The general use of glycated haemoglobin for the diagnosis of diabetes and other categories of glucose intolerance: still a long way to go

Microfluidic-based systems for the management of diabetes

Diabetes currently affects approximately 500 million people worldwide and is one of the most common causes of mortality in the United States. To diagnose and monitor diabetes, finger-prick blood glucose testing has long been used as the clinical gold standard. For diabetes treatment, insulin is typically delivered subcutaneously through cannula-based syringes, pens, or pumps in almost all type 1 diabetic (T1D) patients and some type 2 diabetic (T2D) patients. These painful, invasive approaches can cause non-adherence to glucose testing and insulin therapy. To address these problems, researchers have developed miniaturized blood glucose testing devices as well as microfluidic platforms for non-invasive glucose testing through other body fluids. In addition, glycated hemoglobin (HbA1c), insulin levels, and cellular biomechanics-related metrics have also been considered for microfluidic-based diabetes diagnosis. For the treatment of diabetes, insulin has been delivered transdermally through microdevices, mostly through microneedle array-based, minimally invasive injections. Researchers have also developed microfluidic platforms for oral, intraperitoneal, and inhalation-based delivery of insulin. For T2D patients, metformin, glucagon-like peptide 1 (GLP-1), and GLP-1 receptor agonists have also been delivered using microfluidic technologies. Thus far, clinical studies have been widely performed on microfluidic-based diabetes monitoring, especially glucose sensing, yet technologies for the delivery of insulin and other drugs to diabetic patients with microfluidics are still mostly in the preclinical stage. This article provides a concise review of the role of microfluidic devices in the diagnosis and monitoring of diabetes, as well as the delivery of pharmaceuticals to treat diabetes using microfluidic technologies in the recent literature.

Glucose Disorders

Glucose disorders are the most common endocrine condition in the primary care setting. The conditions overlap and are better viewed as a spectrum rather than discrete entities. Multiple treatment agents are now available for diabetes mellitus which include long-acting and short-acting insulins and medications targeting the various pathways of diabetes including liver gluconeogenesis, increasing peripheral insulin sensitivity, stimulating pancreatic insulin production, eliminating glucose renally, decreasing carbohydrate gastrointestinal absorption, and targeting the body's incretin system. Various endocrine conditions can cause secondary hyperglycemia or hypoglycemia. Medications and physiologic stress can affect glucose levels. Genetic syndromes causing enzyme deficiencies underlie a small portion of glucose disorders.

Implementing care for women with gestational diabetes after delivery-the challenges ahead

Gestational diabetes (GDM), defined as glucose intolerance during pregnancy, affects one in six pregnancies globally and significantly increases a woman's lifetime risk of type 2 diabetes mellitus (T2DM). Being a relatively young group, women with GDM are also at higher risk of developing diabetes related complications (e.g., cardiovascular disease, non-alcoholic fatty liver disease) later in life. Children of women with GDM are also likely to develop GDM and this perpetuates a cycle of diabetes, escalating our current pandemic of metabolic disease. The global prevalence of GDM has now risen by more than 30% over the last two decades, making it an emerging public health concern. Antepartum management of maternal glucose is unable to fully mitigate the associated lifetime cardiometabolic risk. Thus, efforts may need to focus on improving care for women with GDM during the postpartum period where prevention or therapeutic strategies could be implemented to attenuate progression of GDM to DM and its associated vascular complications. However, strategies to provide care for women in the postpartum period often showed disappointing results. This has led to a missed opportunity to halt the progression of impaired glucose tolerance/impaired fasting glucose to DM in women with GDM. In this review, we examined the challenges in the management of women with GDM after delivery and considered how each of these challenges are defined and could present as a gap in translating evidence to clinical care. We highlighted challenges related to postpartum surveillance, postpartum glucose testing strategies, postpartum risk factor modification, and problems encountered in engagement of patients/providers to implement interventions strategies in women with GDM after delivery. We reasoned that a multisystem approach is needed to address these challenges and to retard progression to DM and cardiovascular disease (CVD) in women with GDM pregnancies. This is very much needed to pave way for an improved, precise, culturally sensitive and wholistic care for women with GDM.

Repeated Dry Sauna Therapy Improves Quality of Life in Obese Korean People

Background

Dry sauna treatments improve the quality of life for chronic pain, congestive heart failure, and type 2 diabetes patients. This study aimed to determine whether dry sauna therapy improved the quality of life of obese people.

Methods

A total of 38 consecutive participants aged over 20 years with a body mass index of ≥25 kg/m² were recruited for the study. The participants were treated with a 90°C dry sauna for 15 minutes, twice daily for 4 consecutive days. To assess the quality of life, all participants completed the 5 level EQ-5D questionnaires and the EQ-Visual Analog Scale. Study parameters were measured on the same day prior to commencing the sauna sessions in a fasted state and 2 days after the last sauna session.

