Circulating 1,5-anhydroglucitol levels in adult patients with diabetes reflect longitudinal changes of glycemia: a U.S. trial of the GlycoMark assay

Effects of 1,5-anhydroglucitol on postprandial blood glucose and insulin levels and hydrogen excretion in rats and healthy humans

The inhibition by 1,5-anhydro-d-glucitol (1,5-AG) was determined on disaccharidases of rats and humans. Then, the metabolism and fate of 1,5-AG was investigated in rats and humans. Although 1,5-AG inhibited about 50 % of sucrase activity in rat small intestine, the inhibition was less than half of d-sorbose. 1,5-AG strongly inhibited trehalase and lactase, whereas d-sorbose inhibited them very weakly. 1,5-AG noncompetitively inhibited sucrase. The inhibition of 1,5-AG on sucrase and maltase was similar between humans and rats. 1,5-AG in serum increased 30 min after oral administration of 1,5-AG (600 mg) in rats, and mostly 100 % of 1,5-AG was excreted into the urine 24 h after administration. 1,5-AG in serum showed a peak 30 min after ingestion of 1,5-AG (20 g) by healthy subjects, and decreased gradually over 180 min. About 60 % of 1,5-AG was excreted into the urine for 9 h following ingestion. Hydrogen was scarcely excreted in both rats and humans 24 h after administration of 1,5-AG. Furthermore, 1,5-AG significantly suppressed the blood glucose elevation, and hydrogen excretion was increased following the simultaneous ingestion of sucrose and 1,5-AG in healthy subjects. 1,5-AG also significantly suppressed the blood glucose elevation following the simultaneous ingestion of glucose and 1,5-AG; however, hydrogen excretion was negligible. The available energy of 1,5-AG, which is absorbed readily from the small intestine and excreted quickly into the urine, is 0 kJ/g (0 kcal/g). Furthermore, 1,5-AG might suppress the blood glucose elevation through the inhibition of sucrase, as well as intestinal glucose absorption.

A computational model of 1,5-AG dynamics during pregnancy

The importance of 1,5‐anhydroglucitol (1,5‐AG) as an intermediate biomarker for diabetic pregnancy is multi‐fold: (1) it serves as a reliable indicator of moderate‐level glycemic control, especially during early gestation; (2) it has been associated with increased risk of diabetes, independent of HbA1c and fasting glucose; and (3) it is an independent risk factor for the development of eclampsia during pregnancy. However, the clinical use of this biomarker during pregnancy has been underutilized due to physiological changes in glomerular filtration rate, plasma volume, and other hemodynamic parameters which have been hypothesized to bias gestational serum 1,5‐AG concentrations. Here, we develop an in‐silico model of gestational 1,5‐AG by combining pre‐existing physiological data in the literature with a two‐compartment mathematical model, building off of a previous kinetic model described by Stickle and Turk (1997) Am. J. Physiol., 273, E821. Our model quantitatively characterizes how renal and hemodynamic factors impact measured 1,5‐AG during normal pregnancy and during pregnancy with gestational diabetes and diabetes mellitus. During both normal and diabetic pregnancy, we find that a simple two‐compartment model of 1,5‐AG kinetics, with all parameters but reabsorption fraction adjusted for time in pregnancy, efficiently models 1,5‐AG kinetics throughout the first two trimesters. Allowing reabsorption fraction to decrease after 25 weeks permits parameters closer to expected physiological values during the last trimester. Our quantitative model of 1,5‐AG confirms the involvement of hypothesized renal and hemodynamic mechanisms during pregnancy, clarifying the expected trends in 1,5‐AG to aid clinical interpretation. Further research and data may elucidate biological changes during the third trimester that account for the drop in 1,5‐AG concentrations, and clarify physiological differences between diabetes subtypes during pregnancy.

A single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in type 2 diabetes mellitus

AIMS

SGLT2 inhibitors are a new class of oral hypoglycemic agents used in type 2 diabetes (T2DM). Their effectiveness in maturity onset diabetes of the young (MODY) is unknown. We aimed to assess the response to a single dose of 10 mg dapagliflozin in patients with Hepatocyte Nuclear Factor 1 Alpha (HNF1A)-MODY, Glucokinase (GCK)-MODY, and type 2 diabetes.

METHODS

We examined 14 HNF1A-MODY, 19 GCK-MODY, and 12 type 2 diabetes patients. All studied individuals received a single morning dose of 10 mg of dapagliflozin added to their current therapy of diabetes. To assess the response to dapagliflozin we analyzed change in urinary glucose to creatinine ratio and serum 1,5-Anhydroglucitol (1,5-AG) level.

RESULTS

There were only four patients with positive urine glucose before dapagliflozin administration (one with HNF1A-MODY, two with GCK-MODY, and one with T2DM), whereas after SGLT-2 inhibitor use, glycosuria occurred in all studied participants. Considerable changes in mean glucose to creatinine ratio after dapagliflozin administration were observed in all three groups (20.51 ± 12.08, 23.19 ± 8.10, and 9.84 ± 6.68 mmol/mmol for HNF1A-MODY, GCK-MODY, and T2DM, respectively, p < 0.001 for all comparisons). Post-hoc analysis revealed significant differences in mean glucose to creatinine ratio change between type 2 diabetes and each monogenic diabetes in response to dapagliflozin (p = 0.02, p = 0.003 for HNF1-A and GCK MODY, respectively), but not between the two MODY forms (p = 0.7231). Significant change in serum 1,5-AG was noticed only in T2DM and it was -6.57 ± 7.34 mg/ml (p = 0.04).

CONCLUSIONS

A single dose of dapagliflozin, an SGLT-2 inhibitor, induces higher glycosuria in GCK- and HNF1A-MODY than in T2DM. Whether flozins are a valid therapeutic option in these forms of MODY requires long-term clinical studies.

Comparison of insulin lispro mix 25 with insulin lispro mix 50 as insulin starter in Chinese patients with type 2 diabetes mellitus (CLASSIFY study): Subgroup analysis of a Phase 4 open-label randomized trial

BACKGROUND

Premixed insulins are recommended starter insulins in Chinese patients after oral antihyperglycemic medication (OAM) failure. In the present study, we compared the efficacy and safety of insulin lispro mix 25 (LM25) twice daily (b.i.d.) and insulin lispro mix 50 (LM50) b.i.d. as a starter insulin regimen in Chinese patients with type 2 diabetes mellitus (T2DM) who had inadequate glycemic control with OAMs.

METHODS

The primary efficacy outcome in the present open-label parallel randomized clinical trial was change in HbA1c from baseline to 26 weeks. Patients were randomized in a ratio of 1:  1 to LM25 (n = 80) or LM50 (n = 76). A mixed-effects model with repeated measures was used to analyze continuous variables. The Cochran-Mantel-Haenszel test with stratification factor was used to analyze categorical variables.

RESULTS

At the end of the study, LM50 was more efficacious than LM25 in reducing mean HbA1c levels (least-squares [LS] mean difference 0.48; 95 % confidence interval [CI] 0.22, 0.74; P < 0.001). More subjects in the LM50 than LM25 group achieved HbA1c targets of <7.0 % (72.4 % vs 45.0 %; P = 0.001) or ≤6.5 % (52.6 % vs 20.0 %; P < 0.001). Furthermore, LM50 was more effective than LM25 at reducing HbA1c in patients with baseline HbA1c, blood glucose excursion, and postprandial glucose greater than or equal to median levels (P ≤ 0.001). The rate and incidence of hypoglycemic episodes and increase in weight at the end of the study were similar between treatment groups.

CONCLUSIONS

In Chinese patients with T2DM, LM50 was more efficacious than LM25 as a starter insulin.

Serum 1,5-anhydroglucitol levels slightly increase rather than decrease after a glucose load in subjects with different glucose tolerance status

AIMS

Previous studies showed that serum 1,5-anhydroglucitol (1,5-AG) levels are significantly reduced in patients with diabetes mellitus (DM). However, it remains unclear how 1,5-AG levels acutely change in response to a glucose load. This study explored acute changes in 1,5-AG levels after a glucose load and the related influencing factors in individuals with differing degrees of glucose tolerance.

METHODS

A total of 681 participants (353 without DM and 328 with DM) without a prior history of DM were enrolled. All participants underwent an oral glucose tolerance test. Fasting and postload (30, 60, 120, and 180 min) levels of plasma glucose, serum 1,5-AG, and insulin were measured.

