Postprandial hyperglycemia and endothelial function in type 2 diabetes: focus on mitiglinide

Korean Red Ginseng Extract Powder Mitigates Fasting And Postprandial Hyperglycemia in Type 2 Diabetic Mice

Type 2 diabetes mellitus (T2DM) involves insulin resistance and elevated blood sugar levels, causing complications. Red ginseng extract powder (RGEP) from Panax ginseng Meyer shows promise for diabetes treatment. However, its efficacy in managing T2DM remains unclear. Therefore, this study aims to evaluate the effectiveness of RGEP in a mouse model of T2DM. The efficacy of RGEP in treating T2DM was assessed in db/db mice. Mice were divided into seven groups: control, db/db, metformin, and RGEP at 50, 100, 200, and 400 mg/kg. Administered orally for 9 weeks, RGEP effects on glucose regulation and insulin sensitivity were assessed through various metabolic parameters. In addition, mRNA expression levels of genes associated with hepatic gluconeogenesis and insulin sensitivity were examined. Fasting blood sugar showed a significant decrease in all RGEP concentration groups, but OGTT and insulin tolerance test showed a significant decrease at the RGEP concentration of 400 mg/kg, indicating enhanced glycemic control. Moreover, RGEP dose-dependently decreased serum glucose, HbA1c levels, and homeostatic model assessment of insulin resistance values, suggesting its effectiveness in reducing insulin resistance in db/db mice. Furthermore, RGEP downregulated mRNA expression of key components in the gluconeogenesis pathway (G6Pase, FOXO1, GLUT4, and PEPCK), insulin sensitivity (leptin, insulin1, PTP1B, GLP-1, and DPP-4), and mitochondria energy metabolism (PGC1) in either the liver or pancreas, while simultaneously upregulating GLP-1 expression. In conclusion, these findings highlight the potential of RGEP as a complementary therapy for T2DM, indicating therapeutic efficacy in managing diabetic complications through improved metabolic parameters.

The efficacy of switching basal-bolus insulin therapy to basal insulin-supported oral therapy with a glinide and an α-glucosidase inhibitor in patients with type 2 diabetes depends on insulin secretory capacity, but not on blood glucose profiles and insulin dosages prior to the switching

Aims

We aimed to identify patients who would benefit from basal insulin-supported oral therapy (BOT) with a glinide and an α-glucosidase inhibitor (a fixed-dose combination tablet of mitiglinide 10 mg and voglibose 0.2 mg) in Japanese type 2 diabetic patients.

Methods

Patients who were hospitalized to improve hyperglycemia received basal-bolus insulin therapy. After the reduction of glucose toxicity, a 75 g oral glucose tolerance test and a glucagon test were performed. Thereafter, the basal-bolus insulin therapy was switched to BOT with mitiglinide, followed by further addition of voglibose. Interstitial glucose levels were continuously monitored throughout the study period. Diurnal glucose profile was recorded and analyzed. Patients were divided into two groups according to whether their percentage of time in range (TIR, 70-180 mg/dL) under BOT with mitiglinide/voglibose was higher than 70% or not, and the differences in clinical characteristics between the groups were analyzed.

Results

Twenty patients were enrolled, and 19 of them completed the study. BOT with mitiglinide/voglibose achieved ≥ 70% of TIR in thirteen patients. The area under the curve of serum C-peptide levels during the oral glucose tolerance test was significantly higher in the patients with ≥ 70% of TIR. The daily insulin dosages and blood glucose profiles were comparable between the two groups.

Conclusions

The efficacy of BOT with mitiglinide/voglibose depended on residual insulin secretory abilities. This therapy would be a useful therapeutic option for patients with type 2 diabetes.