Results

The average age was 62.3±9.5 years; 84.2% of the participants were female. The mean body mass index was 28.5±2.4 kg/m². Dry sauna significantly improved the mean 5 level EQ-5D index scores from 0.83±0.12 to 0.89±0.11 and increased the mean EQ-Visual Analog Scale from 79.0±15.2 to 91.1±9.7. However, there were no significant changes in body mass index, blood pressure, heart rate, or body composition before and after the 8-session sauna therapy.

Conclusion

Dry sauna improved the health-related quality of life of obese patients without adverse events. Further clinical studies in larger study populations are needed to verify these findings and provide concrete evidence for obesity treatment.

The analytical performance of laboratory plasma glucose and HbA1c measurements are largely acceptable

AIMS

Poor comparability between laboratory results may have a strong impact on clinical decisions. The aim of this study was to assess the quality of glucose and HbA_1c measurements in a large cohort of laboratories in various countries, in order to evaluate whether the current state of these very basic laboratory examinations can be considered to be adequate with respect to the clinical needs in the management of glucose control in diabetic patients.

METHODS

External quality assessment schemes and proficiency testing surveys performed in 2017 in several European and American laboratories were analyzed in order to estimate the percentage of laboratories reaching the desired quality criteria based on the allowable total error in accordance with various international recommendations.

RESULTS

In 2017 more than 95% of laboratories met the allowable total error for measuring HbA_1c, and 92-94% of the studied laboratories met the target for glucose measurement.

CONCLUSIONS

The analytical quality for measuring glycated hemoglobin and glucose at laboratory level is generally acceptable, and accreditation to the ISO 15189:2012 standard is a robust guarantee that the laboratory meets the required criteria of acceptability. Several pre-analytical factors which may explain the discrepancies between the measured HbA_1c and that estimated from other indicators of glucose control have to be taken into account, by focusing more on the pre-analytical than the analytical phase. In the case of glucose, special attention should be paid to the use of the correct anticoagulant, in order to avoid false negative results.

Labile haemoglobin as a glycaemic biomarker for patient-specific monitoring of diabetes: mathematical modelling approach

Diabetes mellitus constitutes a major health problem and its clinical presentation and progression may vary considerably. A number of standardized diagnostic and monitoring tests are currently used for diabetes. They are based on measuring either plasma glucose, glycated haemoglobin or both. Their main goal is to assess the average blood glucose concentration. There are several sources of interference that can lead to discordances between measured plasma glucose and glycated haemoglobin levels. These include haemoglobinopathies, conditions associated with increased red blood cell turnover or the administration of some therapies, to name a few. Therefore, there is a need to provide new diagnostic tools for diabetes that employ clinically accessible biomarkers which, at the same time, can offer additional information allowing us to detect possible conflicting cases and to yield more reliable evaluations of the average blood glucose level concentration. We put forward a biomathematical model to describe the kinetics of two patient-specific glycaemic biomarkers to track the emergence and evolution of diabetes: glycated haemoglobin and its labile fraction. Our method incorporates erythrocyte age distribution and utilizes a large cohort of clinical data from blood tests to support its usefulness for diabetes monitoring.

Effects of hemoglobin variants HbJ Bangkok, HbE, HbG Taipei, and HbH on analysis of glycated hemoglobin via ion-exchange high-performance liquid chromatography

BACKGROUND

To explore the effects of HbJ Bangkok, HbE, HbG Taipei, and α-thalassemia HbH on the results of HbA1c assessment using ion-exchange high-performance liquid chromatography (IE-HPLC).

METHODS

We enrolled five patients in which the results of the IE-HPLC HbA1c assay were inconsistent with the average levels of FBG. We performed hemoglobin capillary (Hb) electrophoresis using whole-blood samples. We also sequenced the genes encoding Hb using dideoxy-mediated chain termination and analyzed HbA1c using borate affinity HPLC (BA-HPLC) and turbidimetric inhibition immunoassay (TINIA).

RESULTS

Two patients had the HbJ Bangkok variant. Hb genotypes of these patients were β^41-42 /β^{J Bangkok} and β^N /β^{J Bangkok} , and the content of HbJ Bangkok was 93.9% and 52.4%, respectively. The remaining three patients had the following: HbE (β^N /β^E Hb genotype, 23.6% HbE content), HbG Taipei (β^N /β^{G Taipei} Hb genotype, 39.4% HbG Taipei content), and α-thalassemia HbH (6.1% HbH content, 2.8% Hb Bart's content). In the patients with β-thalassemia and HbJ Bangkok variants, the presence of the variants interfered with the results of HbA1c analyses using IE-HPLC and TINIA; in the remaining four patients, there was interference with the results of HbA1c IE-HPLC but not with the TINIA assay. There was no interference with BA-HPLC HbA1c results.