RESULTS

In all participant groups, serum 1,5-AG levels were slightly elevated after a glucose load and reached peak values at 120 min after loading (all P < 0.05). Regression analysis showed that body weight was negatively associated with the difference between peak and baseline 1,5-AG levels (Δ1,5-AG, standardized β = -0.119, P < 0.01). A strong and positive association between 1,5-AG₀ and Δ1,5-AG was also found independent of other confounding factors (standardized β = 0.376, P < 0.01). The ratio of the Δ1,5-AG to the 1,5-AG₀ was higher in DM patients (7.3% [3.4-11.5%]) than in those without DM (6.2% [3.6-9.2%]).

CONCLUSIONS

In contrast to the established decline in 1,5-AG levels with long-term hyperglycemia, the present study showed that serum 1,5-AG levels slightly increased by 6-7% after a glucose load. Further studies in different 1,5-AG transport models are needed to investigate the relevant metabolic pathways.

Whole-genome sequencing identifies common-to-rare variants associated with human blood metabolites

Genetic factors modifying the blood metabolome have been investigated through genome-wide association studies (GWAS) of common genetic variants and through exome sequencing. We conducted a whole-genome sequencing study of common, low-frequency and rare variants to associate genetic variations with blood metabolite levels using comprehensive metabolite profiling in 1,960 adults. We focused the analysis on 644 metabolites with consistent levels across three longitudinal data collections. Genetic sequence variations at 101 loci were associated with the levels of 246 (38%) metabolites (P ≤ 1.9 × 10^-11). We identified 113 (10.7%) among 1,054 unrelated individuals in the cohort who carried heterozygous rare variants likely influencing the function of 17 genes. Thirteen of the 17 genes are associated with inborn errors of metabolism or other pediatric genetic conditions. This study extends the map of loci influencing the metabolome and highlights the importance of heterozygous rare variants in determining abnormal blood metabolic phenotypes in adults.

Metabolomics based markers predict type 2 diabetes in a 14-year follow-up study

BACKGROUND

The growing field of metabolomics has opened up new opportunities for prediction of type 2 diabetes (T2D) going beyond the classical biochemistry assays.

OBJECTIVES

We aimed to identify markers from different pathways which represent early metabolic changes and test their predictive performance for T2D, as compared to the performance of traditional risk factors (TRF).

METHODS

We analyzed 2776 participants from the Erasmus Rucphen Family study from which 1571 disease free individuals were followed up to 14-years. The targeted metabolomics measurements at baseline were performed by three different platforms using either nuclear magnetic resonance spectroscopy or mass spectrometry. We selected 24 T2D markers by using Least Absolute Shrinkage and Selection operator (LASSO) regression and tested their association to incidence of disease during follow-up.

RESULTS

The 24 markers i.e. high-density, low-density and very low-density lipoprotein sub-fractions, certain triglycerides, amino acids, and small intermediate compounds predicted future T2D with an area under the curve (AUC) of 0.81. The performance of the metabolic markers compared to glucose was significantly higher among the young (age < 50 years) (0.86 vs. 0.77, p-value <0.0001), the female (0.88 vs. 0.84, p-value =0.009), and the lean (BMI < 25 kg/m²) (0.85 vs. 0.80, p-value =0.003). The full model with fasting glucose, TRFs, and metabolic markers yielded the best prediction model (AUC = 0.89).

CONCLUSIONS

Our novel prediction model increases the long-term prediction performance in combination with classical measurements, brings a higher resolution over the complexity of the lipoprotein component, increasing the specificity for individuals in the low risk group.

Relationship of glycemic control markers - 1,5 anhydroglucitol, fructosamine, and glycated hemoglobin among Asian Indians with different degrees of glucose intolerance

OBJECTIVE

1,5 anhydroglucitol (1,5 AG) is emerging as a marker of short-term glycemic control. We measured levels of 1,5 AG, fructosamine (FA), and glycated hemoglobin (HbA1c) in Asian Indians with different degrees of glucose intolerance.

MATERIALS AND METHODS

We recruited 210 individuals with normal glucose tolerance (NGT; n = 60), impaired glucose tolerance (IGT; n = 50), and Type 2 diabetes mellitus (T2DM; n = 100) from a large tertiary diabetes center in Chennai in Southern India. Anthropometric measurements were obtained using standardized techniques. Serum 1,5 AG (enzymatic colorimetric assay), FA (NBT/kinetic), and HbA1c (high-performance liquid chromatography) estimations were performed.

RESULTS

1,5 AG levels were significantly lower in the T2DM followed by IGT compared with the NGT group (7.9 vs. 18.8 vs. 21.8 µg/ml, P < 0.05). FA and HbA1c were higher in T2DM and IGT compared with NGT individuals (313 vs. 237 vs. 200 µmol/L, P < 0.001) (8.3 vs. 5.8 vs. 5.3%, P < 0.001).1,5 AG showed a significant negative correlation with FA (r = -0.618, P < 0.001) and HbA1c (r = -0.700, P < 0.001). 1,5 AG decreased with increasing quartiles of postprandial glucose (P for trend <0.001). However, even among individuals with HbA1c ≤7%, 27% individuals had decreased 1,5 AG plasma level (<10 µg/ml).

CONCLUSION

Circulatory levels of 1,5 AG correlate negatively with FA and HbA1c, and may provide an additional marker to assess glycemic control in patients with Type 2 diabetes.

Do glycemic marker levels vary by race? Differing results from a cross-sectional analysis of individuals with and without diagnosed diabetes

OBJECTIVE

It is well known that A1c varies by race. However, racial differences in other biomarkers of hyperglycemia are less well characterized. The objective of this study was to determine whether average levels of glycemic markers differ by race in adults with and without diagnosed diabetes, before and after accounting for postchallenge glucose.

RESEARCH DESIGN AND METHODS

This cross-sectional study included 2692 middle-aged men and women (5.5% with diagnosed diabetes; 44% African-American; and 56% white) from the Coronary Artery Risk Development in Young Adults Study (2005-2006) who had fasting glucose, 2-hour postchallenge glucose, A1c, glycated albumin, fructosamine, and 1,5-anhydroglucitol (1,5-AG) measured. Multiple linear regression was used to evaluate racial differences in mean levels of each glycemic marker stratified by the diabetes status and adjusted for sociodemographics, cardiovascular factors, and postchallenge glucose.

RESULTS

Among those with diagnosed diabetes, racial differences were not observed for any of the glycemic markers. In contrast, among those without diagnosed diabetes, African-Americans had higher mean levels than whites of A1c (β=0.19% points; 95% CI 0.14 to 0.24), glycated albumin (β=0.82% points; 95% CI 0.68 to 0.97), fructosamine (β=8.68 μmol/L; 95% CI 6.68 to 10.68), and 2-hour glucose (β=3.50 mg/dL; 95% CI 0.10 to 6.90) after multivariable adjustment, whereas there were no statistically significant racial difference in 1,5-AG. The racial differences observed for A1c, glycated albumin, and fructosamine persisted after further adjustment for fasting and 2-hour glucose and were of similar magnitude (SD units).

CONCLUSIONS

Racial differences in glycemic marker levels were evident among middle-aged adults without diagnosed diabetes even after adjustment for postchallenge glucose. Whether these racial differences in biomarkers of hyperglycemia affect the risk of complications warrants additional study.

Measurement of 1,5-anhydroglucitol in blood and saliva: from non-targeted metabolomics to biochemical assay

Background

Diabetes testing using saliva, rather than blood and urine, could facilitate diabetes screening in public spaces. We previously identified 1,5-anhydro-d-glucitol (1,5-AG) in saliva as a diabetes biomarker. The Glycomark™ assay kit is FDA approved for 1,5-AG measurement in blood. Here we evaluated its applicability for 1,5-AG quantification in saliva.

Methods

Using pooled saliva samples, we validated Glycomark™ assay use with a RX Daytona⁺ clinical chemistry analyser. We then used this set-up to analyse 82 paired blood and saliva samples from a diabetes case–control study, for which broad mass spectrometry-based characterization of the blood and saliva metabolome was also available. Osmolality was measured to account for potential variability in saliva samples.

Results

The technical variability of the read-outs for the pooled saliva samples (CV = 2.05 %) was comparable to that obtained with manufacturer-provided blood surrogate quality controls (CV = 1.38–1.8 %). We found a high correlation between Glycomark assay and mass spectrometry measurements of serum 1,5-AG (r² = 0.902), showing reproducibility of the non-targeted metabolomics results. The significant correlation between the osmolality measurements performed at two independent platforms with the time interval of 2 years (r² = 0.887), also indicates the sample integrity. The assay read-out for saliva was not correlated with the mass spectrometry-based 1,5-AG saliva measurements. Comparison with the full saliva metabolome revealed a high correlation of the saliva assay read-outs with galactose.

Conclusions

Glycomark™ assay read-outs for saliva were stable and replicable. However, the signal was dominated by galactose, which is biochemically similar to 1,5-AG and absent in blood. Adapting the 1,5-AG kit for saliva analysis will require enzymatic depletion of galactose. This should be feasible, since the assay already includes a similar step for glucose depletion from blood samples.