Can Antidiabetic Medications Affect Telomere Length in Patients with Type 2 Diabetes? A Mini-Review

The fight against aging is an eternal pursuit of humankind. The aging rate of patients with type 2 diabetes mellitus (T2DM) is higher than that of healthy individuals. Reducing the aging rate of patients with T2DM and extending their life expectancy are challenges that endocrinologists are eager to overcome. Many studies have shown that antidiabetic medications have potent anti-aging potential. Telomeres are repetitive DNA sequences located at the ends of chromosomes, and telomere shortening is a hallmark of aging. This review summarizes clinical trials that have explored the association between antidiabetic medications and telomere length (TL) in patients with T2DM and explore the mystery of delaying aging in patients with T2DM from the perspective of telomeres. Various antidiabetic medications may have different effects on TL in patients with T2DM. Metformin and sitagliptin may protect telomeres in patients with T2DM, while exogenous insulin may promote telomere shortening in patients with T2DM. The effect of acarbose and glyburide on TL in patients with T2DM is still uncertain due to the absence of evidence from longitudinal studies.

Lipid profiles and their relation to glycemic control in Saudi Arabia: The role of altitudes and environmental factor

Background

The height from sea levels, environmental factors, human-environment interactions, and lifestyle significantly influence the lipid profile and glycemic control of a population.

Objective

This study aims to explore the influence of altitude on lipid profiles and glycemic control among the Saudi population at sea level and high altitude.

Methods

In this retrospective cross-sectional study, a large dataset of patients of both gender and over 30 years old attending internal medicine clinics from two different regions at different heights from sea level, Jeddah (sea level) and Asir region (high altitudes) and referred to commercial laboratories for glycated haemoglobin (HbA1c) and lipids profile.

Results

Compared to the Asir region, the Jeddah region had significantly higher mean values for fasting blood sugar (FBG), total cholesterol (TC), low-density lipoprotein (LDL-C), and triglycerides (TG) (P < 0.05). Every 1 mg/dL increase in FBG results in a 0.662 mg/dL increase in TG from the Jeddah region. However, it was a 0.318 mg/dL increase in TG from the Asir region. HbA1c demonstrated a significant (P < 0.05) strong positive correlation with TC, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and lipid ratio. FBG levels were also associated with a high level of TC/HDL-C (β = 0.137 95% confidence interval [CI]: 0.11-0.21; P < 0.05), LDL-C/high-density lipoprotein cholesterol (HDL-C) (β = 0.50; 95% CI: 0.31-1.49; P < 0.05), and TG/HDL-C (β = 0.14; 95% CI = 0.12-0.15; P < 0.05) in Jeddah region. However, significantly high blood pressure was observed in the population from high altitudes.

Conclusion

Our results demonstrated a significant positive correlation between lipid profile and glycemic control with high prevalence at sea level.

Dyslipidemia, Diabetes and Atherosclerosis: Role of Inflammation and ROS-Redox-Sensitive Factors

The prevalence of diabetes is growing at an alarming rate with increased disability, morbidity, and often premature mortality because of the various complications of this disorder. Chronic hyperglycemia, dyslipidemia, and other metabolic alterations lead to the development and progression of macro- and microvascular complications of diabetes including cardiovascular, retinal and kidney disease. Despite advances in glucose and lipid lowering treatments, a large number of diabetic individuals develop one or more types of these complications, ultimately leading to end-organ damage over the time. Atherosclerosis is the major macro-vascular complications of diabetes and the primary underlying cause of cardiovascular disease (CVD) posing heavy burden on the health care system. In this review, we discuss the involvement of dyslipidemia in the progression of atherosclerosis by activating the pro-inflammatory cytokines and oxidative stress-related factors. In addition, we also provide information on various pharmacological agents that provides protection against diabetic atherosclerosis by reducing inflammation and oxidative stress.

