Effects of Miglitol, Acarbose, and Sitagliptin on Plasma Insulin and Gut Peptides in Type 2 Diabetes Mellitus: A Crossover Study

Targeting Leishmania infantum Mannosyl-oligosaccharide glucosidase with natural products: potential pH-dependent inhibition explored through computer-aided drug design

Visceral Leishmaniasis (VL) is a serious public health issue, documented in more than ninety countries, where an estimated 500,000 new cases emerge each year. Regardless of novel methodologies, advancements, and experimental interventions, therapeutic limitations, and drug resistance are still challenging. For this reason, based on previous research, we screened natural products (NP) from Nuclei of Bioassays, Ecophysiology, and Biosynthesis of Natural Products Database (NuBBEDB), Mexican Compound Database of Natural Products (BIOFACQUIM), and Peruvian Natural Products Database (PeruNPDB) databases, in addition to structural analogs of Miglitol and Acarbose, which have been suggested as treatments for VL and have shown encouraging action against parasite's N-glycan biosynthesis. Using computer-aided drug design (CADD) approaches, the potential inhibitory effect of these NP candidates was evaluated by inhibiting the Mannosyl-oligosaccharide Glucosidase Protein (MOGS) from Leishmania infantum, an enzyme essential for the protein glycosylation process, at various pH to mimic the parasite's changing environment. Also, computational analysis was used to evaluate the Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) profile, while molecular dynamic simulations were used to gather information on the interactions between these ligands and the protein target. Our findings indicated that Ocotillone and Subsessiline have potential antileishmanial effects at pH 5 and 7, respectively, due to their high binding affinity to MOGS and interactions in the active center. Furthermore, these compounds were non-toxic and had the potential to be administered orally. This research indicates the promising anti-leishmanial activity of Ocotillone and Subsessiline, suggesting further validation through in vitro and in vivo experiments.

Chromogenic Assay Is More Efficient in Identifying α-Amylase Inhibitory Properties of Anthocyanin-Rich Samples When Compared to the 3,5-Dinitrosalicylic Acid (DNS) Assay

The inhibition of carbohydrate digestion by plant bioactive compounds is a potential dietary strategy to counteract type 2 diabetes. Indeed, inhibition of α-amylase, a key enzyme that carries out the bulk of starch digestion, has been demonstrated for a range of bioactive compounds including anthocyanins; however, sample pigmentation often interferes with measurements, affecting colorimetric assay outcomes. Therefore, the present study compared the performance of a direct chromogenic assay, using 2-chloro-4 nitrophenyl α-D-maltotrioside (CNPG3) as a substrate, with the commonly used 3,5-dinitrosalicylic acid (DNS) assay. The direct chromogenic assay demonstrated a 5-10-fold higher sensitivity to determine α-amylase inhibition in various samples, including acarbose as a reference, pure anthocyanins, and anthocyanin-rich samples. The IC50 values of acarbose presented as 37.6 μg/mL and 3.72 μg/mL for the DNS assay and the direct chromogenic assay, respectively, whereas purified anthocyanins from blackcurrant showed IC50 values of 227.4 µg/mL and 35.0 µg/mL. The direct chromogenic assay is easy to perform, fast, reproducible, and suitable for high-throughput screening of pigmented α-amylase inhibitors.

Production of High-Quality Red Fruit Juices by Athermal Membrane Processes

Membrane-based processes are increasingly used to clarify and concentrate thermo-sensitive fruit juices and plant extracts as alternatives to conventional processes. This work aimed to evaluate the quality of red fruit juices clarified and concentrated by an integrated membrane process with special regard to the preservation of valuable compounds. A red fruit juice obtained from a blend of pomegranate, cactus pear, and red orange juices of Sicilian origin was clarified by microfiltration (MF) and then pre-concentrated up to 33 °Brix by nanofiltration (NF). The pre-concentrated juice was finally concentrated by osmotic distillation (OD) up to 50 and 60 °Brix. Samples of clarified, pre-concentrated, and concentrated juice were analyzed for their physico-chemical composition and in terms of the antioxidant activity and inhibitory activity against α-amylase and lipase. The results clearly confirmed the assumption of a mild fruit juice processing method, allowing us to preserve the original nutritional and functional properties of the fresh juice. In particular, the OD retentate at 60 °Brix resulted the most active sample against pancreatic lipase and α-amylase inhibitory activity with IC50 values of 44.36 and 214.65 μg/mL, respectively.