Metabolomics in Prediabetes and Diabetes: A Systematic Review and Meta-analysis

OBJECTIVE

To conduct a systematic review of cross-sectional and prospective human studies evaluating metabolite markers identified using high-throughput metabolomics techniques on prediabetes and type 2 diabetes.

RESEARCH DESIGN AND METHODS

We searched MEDLINE and EMBASE databases through August 2015. We conducted a qualitative review of cross-sectional and prospective studies. Additionally, meta-analyses of metabolite markers, with data estimates from at least three prospective studies, and type 2 diabetes risk were conducted, and multivariable-adjusted relative risks of type 2 diabetes were calculated per study-specific SD difference in a given metabolite.

RESULTS

We identified 27 cross-sectional and 19 prospective publications reporting associations of metabolites and prediabetes and/or type 2 diabetes. Carbohydrate (glucose and fructose), lipid (phospholipids, sphingomyelins, and triglycerides), and amino acid (branched-chain amino acids, aromatic amino acids, glycine, and glutamine) metabolites were higher in individuals with type 2 diabetes compared with control subjects. Prospective studies provided evidence that blood concentrations of several metabolites, including hexoses, branched-chain amino acids, aromatic amino acids, phospholipids, and triglycerides, were associated with the incidence of prediabetes and type 2 diabetes. We meta-analyzed results from eight prospective studies that reported risk estimates for metabolites and type 2 diabetes, including 8,000 individuals of whom 1,940 had type 2 diabetes. We found 36% higher risk of type 2 diabetes per study-specific SD difference for isoleucine (pooled relative risk 1.36 [1.24-1.48]; I(2) = 9.5%), 36% for leucine (1.36 [1.17-1.58]; I(2) = 37.4%), 35% for valine (1.35 [1.19-1.53]; I(2) = 45.8%), 36% for tyrosine (1.36 [1.19-1.55]; I(2) = 51.6%), and 26% for phenylalanine (1.26 [1.10-1.44]; I(2) = 56%). Glycine and glutamine were inversely associated with type 2 diabetes risk (0.89 [0.81-0.96] and 0.85 [0.82-0.89], respectively; both I(2) = 0.0%).

CONCLUSIONS

In studies using high-throughput metabolomics, several blood amino acids appear to be consistently associated with the risk of developing type 2 diabetes.

Metabolomic biomarkers for personalised glucose lowering drugs treatment in type 2 diabetes

We aimed to identify metabolites to predict patients' response to glucose lowering treatment during the first 5 years after detection of type 2 diabetes. Metabolites were measured by GC-MS in baseline samples from 346 screen-detected type 2 diabetes patients in the ADDITION-NL study. The response to treatment with metformin and/or sulphonylurea (SU) was analysed to identify metabolites predictive of 5 year HbA1c change by multiple regression analysis. Baseline glucose and 1,5 anhydro-glucitol were associated with HbA_1c decrease in all medication groups. In patients on SU no other metabolite was associated with HbA1c decrease. A larger set of metabolites was associated with HbA1c change in the metformin and the combination therapy (metformin + SU) groups. These metabolites included metabolites related to liver metabolism, such as 2-hydroxybutanoic acid, 3-hydroxybutanoic acid, 2-hydroxypiperidine and 4-oxoproline). Metabolites involved in oxidative stress and insulin resistance were higher when the HbA1c decrease was larger in the metformin/sulphonylurea group. The associations between baseline metabolites and responsiveness to medication are in line with its mode of action. If these results could be replicated in other populations, the most promising predictive candidates might be tested to assess whether they could enhance personalised treatment.

Association of 1,5-Anhydroglucitol With Cardiovascular Disease and Mortality

In diabetes, low concentrations of the biomarker 1,5-anhydroglucitol (1,5-AG) reflect hyperglycemic excursions over the prior 1-2 weeks. To the extent that hyperglycemic excursions are important in atherogenesis, 1,5-AG may provide independent information regarding cardiovascular risk. Nonetheless, few studies have evaluated associations of 1,5-AG with long-term cardiovascular outcomes in a population-based setting. We measured 1,5-AG in 11,106 participants in the Atherosclerosis Risk in Communities (ARIC) study without cardiovascular disease at baseline (1990-1992) and examined prospective associations with coronary heart disease (n = 1,159 events), ischemic stroke (n = 637), heart failure (n = 1,553), and death (n = 3,120) over 20 years of follow-up. Cox proportional hazards models were adjusted for demographic and cardiovascular risk factors. Compared with persons with 1,5-AG ≥6 μg/mL and no history of diabetes, persons with diabetes and 1,5-AG <6.0 μg/mL had an increased risk of coronary heart disease (HR 3.85, 95% CI 3.11-4.78), stroke (HR 3.48, 95% CI 2.66-4.55), heart failure (HR 3.50, 95% CI 2.93-4.17), and death (HR 2.44, 95% CI 2.11-2.83). There was a threshold effect, with little evidence for associations at "nondiabetic" concentrations of 1,5-AG (e.g., >10 μg/mL). Associations remained but were attenuated with additional adjustment for fasting glucose or HbA1c. These data add to the growing evidence for the prognostic value of 1,5-AG for long-term complications in the setting of diabetes.

Value of serum 1,5-anhydroglucitol measurements in childhood obesity in the continuum of diabetes

PURPOSE

The prevalence of type 2 diabetes mellitus (T2DM) and obesity are currently increasing. Accordingly, the concept of "preventing diabetes" in high-risk groups has become more important in diabetic care, but the use of glycated hemoglobin (HbA1c) as a measure has limitations in this field. The aim of this study was to investigate the utility of 1,5-anhydroglucitol (1,5-AG) in assessing prediabetes status in obese children.

METHODS

The medical records of 74 subjects aged 6-19 years (of which 27 were overweight/obese and 47 had diabetes) who had 1,5-AG data were reviewed retrospectively. We compared 1,5-AG with HbA1c using the Pearson correlation test to assess the clinical utility of 1,5-AG.

RESULTS

1,5-AG levels were higher (31.1±10.1 µg/mL vs. 7.4±7.3 µg/mL) and HbA1c levels were lower (5.5%±0.3% vs. 8.9%±2.7%) in the overweight/obese group than in the diabetics group. The range of 1,5-AG levels in obese children was wide (16.8-59.3 µg/mL), and did not have significance with HbA1c. A negative correlation between 1,5-AG and HbA1c was significant in the entire subject (r=-0.822, P<0.001), and also in the HbA1c range of 5.5% to 8% (r=-0.736, P<0.001).

CONCLUSION

1,5-AG is a valuable index in the HbA1c range of 5.5%-8% and it might be considered an early glycemic control index in insulin-resistant obese children with an HbA1c level above 5.5%. Moreover, the 1,5-AG level assessment should be presented as a supplementary tool for better compliance, as well as being an improvement in diabetes management for the short-term glucose control in relatively well-controlled diabetes patients with an HbA1c level below 8%.

Model analysis of effect of canagliflozin (Invokana), a sodium-glucose cotransporter 2 inhibitor, to alter plasma 1,5-anhydroglucitol

BACKGROUND

Renal reabsorption of 1,5-anhydroglucitol (AG) is competitively inhibited by elevated glucose and leads to depleted plasma AG in diabetes. Plasma AG recovery in diabetes normally correlates with improved glycemic control. However, use of sodium-glucose co-transporter 2 (SGLT2) inhibitors (e.g., canagliflozin) to treat diabetes by inhibition of renal glucose reabsorption can negate this correlation, via an indirect effect (increase of renal filtrate glucose concentration) to inhibit AG reabsorption by sodium-glucose co-transporter 4 (SGLT4). Conversely, then, AG measurement might be useful as an independent marker for SGLT2 inhibitor activity.

METHODS

Using an AG mass balance model, we analyzed literature data on plasma AG before and after initiation of canagliflozin therapy (CT) to quantitatively characterize the effect of CT on AG reabsorption.

RESULTS

According to model calculations, modest decreases (<5%) in fractional reabsorption of AG account for the drastic decrease in [AG] observed during CT. Decreases are predicted to be rapid (t1/2<3days) after CT initiation.

CONCLUSION

CT negates the usual premise of AG measurement (that [AG] should increase with improved glycemic control). However, according to model calculations, a substantial and likely rapid effect of CT on [AG] means that AG measurement might provide an early marker for CT activity.

Effect of postprandial hyperglycaemia on coronary flow reserve in patients with impaired glucose tolerance and type 2 diabetes mellitus

BACKGROUND

This study investigated whether postprandial hyperglycaemia has an adverse effect on coronary microvascular function and left ventricular diastolic function.