CONCLUSIONS

HbJ Bangkok, HbE, HbG Taipei Hb, and α-thalassemia HbH disease cause varying degrees of interference with the analysis of HbA1c using IE-HPLC. In these patients, we suggest using methods free from such interference for the analysis of HbA1c and other indicators to monitor blood glucose levels.

Circulating linoleic acid and alpha-linolenic acid and glucose metabolism: the Hoorn Study

PURPOSE

Data on the relation between linoleic acid (LA) and alpha-linolenic acid (ALA) and type 2 diabetes mellitus (T2DM) risk are scarce and inconsistent. The aim of this study was to investigate the association of serum LA and ALA with fasting and 2 h post-load plasma glucose and glycated hemoglobin (HbA1c).

METHOD

This study included 667 participants from third examination (2000) of the population-based Hoorn study in which individuals with glucose intolerance were overrepresented. Fatty acid profiles in serum total lipids were measured at baseline, in 2000. Diabetes risk markers were measured at baseline and follow-up in 2008. Linear regression models were used in cross-sectional and prospective analyses.

RESULTS

In cross-sectional analyses (n = 667), serum LA was inversely associated with plasma glucose, both in fasting conditions (B = -0.024 [-0.045, -0.002]) and 2 h after glucose tolerance test (B = -0.099 [-0.158, -0.039]), but not with HbA1c (B = 0.000 [-0.014, 0.013]), after adjustment for relevant factors. In prospective analyses (n = 257), serum LA was not associated with fasting (B = 0.003 [-0.019, 0.025]) or post-load glucose (B = -0.026 [-0.100, 0.049]). Furthermore, no significant associations were found between serum ALA and glucose metabolism in cross-sectional or prospective analyses.

CONCLUSIONS

In this study, serum LA was inversely associated with fasting and post-load glucose in cross-sectional, but not in prospective analyses. Further studies are needed to elucidate the exact role of serum LA and ALA levels and dietary polyunsaturated fatty acids in glucose metabolism.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

Glycated albumin is superior to glycated hemoglobin for glycemic control assessment at an early stage of diabetes treatment: A multicenter, prospective study

AIMS

This study was to determine whether serum glycated albumin (GA) was a better indicator of glycemic control than hemoglobin A1c (HbA1c) when starting a new treatment regimen for type 2 diabetes.

METHODS

Newly diagnosed type 2 diabetes patients, or patients who had poor glycemic control with oral hypoglycemic agents, were enrolled at 10 hospitals in Beijing. Serum GA, HbA1c, fasting blood glucose (FBG), and C-peptide were assayed on Days 0, 14, 28, and 91 after treatment.

RESULTS

Four hundred ninety-nine patients were enrolled. Mean FBG, GA and HbA1c decreased significantly in patients at Days 14, 28, and 91. In patients with improved glycemic control, the reduction of GA and HbA1c levels was 10.5±13.3% vs. 5.1±5.4% on Day 14, 16.0±13.4% vs. 9.0±7.0% on Day 28, and 18.0±16.7% vs. 18.3±9.4% on Day 91, respectively, compared with baseline values. Changes in GA on Day 14, 28 and 91 were all closely correlated with changes in HbA1c on Day 91. Change in GA on Day 14 was correlated with treatment effectiveness evaluated by HbA1c on Day 91.

CONCLUSIONS

GA may be a useful marker for assessing glycemic control at an early stage of new diabetes treatment and assist in guiding adjustments to treatment and therapy.

Methods, units and quality requirements for the analysis of haemoglobin A1c in diabetes mellitus

The formation of glycohemoglobin, especially the hemoglobin A_1c (HbA_1c) fraction, occurs when glucose becomes coupled with the amino acid valine in the β-chain of Hb; this reaction is dependent on the plasma concentration of glucose. Since the early 1970s it has been known that diabetics display higher values OF HbA_1C because they have elevated blood glucose concentrations. Thus HbA_1c has acquired a very important role in the treatment and diagnosis of diabetes mellitus. After the introduction of the first quantitative measurement OF HbA_1C, numerous methods for glycohemoglobin have been introduced with different assay principles: From a simple mini-column technique to the very accurate automated high-pressure chromatography and lastly to many automated immunochemical or enzymatic assays. In early days, the results of the quality control reports for HbA_1c varied extensively between laboratories, therefore in United States and Canada working groups (WG) of the Diabetes Controls and Complications Trial (DCCT) were set up to standardize the HbA_1c assays against the DCCT/National Glycohemoglobin Standardization Program reference method based on liquid chromatography. In the 1990s, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) appointed a new WG to plan a reference preparation and method for the HBA_1c measurement. When the reference procedures were established, in 2004 IFCC recommended that all manufacturers for equipment used in HbA_1c assays should calibrate their methods to their proposals. This led to an improvement in the coefficient of variation (CV%) associated with the assay. In this review, we describe the glycation of Hb, methods, standardization of the HbA_1c assays, analytical problems, problems with the units in which HbA_1c values are expressed, reference values, quality control aspects, target requirements for HbA_1c, and the relationship of the plasma glucose values to HbA_1c concentrations. We also note that the acceptance of the mmol/mol system for HbA_1c as recommended by IFCC, i.e., the new unit and reference ranges, are becoming only slowly accepted outside of Europe where it seems that expressing HbA_1c values either only in per cent units or with parallel reporting of percent and mmol/mol will continue. We believe that these issues should be resolved in the future and that it would avoid confusion if mmol/mol unit for HbA_1c were to gain worldwide acceptance.

