The influence of traditional Chinese herbal drugs on serum 1, 5-anhydroglucitol levels

Applications and pitfalls of hemoglobin A1C and alternative methods of glycemic monitoring

INTRODUCTION

Intensive glycemic control minimizes the risks of microvascular complications in diabetes. A1C is a convenient estimate of mean blood glucose, but is not the only marker available. The practical use and limitations of alternative markers and continuous glucose monitors are the focus of this review.

METHODS

PubMed and the Cochrane Library were searched for studies concerning applications or limitations of A1C, fructosamine, glycated albumin, 1,5-anhydroglucitol, skin autofluorescence, and continuous glucose monitoring. Papers reporting on strengths, limitations, or comparisons of these methods were reviewed for inclusion.

RESULTS

A1C reflects three months of glycemic control and is not an ideal marker in all patient populations. Fructosamine and glycated albumin reflect mean blood glucose over three weeks. 1,5-Anhydroglucitol can measure hyperglycemic excursions in days to weeks. Continuous glucose monitors provide immediate feedback for timely intervention to reduce glycemic excursions and can assess glycemic variability. Current barriers to continuous glucose monitor use include inexperience, cost, discomfort, and medication interference.

CONCLUSIONS

Many promising alternative glycemic markers exist. The main limitations for all alternative methods of glycemic monitoring are a lack of standardization for clinically useful cut-offs or guidelines, and a lack of long-term data on their association with complications, particularly in varied patient populations.

Indicators of glycemic control in patients with gestational diabetes mellitus and pregnant women with diabetes mellitus

Recently, it has become clear that mild abnormal glucose tolerance increases the incidence of perinatal maternal-infant complications, and so the definition and diagnostic criteria of gestational diabetes mellitus (GDM) have been changed. Therefore, in patients with GDM and pregnant women with diabetes mellitus, even stricter glycemic control than before is required to reduce the incidence of perinatal maternal-infant complications. Strict glycemic control cannot be attained without an indicator of glycemic control; this review proposes a reliable indicator. The gold standard indicator of glycemic control in patients with diabetes mellitus is hemoglobin A1c (HbA1c); however, we have demonstrated that HbA1c does not reflect glycemic control accurately during pregnancy because of iron deficiency. It has also become clear that glycated albumin, another indicator of glycemic control, is not influenced by iron deficiency and therefore might be a better indicator of glycemic control in patients with GDM and pregnant women with diabetes mellitus. However, large-population epidemiological studies are necessary in order to confirm our proposal. Here, we outline the most recent findings about the indicators of glycemic control during pregnancy including fructosamine and 1,5-anhydroglucitol.

1,5-Anhydroglucitol and glycated albumin in glycemia

The main purpose of treating diabetes is to prevent the onset and the progression of diabetic chronic complications. Since the mechanism of onset of chronic complications is still not well understood, the main strategy to achieve this purpose is to bring the plasma glucose level in diabetic patients as close as possible to that in healthy subjects and try to maintain good glycemic control over the long term. Glycated hemoglobin (HbA1c), glycated albumin (GA), fructosamine, and 1,5-anhydroglucitol (1,5 AG) are used for evaluating glycemic control. At present, HbA1c is widely used as a gold standard index for glycemic control in clinical practice. While HbA1c reflects the long-term glycemic control state (for the past 1-2 months), it does not accurately reflect glycemic control in the clinical state in which glycemic control improves or deteriorates in the short-term. It is also known that HbA1c in patients with hematological disorders such as anemia and variant hemoglobin shows an abnormal value. In addition, HbA1c mainly reflects the mean plasma glucose but does not reflect the postprandial plasma glucose. On the other hand, GA and 1,5-AG reflect intermediate- or short-term glycemic control and are not influenced by hemoglobin metabolism. While 1,5-AG is known to reflect the postprandial plasma glucose, it was shown recently that GA also reflects the postprandial plasma glucose. This chapter summarizes the measurement methods, usage methods, evidence, and problems concerning such indices for glycemic control.