METHODS

In all, 28 patients with type 2 diabetes mellitus with no significant stenosis in left anterior descending artery were enrolled. In all subjects, plasma 1,5-anhydroglucitol was measured, and coronary flow reserve in the left anterior descending artery was evaluated using a Doppler wire. Membrane type-1 matrix metalloproteinase expression on circulating peripheral blood mononuclear cells was measured by flow cytometry. Correlation analyses were performed for coronary flow reserve and 1,5-anhydroglucitol, other coronary risk factors, membrane type-1 matrix metalloproteinase and E/e'.

RESULTS

Strong correlations were found only between 1,5-anhydroglucitol and coronary flow reserve and membrane type-1 matrix metalloproteinase. On multiple regression analysis, 1,5-anhydroglucitol remained an independent predictor of coronary flow reserve (β = 0.38, p = 0.048).

CONCLUSION

Postprandial hyperglycaemia appears to have an adverse effect on coronary microvascular function, suggesting that improvement of postprandial hyperglycaemia may contribute to the improvement of coronary microvascular dysfunction.

Epidemiology of Dysglycemia in Pregnant Oklahoma American Indian Women

CONTEXT

Minority communities are disproportionately affected by diabetes, and minority women are at an increased risk for glucose intolerance (dysglycemia) during pregnancy.

OBJECTIVES

In pregnant American Indian women, the objectives of the study were to use current criteria to estimate the prevalence of first-trimester (Tr1) dysglycemia and second-trimester (Tr2) incidence of gestational diabetes mellitus (GDM) and to explore new candidate measures and identify associated clinical factors.

DESIGN

This was a prospective cohort study. In Tr1 we performed a 75-g, 2-hour oral glucose tolerance test (OGTT) and glycated hemoglobin (HbA1c) to determine the following: fasting insulin; homeostasis model assessment of insulin resistance; serum 1,5-anhydroglucitol; noninvasive skin autofluorescence (SCOUT). We defined dysglycemia by American Diabetes Association and Endocrine Society criteria and as HbA1c of 5.7% or greater. In Tr2 in an available subset, we performed a repeat OGTT and SCOUT.

PARTICIPANTS

Pregnant American Indian women (n = 244 at Tr1; n = 114 at Tr2) participated in the study.

OUTCOMES

The prevalence of dysglycemia at Tr1 and incidence of GDM at Tr2 were measured.

RESULTS

At Tr1, one woman had overt diabetes; 36 (15%) had impaired glucose tolerance (American Diabetes Association criteria and/or abnormal HbA1c) and 59 (24%) had GDM-Tr1 (Endocrine Society criteria). Overall, 74 (30%) had some form of dysglycemia. Associated factors were body mass index, hypertension, waist/hip circumferences, SCOUT score, fasting insulin, and homeostasis model assessment of insulin resistance. At Tr2, 114 of the Tr1 cohort underwent a repeat OGTT and SCOUT, and 26 (23%) had GDM. GDM-Tr2 was associated with increased SCOUT scores (P = .029) and Tr1 body mass index, waist/hip circumferences, diastolic blood pressure, fasting insulin, and triglyceride levels. Overall, dysglycemia at Tr1 and/or Tr2 affected 38% of the women.

CONCLUSIONS

Dysglycemia at some point during pregnancy was common among American Indian women. It was associated with features of insulin resistance and may confer long-term health risks for mother and child.

A systems view of type 2 diabetes-associated metabolic perturbations in saliva, blood and urine at different timescales of glycaemic control

AIMS/HYPOTHESIS

Metabolomics has opened new avenues for studying metabolic alterations in type 2 diabetes. While many urine and blood metabolites have been associated individually with diabetes, a complete systems view analysis of metabolic dysregulations across multiple biofluids and over varying timescales of glycaemic control is still lacking.

METHODS

Here we report a broad metabolomics study in a clinical setting, covering 2,178 metabolite measures in saliva, blood plasma and urine from 188 individuals with diabetes and 181 controls of Arab and Asian descent. Using multivariate linear regression we identified metabolites associated with diabetes and markers of acute, short-term and long-term glycaemic control.

RESULTS

Ninety-four metabolite associations with diabetes were identified at a Bonferroni level of significance (p < 2.3 × 10(-5)), 16 of which have never been reported. Sixty-five of these diabetes-associated metabolites were associated with at least one marker of glycaemic control in the diabetes group. Using Gaussian graphical modelling, we constructed a metabolic network that links diabetes-associated metabolites from three biofluids across three different timescales of glycaemic control.

CONCLUSIONS/INTERPRETATION

Our study reveals a complex network of biochemical dysregulation involving metabolites from different pathways of diabetes pathology, and provides a reference framework for future diabetes studies with metabolic endpoints.

Alternative biomarkers for assessing glycemic control in diabetes: fructosamine, glycated albumin, and 1,5-anhydroglucitol

The growing attention to alternative glycemic biomarkers including fructosamine, glycated albumin (GA), 1,5-anhydroglucitol (1,5-AG), is attributable to the limitations of the glycated hemoglobin (HbA1c) assay. It is important to recognize the conditions in which HbA1c levels may be difficult to interpret. Serum fructosamine and GA have been proposed useful tools for monitoring of short-term glycemic control. These biomarkers not only reflect well glycemic control in hematologic disorder, but also represent postprandial glucose fluctuation. Serum 1,5-AG may be useful for estimating within-day glucose variation. Use of these nontraditional tests can be more helpful in the management of diabetes as complement traditional measures. Further larger cohort studies are warranted to determine whether nontraditional biomarkers have potential utility for early diagnosis, management of diabetes, and prevention of diabetic complications.

1,5-Anhydroglucitol: a new predictor of neonatal birth weight in diabetic pregnancies

OBJECTIVE

To determine whether 1,5-anhydroglucitol is predictive of neonatal birth weight.

STUDY DESIGN

A retrospective cohort study including 85 pregnancies complicated by diabetes (Type 1=37, Type 2=24, gestational=24). Women had simultaneous hemoglobin A1c and 1,5-anhydroglucitol measurements every 4-8 weeks throughout pregnancy until delivery. Neonatal birth weight was evaluated by standardized z-scores. Linear regression analysis was performed to determine an association of 1,5-anhydroglucitol with neonatal birth weight z-score.

RESULTS

Type 1 diabetic patients had the lowest mean 1,5-anhydroglucitol of 3.5mcg/mL (SD=1.6mcg/mL) and highest mean hemoglobin A1c of 6.5% (SD=0.74%) compared to gestational diabetic patients who had the highest mean 1,5-anhydroglucitol of 6.7mcg/mL (SD=3.8mcg/mL) and lowest mean hemoglobin A1c of 6.0% (SD=0.94%). Mean 1,5-anhydroglucitol values were significantly different between diabetes types (p<0.01). Mean neonatal birth weight was above population averages for all diabetes classifications, although mean birth weight z-scores did not differ significantly between diabetic types (p=0.38). Multivariate linear regression showed a negative association between log-transformed 1,5-anhydroglucitol and birth weight (coefficient -0.82, 95% CI -1.19, -0.46).

CONCLUSION

In pregnancies complicated by diabetes, low 1,5-anhydroglucitol was associated with increased neonatal birth weight. 1,5-Anhydroglucitol may be useful in the assessment of glycemic control in pregnancy in addition to A1c.

Reactivity of sorbose dehydrogenase from Sinorhizobium sp. 97507 for 1,5-anhydro-D-glucitol

Purified recombinant sorbose dehydrogenase from Sinorhizobium sp. 97507 exhibited high reactivity for 1,5-anhydro-D-glucitol (1,5-AG) and L-sorbose, but little activity for the other sugars or sugar alcohols tested. Kinetic analysis revealed that its catalytic efficiency (k(cat)/Km) for L-sorbose and 1,5-AG is 1.8 × 10(2) and 1.5 × 10(2) s(-1)·M(-1), respectively.

Untargeted metabolic profiling identifies altered serum metabolites of type 2 diabetes mellitus in a prospective, nested case control study

BACKGROUND

Application of metabolite profiling could expand the etiological knowledge of type 2 diabetes mellitus (T2D). However, few prospective studies apply broad untargeted metabolite profiling to reveal the comprehensive metabolic alterations preceding the onset of T2D.

METHODS

We applied untargeted metabolite profiling in serum samples obtained from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort comprising 300 individuals who developed T2D after a median follow-up time of 6 years and 300 matched controls. For that purpose, we used ultraperformance LC-MS with a protocol specifically designed for large-scale metabolomics studies with regard to robustness and repeatability. After multivariate classification to select metabolites with the strongest contribution to disease classification, we applied multivariable-adjusted conditional logistic regression to assess the association of these metabolites with T2D.