The Effect of Interventions Led by Community Pharmacists in Primary Care for Adults with Type 2 Diabetes Mellitus on Therapeutic Adherence and HbA1c Levels: A Systematic Review

Type 2 diabetes mellitus has been assessed as a widespread disease globally. Unfortunately, this illness can occasionally go undetected and without symptoms until it reaches the emergency condition, and this can be notably true in patients who do not receive routine medical care. Pharmacists are the foremost accessible health care providers. They can help patients select the most appropriate hypoglycemic management strategy through their experiences. This review aimed to provide an overview of the literature published on community pharmacists' interventions that are currently used and their usefulness in improving patient adherence and glycosylated hemoglobin (HbA1c) levels. Relevant studies were retrieved through a comprehensive search of three databases, PubMed/Medline, Web of Science, and CINAHL (2010 to 2020). In total, 8362 publications were identified. The final protocol was based on the "Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA)". After applying inclusion and exclusion measures, 21 articles were deemed relevant. In pharmacists' interventions in diabetes care, patient education and counseling were the most common intervention methods. Essentially, this systematic review provides evidence and identifies the key features that may predict success in enhancing clinical outcomes and patient adherence to treatment. Based on our findings, we suggest further investigations of the root causes of non-adherence problems.

Inhibitory activities of grape bioactive compounds against enzymes linked with human diseases

A quest for identification of novel, safe and efficient natural compounds, as additives in the modern food and cosmetic industries, has been prompted by concerns about toxicity and side effects of synthetic products. Plant phenolic compounds are one of the most documented natural products due to their multifarious biological applications. Grape (Vitis vinifera) is an important source of phenolic compounds such as phenolic acids, tannins, quinones, coumarins and, most importantly, flavonoids/flavones. This review crisply encapsulates enzyme inhibitory activities of various grape polyphenols towards different key human-ailment-associated enzymes: xanthine oxidase (gout), tyrosinase (hyperpigmentation), α-amylase and α-glucosidase (diabetes mellitus), pancreatic lipase (obesity), cholinesterase (Alzheimer's disease), angiotensin i-converting enzymes (hypertension), α-synuclein (Parkinson's disease) and histone deacetylase (various diseases). The review also depicts the enzyme inhibitory mechanism of various grape polyphenols and briefly discusses their stature as potential therapeutic and drug development candidates. KEY POINTS: • Nineteen major bioactive polyphenols from the grape/grape products and their disease targets are presented • Sixty-two important polyphenols as enzyme inhibitors from grape/grape products are presented • A thorough description and graphical presentation of biological significance of polyphenols against various diseases.

Acarbose is again on the stage

Acarbose is an agent that has been used to treat type 2 diabetes for about 30 years; it prevents postprandial hyperglycemia by inhibiting carbohydrate digestion in the small intestine. Since incretin-based treatments have been preferred over the last 10 to 15 years, the use of acarbose is not as common in treating type 2 diabetes as before. Some studies have shown that acarbose also produces a weight-loss effect by increasing glucagon-like peptide 1 (GLP-1). The positive effect of acarbose on GLP-1, and increasing evidence that it provides cardiovascular protection, suggests that acarbose may again be considered among the first-choice antidiabetic agents, as it was in the 1990s.

Effects of L-arabinose by hypoglycemic and modulating gut microbiome in a high-fat diet- and streptozotocin-induced mouse model of type 2 diabetes mellitus

L-arabinose is a good and healthy food additive. This study was conducted to investigate the effect of L-arabinose in a mouse model of type 2 diabetes mellitus (T2DM) induced by exposure to a high-fat diet (HFD) and streptozotocin (STZ). The model mice received L-arabinose at 20 and 60 mg (kg body weight [bw])^-1 d^-1 , metformin at 300 mg (kg bw)^-1 d^-1 (positive control) or sterile water (control) via oral gavage. Compared with the model group, mice treated with L-arabinose exhibited attenuated symptoms of diabetes mellitus, including a slower rate of body weight loss, increased homeostasis model assessment of β-cell function index levels, decreased blood glucose, alleviation of steatosis, and repair of pancreatic islet cells. L-arabinose also exerted an anti-inflammatory effect and partially mitigated dyslipidemia. A 16S-rRNA sequence analysis of the gut microbiota revealed that at the phylum level, treatment with L-arabinose significantly reduced the ratio of Firmicutes to Bacteroidetes due to a decreased relative abundance of Firmicutes; at the genus level, it reversed the increase in the relative abundance of Allobaculum and the decrease abundance of Oscillospira caused by exposure to an HFD and STZ. And the model mice received L-arabinose at 20 mg (kg bw)^-1 d^-1 had a better effect on improving T2DM than the high-dose group supplemented L-arabinose at 60 mg (kg bw)^-1 d^-1 . These results strongly suggest L-arabinose as an excellent candidate supplement to prevent or treat T2DM. PRACTICAL APPLICATIONS: L-arabinose, xylitol and sucralose are well-known substitutes for sucrose. L-arabinose has been reported to have beneficial effects on hyperglycemia, glycemic index, and fat accumulation. In this study, we found that low-dose (20 mg (kg bw)^-1 d^-1 ) supplementation of L-arabinose significantly improved glucose intolerance and gut microbiota incoordination in T2DM caused by HFD and STZ.