The anti-diabetic drug alogliptin induces vasorelaxation via activation of Kv channels and SERCA pumps

In the present study, we investigated the vasorelaxant effects of alogliptin, an oral antidiabetic drug in the dipeptidyl peptidase-4 (DPP-4) inhibitor class, using phenylephrine (Phe)-induced pre-contracted aortic rings. Alogliptin induced vasorelaxation in a dose-dependent manner. Pre-treatment with the voltage-dependent K⁺ (Kv) channel inhibitor 4-aminopyridine (4-AP) significantly decreased the vasorelaxant effect of alogliptin, whereas pre-treatment with the inwardly rectifying K⁺ (Kir) channel inhibitor Ba²⁺, ATP-sensitive K⁺ (K_ATP) channel inhibitor glibenclamide, and large-conductance Ca²⁺-activated K⁺ (BK_Ca) channel inhibitor paxilline did not alter the effects of alogliptin. Although pre-treatment with the Ca²⁺ channel inhibitor nifedipine did not affect the vasorelaxant effect of alogliptin, pre-treatment with the sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitors thapsigargin and cyclopiazonic acid effectively attenuated the vasorelaxant response of alogliptin. Neither cGMP/protein kinase G (PKG)-related signaling pathway inhibitors (guanylyl cyclase inhibitor ODQ and PKG inhibitor KT 5823) nor cAMP/protein kinase A (PKA)-related signaling pathway inhibitors (adenylyl cyclase inhibitor SQ 22536 and PKA inhibitor KT 5720) reduced the vasorelaxant effect of alogliptin. Similarly, the vasorelaxant effect of alogliptin was not changed by endothelium removal or pre-treatment with the nitric oxide (NO) synthase inhibitor L-NAME or the small- and intermediate-conductance Ca²⁺-activated K⁺ (SK_Ca and IK_Ca) channel inhibitors apamin and TRAM-34. Based on these results, we suggest that alogliptin induced vasorelaxation in rabbit aortic smooth muscle by activating Kv channels and the SERCA pump independent of other K⁺ channels, cGMP/PKG-related or cAMP/PKA-related signaling pathways, and the endothelium.

Histone deacetylase 5 regulates interleukin 6 secretion and insulin action in skeletal muscle

OBJECTIVE

Physical exercise training is associated with increased glucose uptake in skeletal muscle and improved glycemic control. HDAC5, a class IIa histone deacetylase, has been shown to regulate transcription of the insulin-responsive glucose transporter GLUT4 in cultured muscle cells. In this study, we analyzed the contribution of HDAC5 to the transcriptional network in muscle and the beneficial effect of muscle contraction and regular exercise on glucose metabolism.

METHODS

HDAC5 knockout mice (KO) and wild-type (WT) littermates were trained for 8 weeks on treadmills, metabolically phenotyped, and compared to sedentary controls. Hdac5-deficient skeletal muscle and cultured Hdac5-knockdown (KD) C2C12 myotubes were utilized for studies of gene expression and glucose metabolism. Chromatin immunoprecipitation (ChIP) studies were conducted to analyze Il6 promoter activity using H3K9ac and HDAC5 antibodies.

RESULTS

Global transcriptome analysis of Hdac5 KO gastrocnemius muscle demonstrated activation of the IL-6 signaling pathway. Accordingly, knockdown of Hdac5 in C2C12 myotubes led to higher expression and secretion of IL-6 with enhanced insulin-stimulated activation of AKT that was reversed by Il6 knockdown. Moreover, Hdac5-deficient myotubes exhibited enhanced glucose uptake, glycogen synthesis, and elevated expression levels of the glucose transporter GLUT4. Transcription of Il6 was further enhanced by electrical pulse stimulation in Hdac5-deficient C2C12 myotubes. ChIP identified a ∼1 kb fragment of the Il6 promoter that interacts with HDAC5 and demonstrated increased activation-associated histone marker AcH3K9 in Hdac5-deficient muscle cells. Exercise intervention of HDAC5 KO mice resulted in improved systemic glucose tolerance as compared to WT controls.

CONCLUSIONS

We identified HDAC5 as a negative epigenetic regulator of IL-6 synthesis and release in skeletal muscle. HDAC5 may exert beneficial effects through two different mechanisms, transcriptional control of genes required for glucose disposal and utilization, and HDAC5-dependent IL-6 signaling cross-talk to improve glucose uptake in muscle in response to exercise.