RESULTS

Among several alterations in lipid metabolism, there was an inverse association with T2D for metabolites chemically annotated as lysophosphatidylcholine(dm16:0) and phosphatidylcholine(O-20:0/O-20:0). Hexose sugars were positively associated with T2D, whereas higher concentrations of a sugar alcohol and a deoxyhexose sugar reduced the odds of diabetes by approximately 60% and 70%, respectively. Furthermore, there was suggestive evidence for a positive association of the circulating purine nucleotide isopentenyladenosine-5'-monophosphate with incident T2D.

CONCLUSIONS

This study constitutes one of the largest metabolite profiling approaches of T2D biomarkers in a prospective study population. The findings might help generate new hypotheses about diabetes etiology and develop further targeted studies of a smaller number of potentially important metabolites.

Human metabolic correlates of body mass index

BACKGROUND

A high body mass index (BMI) is a major risk factor for several chronic diseases, but the biology underlying these associations is not well-understood. Dyslipidemia, inflammation, and elevated levels of growth factors and sex steroid hormones explain some of the increased disease risk, but other metabolic factors not yet identified may also play a role.

DESIGN

In order to discover novel metabolic biomarkers of BMI, we used non-targeted metabolomics to assay 317 metabolites in blood samples from 947 participants and examined the cross-sectional associations between metabolite levels and BMI. Participants were from three studies in the United States and China. Height, weight, and potential confounders were ascertained by questionnaire (US studies) or direct measurement (Chinese study). Metabolite levels were measured using liquid-phase chromatography and gas chromatography coupled with mass spectrometry. We evaluated study-specific associations using linear regression, adjusted for age, gender, and smoking, and we estimated combined associations using random effects meta-analysis.

RESULTS

The meta-analysis revealed 37 metabolites significantly associated with BMI, including 19 lipids, 12 amino acids, and 6 others, at the Bonferroni significance threshold (p<0.00016). Eighteen of these associations had not been previously reported, including histidine, an amino acid neurotransmitter, and butyrylcarnitine, a lipid marker of whole-body fatty acid oxidation. Heterogeneity by study was minimal (all P_{heterogeneity} >0.05). In total, 110 metabolites were associated with BMI at the p<0.05 level.

CONCLUSION

These findings establish a baseline for the BMI metabolome, and suggest new targets for researchers attempting to clarify mechanistic links between high BMIs and disease risk.

1,5-Anhydroglucitol in saliva is a noninvasive marker of short-term glycemic control

CONTEXT

In most ethnicities at least a quarter of all cases with diabetes is assumed to be undiagnosed. Screening for diabetes using saliva has been suggested as an effective approach to identify affected individuals.

OBJECTIVE

The objective of the study was to identify a noninvasive metabolic marker of type 2 diabetes in saliva.

DESIGN AND SETTING

In a case-control study of type 2 diabetes, we used a clinical metabolomics discovery study to screen for diabetes-relevant metabolic readouts in saliva, using blood and urine as a reference. With a combination of three metabolomics platforms based on nontargeted mass spectrometry, we examined 2178 metabolites in saliva, blood plasma, and urine samples from 188 subjects with type 2 diabetes and 181 controls of Arab and Asian ethnicities.

RESULTS

We found a strong association of type 2 diabetes with 1,5-anhydroglucitol (1,5-AG) in saliva (P = 3.6 × 10(-13)). Levels of 1,5-AG in saliva highly correlated with 1,5-AG levels in blood and inversely correlated with blood glucose and glycosylated hemoglobin levels. These findings were robust across three different non-Caucasian ethnicities (Arabs, South Asians, and Filipinos), irrespective of body mass index, age, and gender.

CONCLUSIONS

Clinical studies have already established 1,5-AG in blood as a reliable marker of short-term glycemic control. Our study suggests that 1,5-AG in saliva can be used in national screening programs for undiagnosed diabetes, which are of particular interest for Middle Eastern countries with young populations and exceptionally high diabetes rates.

Pitfalls in hemoglobin A1c measurement: when results may be misleading

Since the beginning of clinical use in the 1970s, hemoglobin A1c (A1c) has become the standard tool for monitoring glycemic control in patients with diabetes. The role of the A1c test was broadened in 2010, when the American Diabetes Association added A1c as a diagnostic criterion for diabetes. Because of hemoglobin A1c's integral role in diagnosis and treatment, it is important to recognize clinical scenarios and interfering factors that yield false results. The purpose of this review is to describe the A1c measurement, outline clinical scenarios or factors that may yield false results, and describe alternative laboratory biomarkers.

Postprandial glycemic control conditions in relation to urinary N-acetyl-β-D-glucosaminidase in patients with type 2 diabetes mellitus without low glomerular filtration rate

BACKGROUND

This study assessed the relationship between the serum level of 1,5-anhydroglucitol (1,5-AG), a marker of postprandial hyperglycemia, and the ratio of the urinary activity of N-acetyl-β-D-glucosaminidase (NAG) to creatinine (NAG index) in patients with type 2 diabetes mellitus.

SUBJECTS AND METHODS

This was a cross-sectional study with 153 patients who had an estimated glomerular filtration rate of ≥60 mL/min/1.73 m(2) and no proteinuria and who had never been treated with oral hypoglycemic agents or insulin. On the basis of 1,5-AG levels, the patients were divided into a High 1,5-AG group (>14.0 μg/mL) and a Low 1,5-AG group (≤14.0 μg/mL).

RESULTS

The logarithmically transformed NAG index was significantly higher in the Low 1,5-AG group than in the High 1,5-AG group when all glycated hemoglobin (HbA1c) levels were included. The logarithmically transformed NAG index was lowest in the High 1,5-AG group with an HbA1c level of ≤6.4% and was highest in the Low 1,5-AG group with an HbA1c level of ≥7.5%. Multivariate regression analysis showed that the NAG index had a higher independent association with 1,5-AG than with HbA1c or the fasting plasma glucose level. In all models, multivariate regression analyses showed that the NAG index was correlated with age.

CONCLUSIONS

These results suggest that postprandial hyperglycemia correlates with early renal tubule injury in type 2 diabetes mellitus.

Use of complementary markers in assessing glycaemic control in people with diabetic kidney disease undergoing iron or erythropoietin treatment

AIMS

HbA(1c) values are unreliable in patients with diabetes who have chronic kidney disease who receive iron and/or erythropoiesis stimulating agents. The study aimed to evaluate the utility of the complementary glycaemic markers glycated albumin, fructosamine and 1,5 anhydroglucitol in this group of patients.

METHODS

A prospective study of patients with Type 2 diabetes and chronic kidney disease stage IIIB/IV undergoing intravenous iron or erythropoiesis-stimulating agent therapy. Glycaemic control was monitored using HbA(1c), seven-point daily glucose thrice weekly, continuous glucose monitoring, glycated albumin, fructosamine and 1,5 anhydroglucitol.

RESULTS

Fifteen patients [9 men; median age 72 years (interquartile range 68-74), follow-up period (16.4 ± 3.7 weeks)] received parenteral iron; 15 patients [11 men; 70 years (interquartile range 62-75), (17.3 ± 3.3 weeks)] received erythropoiesis-stimulating agent. HbA(1c) fell following treatment with both iron [57 mmol/mol (7.4%) to 53 mmol/mol (7.0%), P < 0.001] and erythropoiesis-stimulating agent [56 mmol/mol (7.3%) to 49 mmol/mol (6.6%), P = 0.01] despite mean blood glucose remaining unchanged (iron: 9.55 to 9.71 mmol/l, P = 0.07; erythropoiesis-stimulating agent: 8.72 to 8.78 mmol/l, P = 0.89). Unlike HbA1c , the glycated albumin, fructosamine and 1,5 anhydroglucitol levels did not change following iron [glycated albumin (16.8 to 16.3%, P = 0.10); fructosamine (259.5 to 256 μmol/l, P = 0.89); 1,5 anhydroglucitol (54.2 to 50.9 μmol/l, P = 0.89)] or erythropoiesis-stimulating agent [glycated albumin (17.9 to 17.5%, P = 0.29), fructosamine (324.3 to 306.0 μmol/l, P = 0.52), 1,5 anhydroglucitol (58.2 to 46.7 μmol/l, P = 0.35)]. Despite this, HbA(1c) was consistently the marker most closely related to mean blood glucose before and after each treatment (R range 0.7-0.88).

CONCLUSIONS

These data indicate that HbA(1c) was statistically most closely related to mean blood glucose, but clinical trends in glycaemia in patients undergoing iron or erythropoiesis-stimulating agent therapy are likely best assessed by including one of these additional glycaemic markers.