Reduced postprandial bone resorption and greater rise in GLP-1 in overweight and obese individuals after an α-glucosidase inhibitor: a double-blinded randomized crossover trial

When taken with a meal, α-glucosidase inhibitors (α-GI) reduce the rise in postprandial glucose and increase glucagon-like peptide-1 (GLP-1), and this may lower bone turnover. In this study, a salacinol-type α-GI increased GLP-1 and markedly reduced postprandial bone resorption compared to placebo, suggesting it could have implications for bone health.

INTRODUCTION

Animal and clinical trials indicate that α-glucosidase inhibitors attenuate postprandial glycemic indices and increase secretion of GLP-1. In addition, GLP-1 acts on bone by inhibiting resorption. The goal in this study was to determine if a salacinol α-GI alters postprandial bone turnover and can be explained by changes in serum GLP-1.

METHODS

In this double-blind, placebo-controlled crossover study, healthy overweight/obese adults (body mass index 29.0 ± 3.8 kg/m²; 21-59 years; n = 21) received a fixed breakfast and, in random order, were administered Salacia chinensis (SC; 500 mg) or placebo. A fasting blood sample was taken before and at regular intervals for 3 h after the meal. Serum was measured for bone turnover markers, C-terminal telopeptide of type I collagen (CTX) and osteocalcin, and for glycemic indices and gut peptides.

RESULTS

Compared to placebo, SC attenuated the bone resorption marker, CTX, at 60, 90, and 120 min (p < 0.05) after the meal, and decreased osteocalcin, at 180 min (p < 0.05). As expected, SC attenuated the postprandial rise in glucose compared with placebo, whereas GLP-1 was increased at 60 min (p < 0.05) with SC. Serum GLP-1 explained 41% of the variance for change in postprandial CTX (p < 0.05).

CONCLUSION

This study indicates that attenuating postprandial glycemic indices, with an α-GI, markedly decreases postprandial bone resorption and can be explained by the rise in GLP-1. Future studies should determine whether longer term α-GI use benefits bone health.

S100 Genes are Highly Expressed in Peripheral Leukocytes of Type 2 Diabetes Mellitus Patients Treated with Dietary Therapy

Background and Objectives

We demonstrated that the mRNA induction of S100s in rat peripheral leukocytes by severe hyperglycemia was reduced by inhibiting postprandial hyperglycemia. Here, we compared inflammatory gene expression in peripheral leukocytes between type 2 diabetes mellitus (T2DM) patients undergoing dietary therapy alone and healthy volunteers, and between T2DM patients undergoing dietary therapy alone and those undergoing such therapy in combination with drug therapy using the α-glucosidase inhibitor miglitol.

Methods

T2DM patients who had undertaken dietary therapy alone or in combination with drug therapy using miglitol for ≥ 8 weeks and healthy volunteers were subjected to a meal tolerance test and glucose concentration, neutrophil elastase concentration, and mRNA expression analyses of peripheral leukocytes by microarray and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) immediately before and 180 min after a meal.

Results

Blood glucose concentrations 60 min after a meal were lower in T2DM patients with dietary + miglitol therapy than in those with dietary therapy alone. Neutrophil elastase concentrations at 60 and 120 min after a meal were lower in T2DM patients with dietary + miglitol therapy than in those with dietary therapy alone. Expression levels of S100A8 in a fasting state and S100A6, S100A8, and S100A9 180 min after a meal were higher in T2DM patients with dietary therapy alone than in healthy volunteers. Expression levels of S100A12 in a fasting state and 180 min after a meal were higher in T2DM patients with dietary therapy alone than in T2DM patients with dietary + miglitol therapy.

Conclusions

S100 genes were more highly expressed in T2DM patients with dietary therapy than in healthy volunteers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40268-020-00334-z.

Factors associated with improvement in waist-to-height ratio among newly diagnosed type 2 diabetes patients treated with acarbose or metformin: A randomized clinical trial study

BACKGROUND

The waist-to-height ratio (WHtR) is a promising anthropometric measure used to evaluate cardiovascular risk in diabetes and metabolic syndrome patients. The metformin and acarbose in Chinese as the initial hypoglycaemic treatment trial demonstrated that acarbose and metformin reduced the WHtR after 24 wk of treatment.