Type 2 diabetes mellitus: pathogenesis and genetic diagnosis

Type 2 diabetes mellitus (T2DM) is a heterogeneous condition that is related to both defective insulin secretion and peripheral insulin resistance. Beta cells are the major organ for secreting insulin hence, it is important to maintain an adequate beta-cell mass in response to various changes. Insulin resistance is a major cause of T2DM leads to elevated free fatty acid (FFA) levels which increases beta-cell mass and insulin secretion to compensate for insulin insensitivity. Chronic increase of plasma FFA levels results in disturbances in lipid metabolism, which contributes to decreased beta-cell function and lipotoxicity thus promoting T2DM. In the present review, we have discussed the process of beta-cell destruction, the role of genes in contributing to the fast increase in the progression of T2DM in detail. More than 130 variants in various T2DM susceptibility and candidate genes have been discovered to be associated with T2DM. Still, these variants elucidate only a small amount of total heritability of T2DM. Further, there is also an inventory of presently used therapeutic tools and a review of novel therapeutic approaches like incretin-based therapies or sodium-glucose transporter-2 inhibitors. Additionally, providing a concise but comprehensive update, this review will be essential to every clinician involved in the treatment of diabetes mellitus.

Synthesis and Comparative Structure-Activity Study of Carbohydrate-Based Phenolic Compounds as α-Glucosidase Inhibitors and Antioxidants

Twenty-one natural and unnatural phenolic compounds containing a carbohydrate moiety were synthesized and their structure-activity relationship (SAR) was evaluated for α-glucosidase inhibition and antioxidative activity. Varying the position of the galloyl unit on the 1,5-anhydro-d-glucitol (1,5-AG) core resulted in changes in the α-glucosidase inhibitory activity and notably, particularly strong activity was demonstrated when the galloyl unit was present at the C-2 position. Furthermore, increasing the number of the galloyl units significantly affected the α-glucosidase inhibition, and 2,3,4,6-tetra-galloyl-1,5-AG (54) and 2,3,4,6-tetra-galloyl-d-glucopyranose (61) exhibited excellent activities, which were more than 13-fold higher than the α-glucosidase inhibitory activity of acertannin (37). Moreover, a comparative structure-activity study suggested that a hemiacetal hydroxyl functionality in the carbohydrate core and a biaryl bond of the 4,6-O-hexahydroxydiphenoyl (HHDP) group, which are components of ellagitannins including tellimagrandin I, are not necessary for the α-glucosidase inhibitory activity. Lastly, the antioxidant activity increased proportionally with the number of galloyl units.

Comparison of the Efficacy of Repaglinide Versus the Combination of Mitiglinide and Voglibose on Glycemic Variability in Japanese Patients with Type 2 Diabetes

BACKGROUND

Glycemic variability is a risk factor for total death and cardiovascular events. There are no obvious guidelines for the direct treatment of glycemic variability, but it can be improved with the treatment of postprandial hyperglycemia.

OBJECTIVE

We compared the effect of repaglinide versus the combination of mitiglinide and voglibose, used to improve postprandial hyperglycemia, on glycemic variability in Japanese patients with type 2 diabetes.

METHODS

We performed an open-label randomized cross-over trial between April 2016 and April 2018. Patients with type 2 diabetes who were admitted to our hospital were enrolled in our study (n = 12). Glycemic variability. was assessed using a continuous glucose monitoring system.

RESULTS

The average glucose level of the repaglinide phase (146.1 ± 20.7 mg/dl) and the combination of mitiglinide and voglibose phase (132.3 ± 19.8 mg/dl) were similar (P = 0.10). The standard division (P = 0.0005), coefficient of variation (P = 0.006), and mean amplitude of glycemic excursion (P = 0.002) of glucose were lower in the combination of mitiglinide and voglibose phase than in the repaglinide phase.

CONCLUSION

Treatment with the combination of mitiglinide and voglibose might be more effective than repaglinide for the improvement of glycemic variability.