Cotreatment with the α-glucosidase inhibitor miglitol and DPP-4 inhibitor sitagliptin improves glycemic control and reduces the expressions of CVD risk factors in type 2 diabetic Japanese patients

OBJECTIVE

In this study, we examined whether inhibition of postprandial hyperglycemia by combination therapy with two drugs for reducing postprandial hyperglycemia, i.e., α-glucosidase inhibitor miglitol and dipeptidyl peptidase (DPP)-4 inhibitor sitagliptin, improves glycemic control and reduces the risk of cardiovascular disease (CVD) development.

MATERIALS/METHODS

We enrolled 32 type 2 diabetic Japanese patients with hemoglobin A1c (HbA1c) levels ranging from 6.9% to 10.5%, who had been treated for at least 2 months with 50mg miglitol (t.i.d.) or 50 mg sitagliptin (q.d.). Following a monotherapy period with either miglitol (Group-M) or sitagliptin (Group-S) for 1 month, the patients were subjected to combination therapy with sitagliptin and miglitol for 3 months. Meal tolerance tests were performed at the end of the monotherapy and combination therapy.

RESULTS

Combination therapy for 3 months after monotherapy reduced HbA1c (changes: Group-M: -1.3%±0.7%, P<0.001; Group-S: -0.6%±0.5%, P<0.001) and glycoalbumin levels and increased 1,5-anhydroglucitol concentrations in the blood. In the meal tolerance tests, circulating active glucagon-like peptide-1 levels were elevated in both groups, while active glucose-dependent insulinotropic polypeptide levels were reduced by combination therapy in the group with add-on miglitol therapy. The plasma protein concentrations of interleukin (IL)-8 and adhesion molecules (sE-selectin and sVCAM-1) were reduced by switching to the combination therapy, in particular with the add-on miglitol therapy.

CONCLUSIONS

Our results suggest that combination therapy with miglitol and sitagliptin improves glycemic control and reduces the circulating protein concentrations of IL-8, sE-selectin, and sVCAM-1 in type 2 diabetic Japanese patients.

Protective effects of dietary 1,5-anhydro-D-glucitol as a blood glucose regulator in diabetes and metabolic syndrome

1,5-Anhydro-D-glucitol (1,5-AG) is fairly widespread in food products. It is also one of the major polyols in the human body, and its concentration is homeostatically regulated. We report here on the beneficial effects of 1,5-AG in preventing hyperglycemia and its role in improving metabolic syndrome. The findings revealed that it does not affect blood glucose levels itself under normal conditions but clearly has a suppressive effect on the levels of dietary sugars, such as glucose, maltose, and sucrose. A long-term administration study revealed that feeding db/db diabetic mice 3% 1,5-AG for 8 weeks significantly decreased blood glucose levels compared to untreated mice (339 ± 30 versus 438 ± 34 mg/dL; p < 0.05). Furthermore, this treatment also significantly suppressed serum cholesterol levels (110.2 ± 18.0 versus 168.4 ± 9.8 mg/dL; p < 0.01). 1,5-AG did not inhibit intestinal α-glucosidase activities but regulated liver glucose levels via affecting both the glycogenolysis and gluconeogenesis pathways. Furthermore, the oral administration of 1,5-AG significantly increased urinary glucose excretion in hyperglycemic conditions. These results clearly suggest that dietary 1,5-AG acts as a modulator of glucose levels in hyperglycemia. 1,5-AG therefore represents a new class of promising functional sweeteners, where the daily consumption of 1,5-AG with meals could inhibit the progress of hyperglycemia and metabolic syndrome.

Treatment with the α-glucosidase inhibitor miglitol from the preonset stage in Otsuka Long-Evans Tokushima Fatty rats improves glycemic control and reduces the expression of inflammatory cytokine genes in peripheral leukocytes

Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of type 2 diabetes mellitus, exhibit chronic and slowly progressive hyperglycemia with obesity. In this study, we examined whether dietary supplementation with the α-glucosidase inhibitor miglitol from the preonset stage improves glycemic control and reduces the gene expression of inflammatory cytokines in peripheral leukocytes. The OLETF rats were fed a control diet or a diet containing 800 ppm miglitol (miglitol diet) for 40 weeks from 5 weeks of age (preonset stage). We determined nonfasting blood glucose, blood 1,5-anhydroglucitol, and messenger RNA levels of inflammatory cytokines in peripheral leukocytes in these rats. Nonfasting blood glucose concentrations gradually increased in OLETF rats fed the control diet, with significant increases at weeks 28 and 40 compared with week 0. In contrast, nonfasting blood glucose levels did not increase in miglitol-treated rats during the experimental period. Miglitol-treated rats had lower nonfasting blood glucose levels and higher 1,5-anhydroglucitol levels, a marker for glucose fluctuations, at week 40 than control rats. The gene expression of inflammatory cytokines including interleukin-6, tumor necrosis factor-α, and interferon-γ in peripheral leukocytes gradually increased during the development of diabetes in control rats, but not in miglitol-treated rats. Our results suggest that dietary supplementation with miglitol from the preonset stage in OLETF rats improves glycemic control and reduces gene expression of cytokines related to inflammation in peripheral leukocytes.

Traditional used Plants against Cognitive Decline and Alzheimer Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized clinically by progressive memory deficits, impaired cognitive function, and altered and inappropriate behavior. Aging represents the most important risk factor for AD and the global trend in the phenomenon of population aging has dramatic consequences for public health, healthcare financing, and delivery systems in the word and, especially in developing countries. Mounting evidence obtained in in vitro and in vivo studies, suggests that various traditionally used plants in Asia, India, and Europe significantly affect key metabolic alterations culminating in AD-typical neurodegeneration. The present article aims to bring the reader up-to-date on the most recent studies and advances describing the direct and indirect activities of traditional used plants and its constituents possibly relieving features of AD. A variety of traditional used plants and its extracts exerted activities on AD related drug targets including AChE activity, antioxidative activity, modulation of Aβ-producing secretase activities, Aβ-degradation, heavy metal chelating, induction of neurotrophic factors, and cell death mechanisms. Although pre-clinical investigations identified promising drug candidates for AD, clinical evidences are still pending.

Habitual intake of dairy products influences serum 1,5-anhydroglucitol levels independently of plasma glucose

1,5-Anhydroglucitol (1,5-AG), a marker of glycemic control state, is reabsorbed via SGLT (sodium glucose cotransporter)-4 (SLC5A9) at renal proximal tubules. SGLT4 is responsible for reabsorption of mannose, fructose, galactose, glucose, and 1,5-AG. Thus, based on our hypothesis that serum 1,5-AG levels are influenced by diet, we investigated whether eating habits influence serum 1,5-AG levels. In total, 330 subjects (158 males and 172 females) with normal glucose tolerance participated. Relationships between serum 1,5-AG levels and eating habits (intake of meats, fish, soybean products, eggs, dairy products, fruit, vegetables, and salt) surveyed by questionnaire were investigated. Stepwise multivariate regression analysis revealed that habitual intake of dairy products was a significant negative explanatory variable for serum 1,5-AG levels. Serum 1,5-AG levels were lower in subjects with habitual intake of dairy products than in those without. On the other hand, HbA(1C), glycated albumin, fasting plasma glucose, and OGTT 2-h plasma glucose were not different between the subjects of these two groups. In conclusion, habitual intake of dairy products was associated with low serum 1,5-AG levels, independently of plasma glucose levels.

1,5-Anhydroglucitol attenuates cytokine release and protects mice with type 2 diabetes from inflammatory reactions

1,5-anhydroglucitol (1,5-AG) decreases in diabetic patients and is used as a marker of glycemic control. Type 2 diabetic patients are susceptibile to lipopolysaccharides (LPS), which stimulate macrophages to release large quantities of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6. This study examines the effects of 1,5-AG on lung inflammation induced by LPS and consequent systemic inflammation to determine whether the decrease of 1,5-AG concentration induces susceptibility to LPS. Before the challenge with LPS (1 mg/kg in vivo and 500 ng/ml in vitro), we pretreated db/db mice and RAW264.7 cells with 1,5-AG at 38.5 mg/kg and 500 microg/ml, respectively. The levels of IL-6, TNF-alpha, macrophage chemoattractant protein (MCP)-1 and IL-1beta in the serum and in the cell supernatants were measured. We also measured macrophage recruitment and the expression of inducible nitric oxide synthase (iNOS) in pulmonary tissues. We found that 1,5-AG attenuated serum cytokine release and protected db/db mice from LPS-induced pulmonary inflammation. In addition, 1,5-AG suppressed cytokine release and iNOS expression by suppressing Akt/NF-kB activity in RAW264.7 cells. These results suggest that 1,5-AG may be a mediator in, as well as marker for diabetes, and 1,5-AG intake may confer tolerance to LPS in patients with type 2 diabetes.