AIM

To investigate the factors associated with a decrease in the WHtR in newly diagnosed Chinese type 2 diabetes patients receiving acarbose or metformin monotherapy.

METHODS

At 24 wk, 343 patients in the acarbose treatment and 333 patients in the metformin treatment were included in this analysis. On the basis of the reduction in the WHtR, these participants were divided into the following two groups: Low ΔWHtR group and high ΔWHtR group. Metabolic and related parameters associated with a high ΔWHtR were investigated using univariate and multivariate logistic regression analyses.

RESULTS

A significant decrease in the WHtR was observed in both treatment groups (acarbose: -0.015, 95% confidence interval [CI]: -0.018 to -0.012, P < 0.001; metformin: -0.013, 95%CI: -0.016 to -0.010, P < 0.001). In both the acarbose and metformin groups, the WHtR of the women was more likely to be reduced than that of the men. In the acarbose group, a lower baseline area under the curve of glucagon-like peptide 1 (AUCGLP-1) was associated with a high ΔWHtR (odds ratio [OR] = 0.796, P < 0.001), while a higher baseline AUCGLP-1 was associated with a high ΔWHtR in the patients treated with metformin (OR = 1.133, P = 0.025). Regarding the changes from baseline, an increase in AUCGLP-1 was associated with a high ΔWHtR in the acarbose (OR = 1.121, P = 0.016) but not metformin group. A higher reduction in high-density lipoprotein cholesterol/non-high-density lipoprotein cholesterol was also associated with a high ΔWHtR in the acarbose arm (OR = 20.735, P = 0.001). In the metformin arm, a higher reduction in fasting plasma glucose (OR = 0.843, P = 0.039) and total cholesterol was associated with a high ΔWHtR (OR = 0.743, P = 0.013).

CONCLUSION

A lower glucagon-like peptide 1 level and higher increase in glucagon-like peptide 1 are associated with a high reduction in the WHtR in newly diagnosed Chinese diabetes patients receiving treatment with acarbose.

Carbohydrate Hydrolase-Inhibitory Activity of Juice-Based Phenolic Extracts in Correlation to Their Anthocyanin/Copigment Profile

Red fruits and their juices are rich sources of polyphenols, especially anthocyanins. Some studies have shown that such polyphenols can inhibit enzymes of the carbohydrate metabolism, such as α-amylase and α-glucosidase, that indirectly regulate blood sugar levels. The presented study examined the in vitro inhibitory activity against α-amylase and α-glucosidase of various phenolic extracts prepared from direct juices, concentrates, and purees of nine different berries which differ in their anthocyanin and copigment profile. Generally, the extracts with the highest phenolic content-aronia (67.7 ± 3.2 g GAE/100 g; cyanidin 3-galactoside; chlorogenic acid), pomegranate (65.7 ± 7.9 g GAE/100 g; cyanidin 3,5-diglucoside; punicalin), and red grape (59.6 ± 2.5 g GAE/100 g; malvidin 3-glucoside; quercetin 3-glucuronide)-showed also one of the highest inhibitory activities against α-amylase (326.9 ± 75.8 μg/mL; 789.7 ± 220.9 μg/mL; 646.1 ± 81.8 μg/mL) and α-glucosidase (115.6 ± 32.5 μg/mL; 127.8 ± 20.1 μg/mL; 160.6 ± 68.4 μg/mL) and, partially, were even more potent inhibitors than acarbose (441 ± 30 μg/mL; 1439 ± 85 μg/mL). Additionally, the investigation of single anthocyanins and glycosylated flavonoids demonstrated a structure- and size-dependent inhibitory activity. In the future in vivo studies are envisaged.

Probing the characteristics and biofunctional effects of disease-affected cells and drug response via machine learning applications

Drug-induced transformations in disease characteristics at the cellular and molecular level offers the opportunity to predict and evaluate the efficacy of pharmaceutical ingredients whilst enabling the optimal design of new and improved drugs with enhanced pharmacokinetics and pharmacodynamics. Machine learning is a promising in-silico tool used to simulate cells with specific disease properties and to determine their response toward drug uptake. Differences in the properties of normal and infected cells, including biophysical, biochemical and physiological characteristics, plays a key role in developing fundamental cellular probing platforms for machine learning applications. Cellular features can be extracted periodically from both the drug treated, infected, and normal cells via image segmentations in order to probe dynamic differences in cell behavior. Cellular segmentation can be evaluated to reflect the levels of drug effect on a distinct cell or group of cells via probability scoring. This article provides an account for the use of machine learning methods to probe differences in the biophysical, biochemical and physiological characteristics of infected cells in response to pharmacokinetics uptake of drug ingredients for application in cancer, diabetes and neurodegenerative disease therapies.