Evaluation of 1,5-anhydroglucitol as a marker for glycemic variability in patients with type 2 diabetes mellitus

1,5-anhydroglucitol (1,5-AG) has been suggested as a marker for short-term glycemic control and postprandial hyperglycemia. However, the role of 1,5-AG in glycemic variability has not been established. The aim of this study was to demonstrate the usefulness of 1,5-AG as a marker for glycemic variability in patients with type 2 diabetes. Sixty patients with type 2 diabetes were enrolled, and a continuous glucose monitoring system (CGMS) was applied for 72 h. Continuous overlapping net glycemic action (CONGA), mean amplitude of glycemic excursion (MAGE), and mean of the daily differences (MODD) were calculated for the assessment of glycemic variability and compared with 1,5-AG. Urinary 8-iso prostaglandin F2α (8-isoPGF2α) was measured to assess oxidative stress. 1,5-AG was correlated with fasting blood glucose, HbA1c, postprandial area under the curve for glucose above 180 mg/dL (AUC-180), and mean post-meal maximum glucose (MPMG). However, 1,5-AG did not show significant correlation with CONGA-1, MAGE, and MODD (R = -0.053, P = 0.689; R = -0.148, P = 0.259; R = -0.123, P = 0.350). In patients with HbA1c ≤ 8.0% (n = 35), 1,5-AG was significantly correlated with HbA1c, mean glucose, postprandial AUC-180, and MPMG. However, in patients with HbA1c > 8.0% (n = 25), 1,5-AG did not show correlation with any glycemic markers. Oxidative stress measured as urine 8-isoPGF2α showed positive correlations with CONGA-1, MAGE, AUC-180, postprandial AUC-180, and MPMG only in men. However, 1,5-AG did not correlate with oxidative stress. Our data suggested a limited usefulness of 1,5-AG in estimating glycemic variability and oxidative stress. 1,5-AG was able to represent mean glucose and postprandial hyperglycemia only in well-controlled diabetic patients.

The use of 1.5-anhydroglucitol for monitoring glycemic control in islet transplant recipients

We evaluated whether 1,5-anhydroglucitol (1,5-AG) (GlycoMark(®)), a test for measuring postprandial glucose and glucose variability, could be a tool for assessing short-term glycemic control in islet cell transplant (ICT) subjects. Data of 21 subjects, with type 1 DM and allogenic islet transplantation, who had concomitant fructosamine, HbA1c, 1,5-AG (n = 85 samples), and capillary glucose self-monitoring measurements (n = 2,979) were analyzed retrospectively at different time points after ICT. A significant negative association was observed between 1,5-AG and HbA1c (p = 0.02), but not with fructosamine. When HbA1c was divided in quartiles as <5.6, 5.6-5.9, 5.9-6.2, and >6.2, a decrease of an estimated 0.70 ± 0.30 µg/ml in 1,5-AG was associated with each quartile of increase in HbA1c (p < 0.0001). There was a significant decline of 1.64 ± 0.3mg/dl in postprandial glucose values for each 1 unit increase in 1,5-AG (p < 0.0001). For those with HbA1c ≥ 6.0% when 1,5-AG was ≥8.15 µg/ml, the mean estimated glucose level was 103.71 ± 3.66 mg/dl, whereas it was 132.12 ± 3.71 mg/dl when 1,5-AG was <8.15 µg/ml. The glucose variability (Glumax - Glumin) in subjects with 1,5-AG <8.15 µg/ml was 46.23 mg/dl greater than the subjects with 1,5-AG ≥8.15 µg/ml (HbA1c ≥ 6.0%). There was no significant association between GlycoMark and glucose variability where HbA1c < 6%. 1,5-AG significantly associated with postprandial glucose levels and glucose variability in ICT recipients with near-normal HbA1c (6.0-6.5%) levels. These findings suggest that 1,5-AG can be used to differentiate those ICT subjects with higher glucose variability despite having near-normal HbA1c. However, prospective studies are needed to evaluate the association between GlycoMark levels and the parameters of graft dysfunction/failure.

1,5-Anhydroglucitol as a marker of maternal glycaemic control and predictor of neonatal birthweight in pregnancies complicated by type 1 diabetes mellitus

AIMS/HYPOTHESIS

Most pregnant women with type 1 diabetes mellitus achieve HbA1c targets; however, macrosomia remains prevalent and better pregnancy glycaemic markers are therefore needed. 1,5-Anhydroglucitol (1,5-AG) is a short-term marker of glycaemia, reflecting a period of 1 to 2 weeks. Its excretion rate depends on the renal glucose threshold and thus it is unclear whether it may be used in pregnant type 1 diabetes women. We evaluated 1,5-AG as a glycaemic marker and birthweight predictor in pregnant women with type 1 diabetes, and compared its performance with HbA1c.

METHODS

1,5-AG and HbA1c were measured in 82 pregnant women with type 1 diabetes. In addition, 58 continuous glucose monitoring system (CGMS) records were available. Macrosomia was defined as birthweight >90th centile. The data were analysed with Pearson's correlations, and linear and logistic regression models. Receiver operating characteristic (ROC) analysis was used to evaluate third trimester 1,5-AG as a predictor of macrosomia.

RESULTS

Unlike HbA1c, 1,5-AG strongly correlated with CGMS indices: the AUC above 7.8 mmol/l (r = -0.66; p < 0.001), average maximum glucose (r = -0.58; p < 0.001) and mean glucose (r = -0.54; p < 0.001). In the third trimester, 1,5-AG was the strongest predictor of macrosomia, with ROC AUC 0.81 (95% CI 0.70, 0.89). In contrast, HbA1c in the third trimester had a ROC AUC of 0.69 (95% CI 0.58, 0.81). The best discrimination was achieved when both markers were used jointly, yielding a ROC AUC of 0.84 (95% CI 0.76, 0.93).

CONCLUSIONS/INTERPRETATION

In pregnant women with type 1 diabetes, 1,5-AG is a better glycaemic marker than HbA1c, as assessed by CGMS. A decreased third trimester 1,5-AG level, either singly or with HbA1c, is a strong predictor of macrosomia.

A profile of carbohydrate metabolites in the fasting northern elephant seal

Northern elephant seals endure prolonged periods of food deprivation at multiple life-history stages and simultaneous with energetically costly activities-including reproduction and development. Most mammals decrease their energy expenditure while fasting, with simultaneous reductions in gluconeogenesis and circulating glucose concentration. Paradoxically, elephant seals maintain high rates of both energy expenditure and gluconeogenesis, and high blood glucose concentrations throughout fasting. We therefore characterized the suite of changes that occur in carbohydrate metabolites during fasting in northern elephant seals. Using a broad-based metabolomics platform we investigated fasting during two states-lactation in adult females and the post-weaning developmental period in pups. A total of 227 metabolites were detected in seal plasma; 31 associated with carbohydrate metabolism were analyzed in the present study. Several compounds showed similar responses during lactation and the post-weaning fast (e.g. glycerol and mesaconate) whereas other compounds displayed quite different abundances between groups (e.g. citrate and pyruvate). This work found that, while the changes that occur with fasting were frequently similar in lactating females and developing pups, the relative abundance of compounds often varied markedly. These differences suggest that the metabolic strategies used to endure prolonged fasts are influenced by life-history or nutrient constraints.

1,5-Anhydroglucitol in diabetes mellitus

The measure of glycated hemoglobin (HbA1c) concentration is the gold standard of glycemic control index in diabetes management and is well known as a marker for diabetes complications. However, HbA1c level neither accurately reflect glucose fluctuations, nor does it provide a clear indication of glycemic control in recent days or weeks. HbA1c concentration measurement can be confounded in patients with anemia, hemoglobinopathy, liver disease, or renal impairment. 1,5-Anhydroglucitol (1,5-AG) structurally resembles glucose. It can be influenced by diet or medication, gender and race, especially severe renal disease and various pathological conditions. Most notably, 1,5-AG level is reflective of short-term glucose status, postprandial hyperglycemia, and glycemic variability which are not captured by HbA1c assay. 1,5-AG may suggest an alternative index of subtypes of diabetes and a warning sign of diabetes complications. This review provides an overview of our current understanding of the role of 1,5-AG marker in diabetes. However, further investigations on the associations between this glycemic marker and diabetes complications are needed.

Increased 1,5-anhydroglucitol predicts glycemic remission in patients with newly diagnosed type 2 diabetes treated with short-term intensive insulin therapy

BACKGROUND

Short-term intensive insulin therapy has been shown to induce long-term glycemic remission in patients with newly diagnosed type 2 diabetes. However, predictors of remission are still uncertain. This study was conducted to evaluate whether changes of 1,5-anhydroglucitol (1,5AG) and fructosamine (FA) could be a predictor of remission.