1,5-anhydroglucitol monitoring in diabetes: a mass balance perspective

1,5-anhydroglucitol (AG) is a nonmetabolizable glucose analogue found in plasma due to ingestion. The normal steady-state concentration can be dramatically decreased by inhibition of tubular reabsorption during periods of hyperglycemia. For this reason, monitoring of AG has been plausibly advocated for detection of periodic glucosuric hyperglycemia. In this review, we examine the influence of variation in factors affecting both steady-state and transient changes in plasma AG. Among normals, the lower and upper limits of the plasma AG reference range vary by a factor of 5. Using a simplified mass balance model (a single compartment model with 3-6x larger-than-plasma volume of distribution), reasonable inter-individual variations of ingestion rate, glomerular filtration rate and fractional post-filtration reabsorption are each able to account for the wide range of normal, steady-state AG concentrations. In monitoring of changes in AG, inter-individual variations in the threshold for glucose excretion, volume of distribution and glomerular filtration rate are all likely to significantly affect correspondence of integral changes in AG to integral glucosuria/hyperglycemia. This combination of variables, affecting both steady-state and transient changes, is significantly confounding with respect to interpretation of serial plasma AG concentrations. Resolution of information content of AG monitoring is thus largely that of crossing simple characterization of deltas [+,0,-] for changes in AG concentration against the information content of hemoglobin A1c monitoring. Despite this limitation, AG monitoring can in principle provide information about glycemic control in the short term that is not apparent through monitoring of hemoglobin A1c alone. However, whether AG monitoring can lead to improved outcomes in diabetes management remains to be established.

1,5-anhydroglucitol (GlycoMark) as a marker of short-term glycemic control and glycemic excursions

1,5-anhydroglucitol (1,5-AG) is a validated marker of short-term glycemic control. It is a metabolically inert polyol that competes with glucose for reabsorption in the kidneys. Otherwise stable levels of 1,5-AG are rapidly depleted as blood glucose levels exceed the renal threshold for glucosuria. 1,5-AG more accurately predicts rapid changes in glycemia than hemoglobin A1C (A1C) or fructosamine. It is also more tightly associated with glucose fluctuations and postprandial glucose. Thus, 1,5-AG may offer complementary information to A1C. This review will summarize the limitations of current methods of assessing glycemic control, assess the data to support 1,5-AG as a glycemic marker and highlight the scenarios by which 1,5-AG may fill the gap in assessing glycemic control.

Serum 1,5-anhydroglucitol (Glycomark) levels in children with and without type 1 diabetes mellitus

Postprandial hyperglycemia associated with diabetes is a risk factor for cardiovascular disease. Currently, glycated hemoglobin A(1c) (HgbA(1c)) and glycated protein fructosamine are not sensitive markers for acute and short-term hyperglycemia. 1,5-Anhydroglucitol (1,5-AG) (Glycomark; Tomen America, New York, NY, USA) is reported in adults with type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) as a marker for postmeal hyperglycemia. However, the reference ranges for 1,5-AG in normal children and children with T1DM are not known. We studied 1,5-AG levels in 10 control children (6 males and 4 females) and 10 children with T1DM (7 males and 3 females). The levels of 1,5-AG in the normal controls were higher than those in children with T1DM (24.60 +/- 3.99 microg/mL vs. 4.75 +/- 2.95 microg/mL; p < 0.0001). There were no gender differences noted. The 1,5-AG levels were negatively correlated with HgbA(1c) (r =-0.9366; p < 0.0001) and the peak postmeal plasma glucose concentrations (Pearson r =-7230; p = 0.0003). Our findings suggest that despite good glycemic control, postprandial glucose concentrations are elevated and that 1,5-AG showed a difference between controls and children with T1DM. The data are comparable with previous studies in normal adults and in those with T1DM and T2DM. They support the use of 1,5-AG concentrations, together with HgbA(1c), to evaluate therapy, especially to target postprandial hyperglycemia.