The Mechanism of Metabolic Influences on the Endogenous GLP-1 by Oral Antidiabetic Medications in Type 2 Diabetes Mellitus

Incretin-based therapy is now a prevalent treatment option for patients with type 2 diabetes mellitus (T2DM). It has been associated with considerably good results in the management of hyperglycemia with cardiac or nephron-benefits. For this reason, it is recommended for individuals with cardiovascular diseases in many clinical guidelines. As an incretin hormone, glucagon-like peptide-1 (GLP-1) possesses multiple metabolic benefits such as optimizing energy usage, maintaining body weight, β cell preservation, and suppressing neurodegeneration. However, recent studies indicate that oral antidiabetic medications interact with endogenous or exogenous GLP-1. Since these drugs are transported to distal intestine portions, there are concerns whether these oral drugs directly stimulate intestinal L cells which release GLP-1, or whether they do so via indirect inhibition of the activity of dipeptidyl peptidase-IV (DPP-IV). In this review, we discuss the metabolic relationships between oral antihyperglycemic drugs from the aspect of gut, microbiota, hormones, β cell function, central nervous system, and other cellular mechanisms.

Postprandial Reactive Hypoglycemia

Reactive hypoglycemia (RH) is the condition of postprandially hypoglycemia occurring 2-5 hours after food intake. RH is clinically seen in three different forms as follows: idiopathic RH (at 180 min), alimentary (within 120 min), and late RH (at 240–300 min). When the first-phase insulin response decreases, firstly, blood glucose starts to rise after the meal. This leads to late but excessive secretion of the second-phase insulin secretion. Thus, late reactive hypoglycemia occurs. Elevated insulin levels also cause down-regulation of the insulin post-receptor on the muscle and fat cells, thus decreasing insulin sensitivity. The cause of the increase in insulin sensitivity in IRH at 3 h is not completely clear. However, there is a decrease in insulin sensitivity in late reactive hypoglycaemia at 4 or 5 hours. Thus, patients with hypoglycemia at 4 or 5 h who have a family history of diabetes and obesity may be more susceptible to diabetes than patients with hypoglycemia at 3 h. We believe that some cases with normal glucose tolerance in OGTT should be considered as prediabetes at <55 or 60 mg/dl after 4-5 hours after OGTT. Metformin and AGI therapy may be recommended if there is late RH with IFG. Also Metformin, AGİ, TZD, DPP-IVInhibitors, GLP1RA therapy may be recommended if there is late RH with IGT. As a result, postprandial RH (<55 or 60 mg/dl), especially after 4 hours may predict diabetes. Therefore, people with RH along with weight gain and with diabetes history in the family will benefit from a lifestyle modification as well as the appropriate antidiabetic approach in the prevention of diabetes.

In silico evaluation of condensed and hydrolysable tannins as inhibitors of pancreatic α-amylase

Amylases are interesting targets for antidiabetic drugs because their inhibition is able to lower glycaemia without the need of hormonal control, as promoted by insulin or glibenclamide. In this context, the comparison between the binding features of α-amylases with their substrate and known inhibitors may provide insights aiming at the discovery of new antidiabetic drugs. In this work, the structure of the porcine pancreatic α-amylase was modelled with the acarbose pentasaccharide inhibitor, and used in structure-based virtual screening simulations based on a library containing the structures of amylose (AMY), acarbose (ACA) and the more representative structures of condensed tannin (CTN) and hydrolysable tannin (HTN). After validation of the methodology by redocking (mean rmsd ~ 0.8 Å), the scores provided by programs AutoDock/Molegro were contradictory (- 1.5/- 23.3; - 3.5/- 24.6; - 4.3/- 14.6; -/- 19.5 for AMY, ACA, CTN and HTN respectively), indicating that a more sensitive methodology was necessary. The ΔG_binding was calculated by the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method, which indicated that the HTN, ACA and CTN had higher affinities for the enzyme regarding the AMY substrate, with values of - 350.0, - 346.2, - 320.5 and - 209.2 kJ mol^-1, respectively. The predicted relative affinities of HTN and CTN are in agreement with those obtained experimentally. The results provided useful information for the characterization of tannin binding to α-amylase, which can be applied in future studies aiming at finding new hypoglycaemic molecules among natural products.