Evaluation of Bio-Rad D-100 HbA1c analyzer against Tosoh G8 and Menarini HA-8180V

Objectives

To evaluate the Bio-Rad D-100®, an HPLC analyzer for glycated hemoglobin (HbA_1c) determination, and to compare its performance with the Menarini HA-8180V® and Sysmex G8®.

Methods

Method comparison was performed according to Clinical and Laboratory Standards Institute (CLSI) EP9-A2 guidelines. We selected 100 samples from the routine laboratory workload and analyzed them in duplicate with the three analyzers. The imprecision study was performed according to CLSI EP5-A2 guidelines for both inter-assay and intra-assay variability. Bias was assessed with external quality control material. To establish linearity, CLSI EP6-A protocol was followed.

Results

Method comparison (95% confidence intervals in parentheses): D-100 vs G8: Passing-Bablok regression; y=0.973(0.963–0.983)×−0.07(−0.07−0.069); r=0.9989. Bland-Altman mean difference: −0.229%HbA_1c (−0.256: −0.202); Relative bias plot: D-100/G8 vs D100-G8 mean ratio=0.971(0.967−0.975). D-100 vs HA-8180V: Passing-Bablok regression; y=0.944(0.932–0.958)×−0.078(0.024−0.173); r=0.9989. Bland-Altman mean difference: −0.363%HbA_1c (−0.401: −0.325); Relative bias plot D-100/HA-8180V vs D100-HA-8180V mean ratio=0.955(0.952−0.958). Inter-assay coefficient of variation (CV): 0.81%. Intra-assay CV: 1.04% (low level), and 0.78% (high level). Bias against target value=2.332%. Linearity: r²=0.998 in the concentration range 4.4−13.9%HbA_1c. Carry-over: 0.0024%.

Conclusions

The Bio-Rad D-100 shows good correlation with G8 and HA-8180V. There is a small proportional systematic difference (2.7% and 5.6%, respectively) in both comparisons. Inter and intra-assay CVs are both lower than the lowest CV obtained in studies performed with D-100 and other instruments.

Implications of using HBA1C as a diagnostic marker for diabetes

Diagnosing diabetes now includes a new criterion; hemoglobin A1_C ≥6.5 % which can have significant implications. This review compares the advantages and disadvantages of using HbA1_C as the main diabetic diagnostic test. HbA1_C has greater stability and less variability than plasma glucose measurements but may not always reflect glycemic levels of glycaemia. The present cut off value identifies fewer diabetics than glucose-based criteria. HbA1_C being more convenient could diagnose more patients but this is not yet proven. When choosing a diagnostic test, the limitations of each test must be clearly understood to use appropriate clinical judgment and consider patient preference.

Fructosamine is a risk factor for myocardial infarction and all-cause mortality - Longitudinal experience from the AMORIS cohort

BACKGROUND AND AIMS

Glycation is linked to microvascular complications of diabetes and also to macrovascular events. Fructosamine is a biomarker of glycation but its associations to macrovascular complications are not well documented. The aim of this study was to evaluate fructosamine as a predictor of myocardial infarction and all-cause mortality in a large population based cohort.

METHODS AND RESULTS

Information on glucose and fructosamine was obtained from subjects of the AMORIS cohort (n = 338,443) followed for 19 years on average. Incident cases of myocardial infarction and death from any cause were identified from national patient and cause of death register respectively. The incidence of myocardial infarction (n = 21,526 cases) and all-cause mortality (n = 73,458 deaths) increased at a fructosamine of 2.30 mmol/L or above. For myocardial infarction, the sex-age- fasting- and entry period adjusted hazard ratio in subjects above 2.70 mmol/L vs. reference range subjects was 2.88 (95% CI: 2.70-3.07). The corresponding hazard ratio for all-cause mortality was 2.31 (95% CI: 2.21-2.41). These associations remained basically unchanged after adjustment for total cholesterol, triglycerides, albumin, social class, smoking and hypertension. When additional adjustment for glucose was performed the associations were attenuated but remained. In a sub cohort with simultaneous measurements of fructosamine, HbA1c and fasting glucose respectively similar associations were observed (n = 9746).