SUBJECTS AND METHODS

Newly diagnosed drug-naive patients with type 2 diabetes (n = 64) were enrolled. After baseline assessments, continuous subcutaneous insulin infusion (CSII) was administered in all patients until euglycemia was achieved and maintained for another 2 weeks. Patients were subsequently followed monthly for 3 months. 1,5AG and FA were measured before and after therapy and at 1-month follow-up.

RESULTS

After CSII, A1C and FA decreased from baseline, whereas 1,5AG increased. 1,5AG was higher at 1-month follow-up (11.5 ± 4.1 vs. 6.7 ± 2.8 mg/L, P<0.001), whereas FA was lower (273.1 ± 56.1 vs. 316.2 ± 39.3 μmol/L, P = 0.021) in the remission group. Stepwise logistic regression analysis showed that 1,5AG at 1-month follow-up rather than FA was an independent predictor of remission after adjusting for other confounders (odds ratio 1.56, 95% confidence interval [CI] 1.15-2.12, P = 0.004). The area under the curve of the receiver operating characteristic curve analysis was 0.85 (95% CI 0.75-0.96, P<0.001). The optimal cutoff point for 1,5AG at 1-month follow-up was 8.9 mg/L (specificity, 83.3%; sensitivity, 78.6%).

CONCLUSIONS

Improvement of 1,5AG predicts maintenance of glycemic remission after intensive insulin therapy in patients with newly diagnosed type 2 diabetes.

Potential for use of 1,5-anhydroglucitol when initiating insulin therapy in people with type 2 diabetes and suboptimal control with oral antidiabetic drugs

Endpoint HbA(1c) <7.0% was achieved by 80 (73.4%) lispro mix 25 (LM25)-treated patients and 67 (60.9%) glargine-treated patients (p=0.027) with baseline 1,5 anhydroglucitol (1,5AG) below median and 75 (70.8%) LM25-treated patients and 72 (63.7%) glargine-treated patients (p=0.238) with 1,5AG≥median, suggesting, 1,5AG may offer therapeutic insight when starting insulin therapy.

Evaluation of 1,5-anhydroglucitol, hemoglobin A1c, and glucose levels in youth and young adults with type 1 diabetes and healthy controls

BACKGROUND AND OBJECTIVE

Serum 1,5-anhydroglucitol (1,5-AG) is a marker of hyperglycemic excursions in adults with diabetes and hemoglobin A1c (HbA1c) < 8%. We compared 1,5-AG levels among youth and young adults with and without type 1 diabetes (T1D) and investigated the utility of 1,5-AG in the assessment of glycemic status in pediatric T1D.

METHODS

We compared 1,5-AG, HbA1c, and plasma glucose levels in 138 patients with T1D (duration ≥1 yr) and 136 healthy controls, aged 10-30 yr. Within each group, we investigated associations between 1,5-AG and clinical characteristics, HbA1c and random plasma glucose. For patients with T1D, 1,5-AG was further analyzed according to HbA1c strata: <8, 8-9, and >9%.

RESULTS

Compared to controls, patients with T1D had higher HbA1c (8.5 ± 1.6 vs. 5.1 ± 0.4%, p < 0.0001), lower 1,5-AG (4.0 ± 2.0 vs. 24.7 ± 6.4 µg/mL, p < 0.0001), and higher glucose (11.1 ± 5.2 vs. 5.1 ± 0.9 mmol/L, p < 0.0001). Males had higher 1,5-AG than females within patients (4.5 ± 2.3 vs. 3.4 ± 1.6 µg/mL, p = 0.003) and controls (26.0 ± 6.6 vs. 23.5 ± 6.0 µg/mL, p = 0.02). 1,5-AG was not correlated with glucose in either group. 1,5-AG was significantly correlated to HbA1c in patients, but not controls. For patients with HbA1c < 8%, 1,5-AG demonstrated the widest range and was not predicted by HbA1c; 1,5-AG levels were narrowly distributed among patients with HbA1c ≥ 8%.

CONCLUSIONS

Youth and young adults with T1D demonstrate similar 1,5-AG levels which are distinct from controls. 1,5-AG assessment may provide unique information beyond that provided by HbA1c in the mid-term assessment of glycemic control in young patients with T1D and HbA1c < 8%.

The interrelationships of glycemic control measures: HbA1c, glycated albumin, fructosamine, 1,5-anhydroglucitrol, and continuous glucose monitoring

OBJECTIVES

To describe the interrelationships of glycemic control measures: hemoglobin A1c (HbA1c), glycated albumin, fructosamine, 1,5-anhydroglucitrol (1,5-AG), and continuous glucose monitoring (CGM) in children and adolescents with type 1 diabetes.

METHODS

In total, 26 subjects of age 4-17 had HbA1c measurement followed within 14 d by three laboratory measures of glycemia and the collection of CGM glucose data (N = 21).

RESULTS

Glycated albumin and fructosamine levels had a higher correlation with each other than with HbA1c. The correlation of 1,5-AG with HbA1c was lower (absolute r value = 0.25). All four measures had a similar degree of correlation with CGM-measured mean glucose (absolute r value = 0.50-0.56) and with hyperglycemic area under the curve (AUC) at 180 mg/dL (0.50-0.60).

CONCLUSION

Each of the four measures (i.e., HbA1c, glycated albumin, fructosamine, and 1,5-AG) had a similar correlation with mean glucose and hyperglycemic AUC-180. 1,5-AG did not correlate with hyperglycemic AUC-180 better than did HbA1c.

Metabolic footprint of diabetes: a multiplatform metabolomics study in an epidemiological setting

BACKGROUND

Metabolomics is the rapidly evolving field of the comprehensive measurement of ideally all endogenous metabolites in a biological fluid. However, no single analytic technique covers the entire spectrum of the human metabolome. Here we present results from a multiplatform study, in which we investigate what kind of results can presently be obtained in the field of diabetes research when combining metabolomics data collected on a complementary set of analytical platforms in the framework of an epidemiological study.

METHODOLOGY/PRINCIPAL FINDINGS

40 individuals with self-reported diabetes and 60 controls (male, over 54 years) were randomly selected from the participants of the population-based KORA (Cooperative Health Research in the Region of Augsburg) study, representing an extensively phenotyped sample of the general German population. Concentrations of over 420 unique small molecules were determined in overnight-fasting blood using three different techniques, covering nuclear magnetic resonance and tandem mass spectrometry. Known biomarkers of diabetes could be replicated by this multiple metabolomic platform approach, including sugar metabolites (1,5-anhydroglucoitol), ketone bodies (3-hydroxybutyrate), and branched chain amino acids. In some cases, diabetes-related medication can be detected (pioglitazone, salicylic acid).

CONCLUSIONS/SIGNIFICANCE

Our study depicts the promising potential of metabolomics in diabetes research by identification of a series of known and also novel, deregulated metabolites that associate with diabetes. Key observations include perturbations of metabolic pathways linked to kidney dysfunction (3-indoxyl sulfate), lipid metabolism (glycerophospholipids, free fatty acids), and interaction with the gut microflora (bile acids). Our study suggests that metabolic markers hold the potential to detect diabetes-related complications already under sub-clinical conditions in the general population.

Once weekly exenatide compared with insulin glargine titrated to target in patients with type 2 diabetes (DURATION-3): an open-label randomised trial

BACKGROUND

Diabetes treatments are needed that are convenient, provide effective glycaemic control, and do not cause weight gain. We aimed to test the hypothesis that improvement in haemoglobin A(1c) (HbA(1c)) achieved with once weekly exenatide was superior to that achieved with insulin glargine titrated to glucose targets.

METHODS

In this 26-week, open-label, randomised, parallel study, we compared exenatide with insulin glargine in adults with type 2 diabetes who had suboptimum glycaemic control despite use of maximum tolerated doses of blood-glucose-lowering drugs for 3 months or longer. Patients were randomly assigned to add exenatide (2 mg, once-a-week injection) or insulin glargine (once-daily injection, starting dose 10 IU, target glucose range 4.0-5.5 mmol/L) to their blood-glucose-lowering regimens. Randomisation was with a one-to-one allocation and block size four, stratified according to country and concomitant treatment (70% metformin only; 30% metformin plus sulphonylurea). Participants and clinical investigators were not masked to assignment, but investigators analysing data were. The primary endpoint was change in HbA(1c) from baseline, and analysis of this outcome was by modified intention to treat for all patients who received at least one dose of study drug. This trial is registered at ClinicalTrials.gov, number NCT00641056.