Augmented GLP-1 Secretion as Seen After Gastric Bypass May Be Obtained by Delaying Carbohydrate Digestion

CONTEXT

Exaggerated postprandial glucagon-like peptide-1 (GLP-1) secretion seems important for weight loss and diabetes remission after Roux-en-Y gastric bypass (RYGB) and may result from carbohydrate absorption in the distal small intestine.

OBJECTIVE

To investigate distal [GLP-1; peptide YY (PYY)] and proximal [glucose-dependent insulinotropic polypeptide (GIP)] gut hormone secretion in response to carbohydrates hydrolyzed at different rates. We hypothesized that slow digestion restricts proximal absorption, facilitating distal delivery of carbohydrates and thereby enhanced GLP-1 secretion in unoperated individuals, whereas this may not apply after RYGB.

DESIGN

Single-blinded, randomized, crossover study.

SETTING

Hvidovre Hospital, Hvidovre, Denmark.

PARTICIPANTS

Ten RYGB-operated patients and 10 unoperated matched subjects.

INTERVENTIONS

Four separate days with ingestion of different carbohydrate loads, either rapidly/proximally digested (glucose plus fructose; sucrose) or slowly/distally digested (isomaltulose; sucrose plus acarbose).

MAIN OUTCOME MEASURES

GLP-1 secretion (area under the curve above baseline). Secondary outcomes included PYY and GIP.

RESULTS

Isomaltulose enhanced secretion of GLP-1 nearly threefold (P = 0.02) and PYY ninefold (P = 0.08) compared with sucrose in unoperated subjects but had a modest effect after RYGB. Acarbose failed to increase sucrose induced GLP-1 secretion in unoperated subjects and diminished the responses by 50% after RYGB (P = 0.03). In both groups, GIP secretion was reduced by isomaltulose and even more so by sucrose plus acarbose when compared with sucrose intake.

CONCLUSIONS

GLP-1 secretion depends on the rate of carbohydrate digestion, but in a different manner after RYGB. Enhanced GLP-1 secretion is central after RYGB, but it may also be obtained in unoperated individuals by delaying hydrolysis of carbohydrates, pushing their digestion and absorption distally in the small intestine.

Acarbose Add-on Therapy in Patients with Type 2 Diabetes Mellitus with Metformin and Sitagliptin Failure: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study

BACKGROUND

We evaluated the efficacy and safety of acarbose add-on therapy in Korean patients with type 2 diabetes mellitus (T2DM) who are inadequately controlled with metformin and sitagliptin.

METHODS

A total of 165 subjects were randomized to metformin and sitagliptin (Met+Sita, n=65), metformin, sitagliptin, and acarbose (Met+Sita+Acarb, n=66) and sitagliptin and acarbose (Sita+Acarb, exploratory assessment, n=34) therapy in five institutions in Korea. After 16 weeks of acarbose add-on or metformin-switch therapy, a triple combination therapy was maintained from week 16 to 24.

RESULTS

The add-on of acarbose (Met+Sita+Acarb group) demonstrated a 0.44%±0.08% (P<0.001 vs. baseline) decrease in glycosylated hemoglobin (HbA1c) at week 16, while changes in HbA1c were insignificant in the Met+Sita group (-0.09%±0.10%, P=0.113). After 8 weeks of triple combination therapy, HbA1c levels were comparable between Met+Sita and Met+Sita+Acarb group (7.66%±0.13% vs. 7.47%±0.12%, P=0.321). Acarbose add-on therapy demonstrated suppressed glucagon secretion (area under the curve of glucagon, 4,726.17±415.80 ng·min/L vs. 3,314.38±191.63 ng·min/L, P=0.004) in the absence of excess insulin secretion during the meal tolerance tests at week 16 versus baseline. The incidence of adverse or serious adverse events was similar between two groups.

CONCLUSION

In conclusion, a 16-week acarbose add-on therapy to metformin and sitagliptin, effectively lowered HbA1c without significant adverse events. Acarbose might be a good choice as a third-line therapy in addition to metformin and sitagliptin in Korean subjects with T2DM who have predominant postprandial hyperglycemia and a high carbohydrate intake.