CONCLUSION

There is a strong association between fructosamine and myocardial infarction and death from any cause when major cardiovascular risk factors are accounted for. In addition, this association could only partly be explained by glucose levels.

HbA1c alone is a poor indicator of cardiometabolic risk in middle-aged subjects with pre-diabetes but is suitable for type 2 diabetes diagnosis: a cross-sectional study

Objectives

Glycated haemoglobin A_1c (HbA_1c) measurement is recommended as an alternative to fasting plasma glucose (FPG) for the diagnosis of pre-diabetes and type 2 diabetes. However, evidence suggests discordance between HbA_1c and FPG. In this study we examine a range of metabolic risk features, pro-inflammatory cytokines, acute-phase response proteins, coagulation factors and white blood cell counts to determine which assay more accurately identifies individuals at increased cardiometabolic risk.

Materials and Methods

This was a cross-sectional study involving a random sample of 2,047 men and women aged 46-73 years. Binary and multinomial logistic regression were employed to examine risk feature associations with pre-diabetes [either HbA_1c levels 5.7-6.4% (39-46 mmol/mol) or impaired FPG levels 5.6-6.9 mmol/l] and type 2 diabetes [either HbA_1c levels >6.5% (>48 mmol/mol) or FPG levels >7.0 mmol/l]. Receiver operating characteristic curve analysis was used to evaluate the ability of HbA_1c to discriminate pre-diabetes and diabetes defined by FPG.

Results

Stronger associations with diabetes-related phenotypes were observed in pre-diabetic subjects diagnosed by FPG compared to those detected by HbA_1c. Individuals with type 2 diabetes exhibited cardiometabolic profiles that were broadly similar according to diagnosis by either assay. Pre-diabetic participants classified by both assays displayed a more pro-inflammatory, pro-atherogenic, hypertensive and insulin resistant profile. Odds ratios of having three or more metabolic syndrome features were also noticeably increased (OR: 4.0, 95% CI: 2.8-5.8) when compared to subjects diagnosed by either HbA_1c (OR: 1.4, 95% CI: 1.2-1.8) or FPG (OR: 3.0, 95% CI: 1.7-5.1) separately.

Conclusions

In middle-aged Caucasian-Europeans, HbA_1c alone is a poor indicator of cardiometabolic risk but is suitable for diagnosing diabetes. Combined use of HbA_1c and FPG may be of additional benefit for detecting individuals at highest odds of type 2 diabetes development.

Right Dorsolateral Frontal Lobe N-Acetyl Aspartate and Myoinositol Concentration Estimation in Type 2 Diabetes with Magnetic Resonance Spectroscopy

INTRODUCTION

Chronic hyperglycaemia in type 2 diabetes, effects the central nervous system by altering the concentrations of brain metabolites like N-acetyl aspartate (NAA) and myoinositol (mI), which are indicators of neuronal integrity and glial cell damage respectively. Dorsolateral frontal lobe is associated with aspects of cognition especially right frontal lobe is involved in episodic memory retrieval, ninety percent of the diabetic cases are type 2 in nature globally and yoga is very effective in stabilizing the brain metabolites by bringing the blood glucose levels to near or within the physiological range in type 2 diabetes.

AIM AND OBJECTIVES

The aim of the study was to observe the effects of yogasana and pranayama on glycosilated haemoglobin (HbA1c) levels and right dorsolateral frontal cortical NAA and mI concentration in type 2 diabetic subjects.

MATERIALS AND METHODS

It's a case control study. Sixty eight type 2 diabetic subjects of both the sex, aged between 35-65 years are included in the study, subjects are divided in to test and control group 34 each. Test group subjects did the yogasana and pranayama for a period of 6 months, 6 days in a week, 45-60 minutes daily under the supervision of a qualified yoga teacher. Control group subjects are not on any specific exercise regimen. Both the group subjects are taking oral hypoglycaemic agents. HbA1c levels are measured using the Bio-Rad D-10™ haemoglobin A1c program and Magnetic Resonance Spectroscopy (MRS) is used in assessing the metabolite concentrations.

STATISTICAL ANALYSIS

Analysis of data was done by using unpaired t-test. P-value for HbA1c level is <0.001, which is highly significant statistically. P-value for NAA was < 0.02 and for myoinositol was < 0.01, which are statistically significant.

RESULTS

HbA1c levels in control and test group subjects are 7.7 ± 1.84 and 6.02 ± 0.46 respectively. NAA concentrations in the right dorsolateral frontal lobe of control and test group are 1.44 ± 0.15 and 1.54 ± 0.19 respectively. The mI concentrations in the right dorsolateral frontal lobe of control and test group are 0.61 ± 0.22 and 0.47 ± 0.24 respectively.

