Data were pooled from randomized clinical trials in which A1c and self-monitored plasma glucose (SMPG) profiles were collected by patients with Type 2 diabetes treated with insulin analog regimens. MPG levels were calculated from SMPG profiles. Distributions of MPG were analyzed for patients within similar ranges of A1c (<6.5%, 6.5%-<7.5%, 7.5%-<8.5%, 8.5%-<9.5%, and ≥9.5%) and distributions of A1c were analyzed in patients within similar ranges of MPG (<6.1, 6.1-<7.8, 7.8-<9.4, 9.4-<11.1, and ≥11.1 mmol/L).

RESULTS

Substantial proportions of patients had clinically significant differences between A1c and MPG. For example, among 260 patients with A1c between 6.5% and 7.5%, 10% had MPG levels <6.4 mmol/L, whereas 10% had MPG >9.5 mmol/L. Among the 224 patients with MPG levels ≥6.1 mmol/L and <7.8 mmol/L, 10% had A1c <6% and 10% had A1c >8.1%.

CONCLUSIONS

In the absence of SMPG, A1c may inadequately represent glycemic control for many diabetic patients.

Can 'personalized diagnostics' promote earlier intervention for dysglycaemia? Hypothesis ready for testing

The risk associated with progression to diabetes as well as for cardiovascular complications increases along a continuum, rather than being threshold-dependent. How can we identify those with glucose levels in the upper reaches of normal who are most in need of a preventive intervention? With present criteria, we are likely excluding many individuals who have heightened risk. We introduce here the possibility of using a "personalized" glucose profile to encourage early intervention in subjects in whom glucose metabolism is deteriorating (on an individual level) but not yet abnormal on a population-based norm. We further suggest that "personalized profiles" of hemoglobin A1c and basal plasma insulin may also help encourage appropriately early intervention. That the first line therapies are so effective, safe and simple make these more sensitive approaches very attractive.

HbA1c: how do we measure it and what does it mean?

PURPOSE OF REVIEW

Description of recent developments in the standardization of HbA1c measurement and interpretation of HbA1c results.

RECENT FINDINGS

HbA1c is extensively used in the management of patients with diabetes. The two major schemes to standardize HbA1c produce values that differ substantially. A prospective, multinational study revealed a linear correlation between HbA1c and average blood glucose. Some, but not all, assay methods are able to accurately measure HbA1c in individuals with common hemoglobin variants.

SUMMARY

Progress in standardization of methods for HbA1c measurement has significantly reduced variation among different methods. The improved accuracy could allow HbA1c to be used for screening and diagnosis of diabetes. A consensus document recommends that HbA1c be reported in both NGSP (%) and IFCC (mmol/mol) units. HbA1c results can be translated into estimated average glucose (eAG), which could be reported in addition to HbA1c.

Review of hemoglobin A(1c) in the management of diabetes

Hemoglobin HbA(1c) (A(1c)) has been used clinically since the 1980s as a test of glycemic control in individuals with diabetes. The Diabetes Control and Complications Trial (DCCT) demonstrated that tight glycemic control, quantified by lower blood glucose and A(1c) levels, reduced the risk of the development of complications from diabetes. Subsequently, standardization of A(1c) measurement was introduced in different countries to ensure accuracy in A(1c) results. Recently, the International Federation of Clinical Chemists (IFCC) introduced a more precise measurement of A(1c) , which has gained international acceptance. However, if the IFCC A(1c) result is expressed as a percentage, it is lower than the current DCCT-aligned A(1c) result, which may lead to confusion and deterioration in diabetic control. Alternative methods of reporting have been proposed, including A(1c) -derived average glucose (ADAG), which derives an average glucose from the A(1c) result. Herein, we review A(1c) , the components involved in A(1c) formation, and the interindividual and assay variations that can lead to differences in A(1c) results, despite comparable glycemic control. We discuss the proposed introduction of ADAG as a surrogate for A(1c) reporting, review imprecisions that may result, and suggest alternative clinical approaches.