FINDINGS

456 patients were randomly allocated to treatment and were included in the modified intention-to-treat analysis (233 exenatide, 223 insulin glargine). Participants who received at least one dose of study drug and for whom baseline and at least one postbaseline measurement of HbA(1c) were available were included in the primary efficacy analysis. Change in HbA(1c) at 26 weeks was greater in patients taking exenatide (n=228; -1.5%, SE 0.05) than in those taking insulin glargine (n=220; -1.3%, 0.06; treatment difference -0.16%, 0.07, 95% CI -0.29 to -0.03). 12 (5%) of 233 patients allocated to exenatide and two (1%) of 223 taking insulin glargine discontinued participation because of adverse events (p=0.012). A planned extension period (up to 2.5 years' duration) is in progress.

INTERPRETATION

Once weekly exenatide is an important therapeutic option for patients for whom risk of hypoglycaemia, weight loss, and convenience are particular concerns.

FUNDING

Amylin Pharmaceuticals; Eli Lilly and Company.

Lack of correlation between 1,5-anhydroglucitol assay and oral glucose tolerance test in patients with cystic fibrosis

OBJECTIVE

To determine whether the 1,5-anhydroglucitol (1,5-AG) assay, which reflects serum glucose levels during the preceding 2 weeks, could be used as an alternative to the current standard screening test for cystic fibrosis-related diabetes (CFRD)-the oral glucose tolerance test (OGTT).

METHODS

Serum 1,5-AG, hemoglobin A1c (A1C), fructosamine, and glucose at various time intervals during the OGTT were measured in 10 patients, 19 to 36 years old, with cystic fibrosis. Correlation coefficients were calculated to compare 1,5-AG with A1C, fructosamine, and serum glucose levels during the OGTT, and the mean 1,5-AG, A1C, and fructosamine for normal glucose tolerance, impaired glucose tolerance (IGT), and CFRD were compared statistically.

RESULTS

On the basis of the 120-minute OGTT, 1 of the 10 study subjects had CFRD and 4 had IGT. The mean 1,5-AG for patients with normal glucose tolerance was not significantly different from that for patients with IGT (P = .063). The 1,5-AG value was not significantly correlated with serum glucose during the OGTT, A1C, or fructosamine.

CONCLUSION

In this pilot study, we found no significant correlation between 1,5-AG and glucose values during the OGTT or between 1,5-AG and other glycemic markers. Hence, the utility of the 1,5-AG assay for screening for CFRD in the population of patients with cystic fibrosis may be limited.

Evaluation of serum 1,5 anhydroglucitol levels as a clinical test to differentiate subtypes of diabetes

OBJECTIVE

Assignment of the correct molecular diagnosis in diabetes is necessary for informed decisions regarding treatment and prognosis. Better clinical markers would facilitate discrimination and prioritization for genetic testing between diabetes subtypes. Serum 1,5 anhydroglucitol (1,5AG) levels were reported to differentiate maturity-onset diabetes of the young due to HNF1A mutations (HNF1A-MODY) from type 2 diabetes, but this requires further validation. We evaluated serum 1,5AG in a range of diabetes subtypes as an adjunct for defining diabetes etiology.

RESEARCH DESIGN AND METHODS

1,5AG was measured in U.K. subjects with: HNF1A-MODY (n = 23), MODY due to glucokinase mutations (GCK-MODY, n = 23), type 1 diabetes (n = 29), latent autoimmune diabetes in adults (LADA, n = 42), and type 2 diabetes (n = 206). Receiver operating characteristic curve analysis was performed to assess discriminative accuracy of 1,5AG for diabetes etiology.

RESULTS

Mean (SD range) 1,5AG levels were: GCK-MODY 13.06 microg/ml (5.74-29.74), HNF1A-MODY 4.23 microg/ml (2.12-8.44), type 1 diabetes 3.09 microg/ml (1.45-6.57), LADA 3.46 microg/ml (1.42-8.45), and type 2 diabetes 5.43 (2.12-13.23). Levels in GCK-MODY were higher than in other groups (P < 10(-4) vs. each group). HNF1A-MODY subjects showed no difference in unadjusted 1,5AG levels from type 2 diabetes, type 1 diabetes, and LADA. Adjusting for A1C revealed a difference between HNF1A-MODY and type 2 diabetes (P = 0.001). The discriminative accuracy of unadjusted 1,5AG levels was 0.79 for GCK-MODY versus type 2 diabetes and 0.86 for GCK-MODY versus HNF1A-MODY but was only 0.60 for HNF1A-MODY versus type 2 diabetes.

CONCLUSIONS

In our dataset, serum 1,5AG performed well in discriminating GCK-MODY from other diabetes subtypes, particularly HNF1A-MODY. Measurement of 1,5AG levels could inform decisions regarding MODY diagnostic testing.

Screening for type 2 diabetes in obese youth

OBJECTIVE

To assess available blood tests as potential screening tools for impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM).

METHODS

We studied 468 obese (BMI mean: 34.4 kg/m(2)) children, including a subgroup with serum fasting insulin levels of >15 microIU/mL. Fasting laboratory tests included measurements of serum glucose and insulin, hemoglobin A1c (HbA1c), and 1,5-anhydroglucitol (insulin-resistant subgroup only) levels. An oral glucose-tolerance test was performed on each patient, and 2-hour postload serum glucose and insulin levels were obtained. Fasting blood glucose (BG), Homeostasis Model of Assessment for Insulin Resistance (HOMA-IR), HbA1c, and 1,5-anhydroglucitol values were used as predictors for exceeding various 2-hour BG cut-offs. Receiver operator characteristic curves were fitted to determine area-under-the-curve values as measures of screening efficacy.

RESULTS

In the insulin-resistant subgroup, 3 (2%) patients had T2DM and 23 (12%) had IGT. Optimal sensitivity and specificity to detect T2DM were, respectively, 99% and 96% at HbA1c >or= 6.0%, and 96% and 88% at 1,5-anhydroglucitol < 17.0 microg/mL, with lower values for fasting BG and the HOMA-IR. In the entire study group, 9 (2%) patients had T2DM and 44 (9%) had IGT. Optimal sensitivity and specificity to detect T2DM were, respectively, 86% and 85% at HbA1c levels of 5.7%, 88%, and 93% at a fasting BG level of 104 mg/dL, and 62% and 70% at an HOMA-IR of 7.9.

CONCLUSIONS

HbA1c, 1,5-anhydroglucitol, and fasting BG levels are good predictors of T2DM in obese children, whereas HOMA-IR values are not. HbA1c and 1,5-anhydroglucitol are excellent predictors of T2DM in insulin-resistant obese children.

The clinical use of hemoglobin A1c

Hemoglobin A1c (HbA1c) has been accepted as an index of glycemic control since the mid-1970s and is the best marker for diabetic microvascular complications. Clinically, it is now used to assess glycemic control in people with diabetes. Assays are most reliable when certified by the National Hemoglobin Standardization Program but are subject to confounders and effect modifiers, particularly in the setting of hematologic abnormalities. Other measures of chronic glycemic control-fructosamine and 1,5-anhydroglucitol-are far less widely used. The relationship of HbA1c to average blood glucose was intensively studied recently, and it has been proposed that this conversion can be used to report an "estimated average glucose, eAG" in milligrams/deciliter or millimolar units rather than as per cent glycated hemoglobin. Finally, HbA1c has been proposed as a useful method of screening for and diagnosing diabetes.

1,5-Anhydroglucitol reflects postprandial hyperglycemia and a decreased insulinogenic index, even in subjects with prediabetes and well-controlled type 2 diabetes

To examine the serum 1,5-anhydroglucitol (AG) levels as a surrogate measure of postprandial hyperglycemia (PPH) and insulin secretion in a wide range of hyperglycemia, we compared the relationship between the glycemic index during a 75g oral glucose tolerance test (OGTT) and the insulinogenic index and 1,5-AG according the overall glycemic state. Fasting serum 1,5-AG levels were lower in the type 2 diabetic group (18.0+/-7.0microg/mL) than in the normal glucose tolerance (NGT, 25.4+/-4.0microg/mL), impaired fasting glucose (IFG, 24.6+/-6.2microg/mL), and impaired glucose tolerance (IGT, 22.1+/-6.2microg/mL) groups and were clearly correlated with glycemic values from the OGTT. 120-min post-challenge plasma glucose (PPG(120)) emerged as an independent predictor for 1,5-AG levels after multiple linear regression analysis (beta=-0.554, P<0.001). Additionally, 1,5-AG levels were significantly correlated with PPG(120) in each quartile of A1C, and the coefficients increased with higher A1C quartiles. Subjects with low 1,5-AG levels had both increased insulin resistance and decreased insulin secretion. Decreased 1,5-AG levels are closely correlated with PPH and decreased insulin secretion capacity across a wide range of glycemia, even in relatively well-controlled diabetes.