CONCLUSION

Yogasana and pranayama minimized the neuronal and glial cellular damage in test group, which is evident by minimal changes in right dorsolateral frontal lobe NAA and mI levels in type 2 diabetic subjects.

Dysglycemia and long-term mortality: observations from the Israel study of glucose intolerance, obesity and hypertension

BACKGROUND

We describe the relationship between dysglycemia and long-term mortality and elucidate the relationship between blood glucose levels during an oral glucose tolerance test (OGTT) and haemoglobin A1 (HbA1) and mortality.

METHODS

A cohort of 1410 individuals was followed for 33 years since 1980. Fasting and post-OGTT glucose parameters were used to categorize the cohort according to baseline glycemic status.

RESULTS

The mortality rate increased from 43% in normoglycemic individuals to 53.3, 61.7, 72.9 and 88.0% in those with impaired fasting glucose (IFG), impaired glucose tolerance (IGT), IFG/IGT and diabetes, respectively. The highest mortality rate, compared with the normoglycemic category, was observed in individuals with IFG/IGT and diabetes according to a Cox proportional hazard model (HR = 1.38, 95%CI 1.10-1.74 and HR = 2.14, 95%CI 1.70-2.70, respectively), followed by individuals with IGT and IFG, but this did not reach statistical significance. We speculate that the IFG group may represent a mixture of individuals en route from normal to the next two categories as well as another cohort whose glucose levels are stably set at the upper reaches of the normal distribution. Significant differences were found between 1 and 2 h glucose values (p < 0.001). Fasting, 60 and 120 min glucose values were positively associated with increasing HbA1 quintiles (p < 0.05). The mean HbA1 was significantly higher in those who died (p = 0.01). The highest mortality (58.8%) was observed in the upper HbA1 quintile that was also associated with the highest prevalence of the metabolic syndrome (17.2%).

CONCLUSIONS

This study shows a continuous relationship between the severity of dysglycemia and long-term mortality and should promote the early recognition of prediabetes. The 1 h post-load glucose level was continuously associated with increasing HbA1 concentrations and may therefore serve as an early marker for abnormalities in glucose tolerance. An elevated 1 h post-load glucose level may potentially identify at-risk individuals well before the traditional 2 h glucose value.

Association of pre-pregnancy BMI and postpartum weight retention with postpartum HbA1c among women with Type 1 diabetes

AIM

To examine the association of pre-pregnancy BMI and postpartum weight retention with postpartum HbA(1c) levels in women with Type 1 diabetes.

METHODS

We longitudinally evaluated 136 women with Type 1 diabetes who received prenatal, pregnancy, and postpartum care through Joslin Diabetes Center's Diabetes and Pregnancy Program between 2004 and 2009. Weight, BMI and HbA(1c) concentrations were assessed before the index pregnancy and repeatedly monitored after delivery until 12 months postpartum. We used linear mixed models to assess the association of postpartum HbA(1c) with pre-pregnancy BMI and postpartum weight retention.

RESULTS

The mean HbA(1c) concentration increased from 49 mmol/mol (6.6%) at 6 weeks postpartum to 58 mmol/mol (7.5%) by 10 months postpartum, a level similar to the mean pre-pregnancy HbA(1c) concentration. Postpartum weight retention showed a linearly decreasing trend of 0.06 kg/week (P < 0.0001), with -0.1 kg average postpartum weight retention by 1 year postpartum. Compared with women with a pre-pregnancy BMI ≥ 25 kg/m², women with a lower pre-pregnancy BMI maintained a 3.4 mmol/mol (0.31%) lower HbA(1c) concentration, after adjusting for several sociodemographic, reproductive and diabetes-related factors (P = 0.03). There was a suggestion of a time-varying positive association between HbA1c and postpartum weight retention, with the most significant difference of 3.7 mmol/mol (0.34%; P = 0.05) at 30 weeks postpartum among women with postpartum weight retention ≥ 5 kg vs those with postpartum weight retention < 5 kg.

CONCLUSIONS

Pre-pregnancy BMI and postpartum weight retention were positively associated with HbA(1c) during the first postpartum year in women with Type 1 diabetes. Interventions to modify the behaviours associated with these body weight factors before pregnancy and after delivery may help women with Type 1 diabetes maintain good glycaemic control after pregnancy.

The Early Diabetes Intervention Program--is early actually late?

This Commentary briefly reviews the background of prediabetes including its definition and pathophysiology and describes as well the natural course of glycemic deterioration as it follows a continuum. Research efforts in identifying glucose and other biomarkers for the early detection of high-risk individuals are summarized.