Activity-Guided Fractionation of Red Fruit Extracts for the Identification of Compounds Influencing Glucose Metabolism

An activity-guided search for compounds influencing glucose metabolism in extracts from aronia (Aronia melanocarpa, A.), pomegranate (Punica granatum L., P.), and red grape (Vitis vinifera, RG) was carried out. The three extracts were fractionated by means of membrane chromatography to separate the anthocyanins from other noncolored phenolic compounds (copigments). In addition, precipitation with hexane was performed to isolate the polymers (PF). The anthocyanin and copigment fractions (AF, CF) of aronia, pomegranate, and red grape were furthermore fractionated with high-performance countercurrent chromatography (HPCCC) and the subfractions were characterized by HPLC-PDA-MS/MS analyses. Each of the (sub-)fractions was examined by in vitro-tests, i.e., the inhibition of the activity of α-amylase and α-glucosidase. On the basis of this screening, several potent inhibitors of the two enzymes could be identified, which included flavonols (e.g., quercetin), ellagitannins (e.g., pedunculagin), and anthocyanins (e.g., delphinidin-3-glucoside and petunidin-3-glucoside). In the α-glucosidase assay all of the examined fractions and subfractions of the fruit extracts were more active than the positive control acarbose.

Appetite and Gut Hormones Response to a Putative α-Glucosidase Inhibitor, Salacia Chinensis, in Overweight/Obese Adults: A Double Blind Randomized Controlled Trial

Animal studies indicate Salacia reduces body weight, possibly due to its α-glucosidase inhibitor (α-GI) properties, but this has not been examined previously. In this study, a randomized, placebo-controlled, three-way cross-over design was used to evaluate whether Salacia Chinensis (SC) reduces appetite in healthy overweight/obese individuals (body mass index 28.8 ±3.6 kg/m²; 32 ± 12 years). Forty-eight participants were fasted overnight and consumed a dose of SC (300 or 500 mg) or placebo with a fixed breakfast meal at each visit. Appetite sensations, glycemic indices and gastrointestinal peptides were measured. Results indicated that SC had no effect on postprandial appetite. However, in women, hunger was reduced by SC compared to placebo at multiple time points (300 mg; p < 0.05), but not in men. Area under the curve (AUC) for serum glucose, insulin and amylin was attenuated with SC compared to placebo (p < 0.05). Glucagon like peptide-1 had two peaks after the meal, but the AUC did not differ between groups. The AUC of peak areas for peptide YY and ghrelin were greater for SC than placebo (p < 0.05). These findings indicate that Salacia decreases glycemic indices supporting its role as an α-GI, and affects certain gastrointestinal peptides suggesting it may be an appetite modulator.

A randomized clinical trial of the safety and efficacy of sitagliptin in patients with type 2 diabetes mellitus inadequately controlled by acarbose alone

OBJECTIVE

To evaluate the safety and efficacy of sitagliptin when added to the treatment of patients with type 2 diabetes mellitus (T2DM) and inadequate glycemic control on acarbose monotherapy.

RESEARCH DESIGN AND METHODS

This was a multicenter, randomized, placebo-controlled, double-blind clinical trial. Patients (N = 381) with T2DM and inadequate glycemic control (glycated hemoglobin [HbA1c] ≥ 7.0% and ≤10.0%) on acarbose monotherapy (at least 50 mg three times daily) were randomized in a 1:1 ratio to receive the addition of sitagliptin 100 mg or matching placebo once daily for 24 weeks.

MAIN OUTCOME MEASURES

Changes from baseline in HbA1c and fasting plasma glucose (FPG) at Week 24.

RESULTS

The mean baseline HbA1c in randomized patients was 8.1%. At Week 24, the placebo-controlled, least squares mean changes from baseline (95% confidence interval) in HbA1c and FPG in the sitagliptin group were -0.62% and -0.8 mmol/L (p < .001), respectively. At Week 24, 37.8% of patients in the sitagliptin group were at HbA1c goal of <7% compared with 17.2% in the placebo group (p < .001). Sitagliptin was generally well tolerated, and there were no significant between-group differences in prespecified safety parameters (symptomatic hypoglycemia, diarrhea, abdominal pain, nausea, vomiting). A higher incidence of serious adverse events was observed in the sitagliptin group (5.2%) relative to placebo (0.5%); all but one, in the sitagliptin group, were not considered related to drug.

CONCLUSIONS

Sitagliptin was generally well tolerated and provided statistically superior and clinically meaningful improvements in glycemic control after 24 weeks of treatment compared to placebo when added to treatment of patients with inadequate glycemic control on acarbose monotherapy. Clinicaltrials.gov: NCT01177384.

Effect of miglitol on the suppression of nonalcoholic steatohepatitis development and improvement of the gut environment in a rodent model

BACKGROUND

The gut environment has been considered to play a role in the development of nonalcoholic steatohepatitis (NASH). α-glucosidase inhibitors (α-GIs) delay carbohydrate absorption and may change the gut environment. We considered that the protective effect of α-GIs against NASH development is related to changes in the gut environment and thus investigated the effects of miglitol, an α-GI, on NASH development and the gut environment.