Screening with HbA1c identifies only one in two individuals with diagnosis of prediabetes at oral glucose tolerance test: findings in a real-world Caucasian population

OBJECTIVE

Discordance between HbA1c and OGTT in screening pre-diabetes may occur because of lack of laboratory standardization, distinct underlying pathophysiological processes or different ethnicity. We evaluated HbA1c efficacy for screening OGTT-defined IFG and IGT conditions in a large Caucasian population using the newly revised IFCC protocol.

RESEARCH DESIGN AND METHODS

A total of 501 consecutive subjects were screened for pre-diabetic conditions with OGTT with 75 g of glucose. Testing for HbA1c, lipid profile and fasting insulin levels was also performed. For detecting differences between continuous variables, ANOVA followed by Tukey's honestly significant difference (HSD) post hoc test was used. Logistic regression and ROC curve analysis were also performed for assessing HbA1c screening efficacy.

RESULTS

ROC curve analysis showed that optimal HbA1c cut-off for detecting IFG was 5.6 % (sensitivity of 78 % and specificity of 63 %), while for IGT, the optimal cut-off was 5.9 % (sensitivity of 46 % and specificity of 84 %), with AUCs < 0.8. Screening with HbA1c identified 53.4 % of the 193 patients with IFG and/or IGT diagnosed at OGTT. As regards surrogate markers of insulin resistance, we observed a trend towards higher values of HOMA-IR and lower QUICKI values in subjects with IFG than in those with IGT. Patients with pre-diabetes at both tests had similar values of HOMA and QUICKI, compared with those with altered OGTT only.

CONCLUSIONS

IFCC-aligned HbA1c assay proved scarcely effective in detecting IFG and/or IGT in a large Caucasian population, identifying only half of the patients with abnormal OGTT. Moreover, adding HbA1c screening to OGTT may be of little benefit in identifying subjects with a worse metabolic profile.

Is early postpartum HbA1c an appropriate risk predictor after pregnancy with gestational diabetes mellitus?

Compared to the 2-h oral glucose tolerance test (OGTT), the assessment of HbA1c was proposed as a less time-consuming alternative to detect pathologies in carbohydrate metabolism. This report aims to assess the predictive accuracy of HbA1c to detect alterations in glucose disposition early after gestational diabetes mellitus (GDM) pregnancy. A detailed metabolic characterization was performed in 77 women with previous GDM (pGDM) and 41 controls 3-6 month after delivery: 3-h OGTT, frequently sampled intravenous glucose tolerance test. Follow-up examinations of pGDMs were performed up to 10 years. HbA1c (venous samples, HPLC) was assessed at baseline as well as during the follow-up period (475 patient contacts). Moderate associations were observed between HbA1c and measurements of plasma glucose during the OGTT at the baseline examination: The strongest correlation was found for FPG (r = 0.40, p < 0.001), decreasing after ingestion. No associations were detected between HbA1c and OGTT dynamics of insulin or C-peptide. Moreover, baseline HbA1c showed only modest correlation with insulin sensitivity (r = -0.25, p = 0.010) and disposition index (r = -0.26, p = 0.007). A linear model including fasting as well as post-load glucose levels was not improved by HbA1c. However, pGDM females with overt diabetes manifestation during the follow-up period showed more pronounced increasing HbA1c in contrast to females remaining normal glucose tolerant or developing prediabetes. It is suggested that the performance of HbA1c assessed early after delivery is inferior to the OGTT for the detection of early alterations in glucose metabolism. However, an increase in HbA1c levels could be used as an indicator of risk for diabetes manifestation.

Glycemic variability in normal glucose regulation subjects with elevated 1-h postload plasma glucose levels

Subjects with normal glucose regulation (NGR), whose 1-h postload plasma glucose is ≥8.6 mmol/L (155 mg/dL, NGR 1 h ≥ 8.6) during 75-g oral glucose tolerance test (OGTT), have an increased risk of type 2 diabetes and subclinical organ damage. And, the deficiency in islet β cell function is responsible for glycemic disorders. The purpose of this study is to investigate glycemic variability in NGR subjects with elevated 1-h postload plasma glucose levels and its association with islet β cell function. The 29 NGR subjects with 1-h postload plasma glucose ≥8.6 mmol/L (NGR 1 h ≥ 8.6) and 29 age- and sex-matched NGR subjects with 1-h postload plasma glucose <8.6 mmol/L (NGR 1 h < 8.6) were recruited in the study. Insulin sensitivity (Matsuda index, ISI), insulin secretion (insulinogenic index ΔI30/ΔG30), and integrated β cell function measured by the oral disposition index (ΔI30/ΔG30 multiplied by the ISI) were derived from OGTT. All subjects were monitored using the continuous glucose monitoring system for consecutive 72 h. The multiple parameters of glycemic variability included the standard deviation of blood glucose (SDBG), mean blood glucose (MBG), mean of daily differences (MODD), and mean amplitude of glycemic excursions (MAGE). MAGE is considered as a gold standard of glycemic variability. Glycemic variability parameters SDBG, MBG, MODD, and MAGE in NGR 1 h ≥ 8.6 group were higher than those in NGR 1 h < 8.6 group (p < 0.05), and oral disposition index in NGR 1 h ≥ 8.6 group was lower than that in NGR 1 h < 8.6 group (p < 0.05). SDBG, MBG, MODD, MAGE, and 1-h postload plasma glucose all negatively associated with oral disposition index in the separate group (p < 0.05) and in the whole subjects (p < 0.05). After multivariate regression analysis, oral disposition index was the strongest independent contributor to MAGE and 1-h postload plasma glucose in the separate group (p < 0.05) and in the whole subjects (p < 0.05). It is concluded that NGR 1 h ≥ 8.6 group had higher glycemic variability and lower oral disposition index, compared with NGR 1 h < 8.6 group. Increased glycemic variability parameters and elevated 1-h postload plasma glucose consistently associated with declined oral disposition index in subjects from NGR 1 h < 8.6 to NGR 1 h ≥ 8.6 group.

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

BACKGROUND

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

AIM OF STUDY

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

METHOD

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

RESULTS

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

CONCLUSION

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

Vitamin D status, incident diabetes and prospective changes in glucose metabolism in older subjects: the Hoorn study

BACKGROUND AND AIMS

Vitamin D deficiency may contribute to impaired glucose metabolism and type 2 diabetes, especially in the elderly population. We aimed to evaluate whether baseline 25-hydroxyvitamin D (25[OH]D) levels are prospectively associated with deterioration of glucose metabolism and the incidence of diabetes.

METHODS AND RESULTS

We examined a subsample from the population based Hoorn study among older men and women. Physical examinations were performed from 2000 to 2001 and included measurements of 25(OH)D. Glucose tolerance tests and HbA1c measurements were performed at baseline and at a follow-up between 2007 and 2009. We included 351 study participants (51% females; 67.9 ± 5.7 years). Baseline 25(OH)D levels were 56.7 ± 18.8 nmol/L and follow-up visits were performed after 7.5 ± 0.5 years. Among 280 study participants without diabetes at baseline we recorded 45 cases of incident diabetes. There was no significant association of 25(OH)D with the incidence of diabetes and with fasting and 2h postload glucose levels at follow-up. In analyses adjusted for age, sex, and baseline HbA1c there was, however, a significant association of 25(OH)D with follow-up HbA1c levels (beta coefficient=-0.085, p=0.085). This association was attenuated after further adjustments for BMI (beta coefficient=-0.079, p=0.064).

CONCLUSIONS

In this study among the older population we observed no significant association of baseline 25(OH)D with glucose metabolism and incident diabetes. We found, however, a non-significant trend towards an inverse association of 25(OH)D with prospective changes in HbA1c that deserves further investigations.

Hemoglobin A1c levels and aortic arterial stiffness: the Cardiometabolic Risk in Chinese (CRC) study

OBJECTIVE

The American Diabetes Association (ADA) recently published new clinical guidelines in which hemoglobin A1c (HbA1c) was recommended as a diagnostic test for diabetes. The present study was to investigate the association between HbA1c and cardiovascular risk, and compare the associations with fasting glucose and 2-hour oral glucose tolerance test (2 h OGTT).

RESEARCH DESIGN AND METHODS

The study samples are from a community-based health examination survey in central China. Carotid-to-femoral pulse wave velocity (cfPWV) and HbA1c were measured in 5,098 men and women.

RESULTS

After adjustment for age, sex, and BMI, the levels of HbA1c were significantly associated with an increasing trend of cfPWV in a dose-dependent fashion (P for trend <0.0001). The associations remained significant after further adjustment for blood pressure, heart rate, and lipids (P = 0.004), and the difference in cfPWV between the highest and the lowest quintiles of HbA1c was 0.31 m/s. Fasting glucose and 2 h OGTT were not associated with cfPWV in the multivariate analyses. HbA1c showed additive effects with fasting glucose or 2 h OGTT on cfPWV. In addition, age and blood pressure significantly modified the associations between HbA1c and cfPWV (P for interactions <0.0001 for age; and  = 0.019 for blood pressure). The associations were stronger in subjects who were older (≥60 y; P for trend = 0.004) and had higher blood pressure (≥120 [systolic blood pressure]/80 mmHg [diastolic blood pressure]; P for trend = 0.028) than those who were younger and had lower blood pressure (P for trend >0.05).

CONCLUSIONS

HbA1c was related to high cfPWV, independent of conventional cardiovascular risk factors. Senior age and high blood pressure might amplify the adverse effects of HbA1c on cardiovascular risk.

Controversies on how diabetes is diagnosed

PURPOSE OF REVIEW

To evaluate the controversial aspects of diabetes diagnosis.

RECENT FINDINGS

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

SUMMARY

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