METHODS

Mice were divided into three groups and fed a normal chow diet (NCD), a high-fat high-sucrose diet (HFHSD), or HFHSD plus 0.04% miglitol (HFHSD plus M) for 12 weeks.

RESULTS

Insulin resistance developed more in the HFHSD group than in the NCD group, whereas it was suppressed in the HFHSD plus M group. NASH was evaluated histologically, biochemically, and on the basis of messenger RNA expression levels. Miglitol treatment suppressed HFHSD-induced NASH development with the suppression of hepatic Toll-like receptor 4 expression, increased glucagon-like peptide 1 (GLP-1) concentration, and reduced lipopolysaccharide concentration in portal plasma. Regarding the gut environment, the intestinal transit time was shortened and colon inflammation was suppressed in the HFHSD plus M group compared with the HFHSD group. Regarding the gut microbiota, the abundances of Erysipelotrichaceae and Coriobacteriaceae were increased in the HFHSD group compared with the NCD group, whereas the increase was suppressed in the HFHSD plus M group.

CONCLUSIONS

We demonstrated that miglitol has a protective effect against HFHSD-induced NASH development. The increased GLP-1 secretion and the suppression of endotoxemia, associated with the changes in the gut environment, including the gut microbiota, could contribute to the underlying mechanisms.

Pharmacology and therapeutic implications of current drugs for type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a global epidemic that poses a major challenge to health-care systems. Improving metabolic control to approach normal glycaemia (where practical) greatly benefits long-term prognoses and justifies early, effective, sustained and safety-conscious intervention. Improvements in the understanding of the complex pathogenesis of T2DM have underpinned the development of glucose-lowering therapies with complementary mechanisms of action, which have expanded treatment options and facilitated individualized management strategies. Over the past decade, several new classes of glucose-lowering agents have been licensed, including glucagon-like peptide 1 receptor (GLP-1R) agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors and sodium/glucose cotransporter 2 (SGLT2) inhibitors. These agents can be used individually or in combination with well-established treatments such as biguanides, sulfonylureas and thiazolidinediones. Although novel agents have potential advantages including low risk of hypoglycaemia and help with weight control, long-term safety has yet to be established. In this Review, we assess the pharmacokinetics, pharmacodynamics and safety profiles, including cardiovascular safety, of currently available therapies for management of hyperglycaemia in patients with T2DM within the context of disease pathogenesis and natural history. In addition, we briefly describe treatment algorithms for patients with T2DM and lessons from present therapies to inform the development of future therapies.

Single-dose acarbose decreased glucose-dependent insulinotropic peptide and glucagon levels in Chinese patients with newly diagnosed type 2 diabetes mellitus after a mixed meal

BACKGROUND

Acarbose slows down the intestinal absorption of carbohydrates, but its effects on the secretion of incretins are still poorly known. This study aimed to examine the effects of single-dose acarbose on the secretion of incretins in patients with newly diagnosed type 2 diabetes mellitus (T2DM).

METHODS

In this pilot study, twenty-three patients diagnosed with T2DM were randomly assigned to the oral glucose tolerance test (OGTT) group (n = 11) and the mixed meal test (MMT) group (n = 12). Fourteen subjects with normal OGTT were included as controls. Plasma glucose, insulin, glucagon, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic peptide (GIP) were measured at 0 (fasting), 15, 30, 60, 90, and 120 min after nutrient load. A week later, controls underwent MMT, the OGTT group underwent OGTT receiving 100 mg acarbose, and the MMT group underwent MMT receiving 100 mg acarbose. The same blood markers were measured again.

RESULTS

No significant difference was observed in the OGTT group before and after administering acarbose. In the MMT group, postprandial levels of glucose (P < 0.01), insulin (P < 0.01), glucagon at 15 min (P < 0.05), glucagon area under the curve (AUC) (P < 0.05), GIP levels at 30 min (P < 0.05), and GIP AUC (P < 0.05) were decreased after receiving acarbose with a mixed meal, but GLP-1 levels and GLP-1 AUC did not change.

CONCLUSIONS

Single-dose acarbose could reduce the secretion of GIP and glucagon after a mixed meal in patients with newly diagnosed T2DM. The influence of acarbose on incretin levels could be related to the types of carbohydrate being consumed.

TRIAL REGISTRATION

This study was registered with the Chinese Clinical Trial Registry (Registration Number: ChiCTR-TRC-14004260 , Date of Registration: 2014-01-19).