High level of individual lipid profile and lipid ratio as a predictive marker of poor glycemic control in type-2 diabetes mellitus

Introduction: Diabetes is often accompanied by undiagnosed dyslipidemia. The aim of the study is to investigate the clinical relevance of lipid profiles and lipid ratios as predictive biochemical models for glycemic control in patients with type 2 diabetes mellitus (T2DM). Methods: This is a retrospective study recruiting 140 patients with T2DM during a one-year period, 2018-2019, at the Diabetic Center Sanglah General Hospital and Internal Medicine Polyclinic Puri Raharja General Hospital. Demographic characteristics, glycosylated hemoglobin (HBA1c) , and lipid profile were recorded and analyzed using SPSS version 25.0 for Windows. The sample is then classified into good (HBA1c≤7) and poor (HBA1c>7) glycemic control. Risk analysis model, receiver operator characteristics (ROC) analysis, and correlation test were used to evaluate the association of HBA1c level with lipid profile and lipid ratio parameters. Result: Lipid profile findings such as total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) , triglycerides (TG), and lipid ratio parameter (LDL-C to high-density lipoprotein cholesterol (HDL-C) ratio) were higher in patients in the poor glycemic control group (p<0.05) and HDL-C was significantly lower in patients with poor glycemic control (p=0.001). There is a significant positive correlation between LDL, total cholesterol, LDL-C, TG, and TC to HDL-C ratio, triglycerides, and TC/HDL-C ratio with HBA1c level. Meanwhile, a negative correlation was observed on HDL-C with the HBA1c level. Only TC/HDL-C ratio and LDL-C/HDL-C ratio parameters may be used as predictive models (AUC>0.7), with cutoff point, sensitivity, and specificity of 4.68 (77%; 52%) and 3.06 (98%; 56%) respectively. A risk analysis model shows that the LDL-C/HDL-C ratio parameter is the most influential risk factor in the occurrence of poor glycemic control (adjusted OR =38.76; 95% CI: 27.32-56.64; p<0.001). Conclusion: Lipid profiles (LDL-C) and lipid ratios (LDL-C/HDL-C and TC/HDL-C ratio) show potential markers that can be used in predicting glycemic control in patients with T2DM.

Comparison of Efficacy and Economic Value of Prandilin 25 and Humalog Mix 25 in Patients with Newly Diagnosed Type 2 Diabetes by a Continuous Glucose Monitoring System

INTRODUCTION

To determine the clinical efficacy and economic value of insulin lispro 25-Prandilin 25 vs. insulin lispro 25-Humalog mix 25 in treatment of newly diagnosed type 2 diabetes mellitus (T2DM) by a continuous glucose monitoring system (CGMS).

METHODS

This was a single-center, randomized, case-crossover clinical trial. Participants were randomly allocated to two groups and underwent two kinds of insulin lispro 25 treatment separated by a 1-day washout period. In total, 81 patients with newly diagnosed T2DM with hemoglobin A1c (HbA1c) above 9% were hospitalized and randomly divided to receive Prandilin 25/Humalog mix 25 or Humalog mix 25/Prandilin 25 treatment. All participants were subjected to metformin therapy simultaneously. Glycemic control was reached after 7-8 days Prandilin 25 or Humalog mix 25 treatment; each patient received continuous glucose monitoring (CGM) for 5 consecutive days (from day 1 to day 5). On day 3 of CGM performance, Prandilin 25 treatment was switched to Humalog mix 25 treatment at the same dosage or vice versa. Parameters representing glycemic variability (GV) and postprandial glucose excursions, including 24-h mean blood glucose (24hMBG), 24-h standard deviation of blood glucose (24hSDBG), 24-h mean amplitude of glycemic excursion (24hMAGE), large amplitude of glycemic excursion (LAGE), incremental area under the curve (AUC) for different glucose levels, and postmeal relative areas under the CGM curve (AUCpp) for 1-4 h of each meal, were calculated for each patient.

RESULTS

No significant differences were found in the 24hMAGE, 24hMBG, 24hSDBG, LAGE, mean 1-h preprandial blood glucose and the incidence of hypoglycemia between the Prandilin 25 treatment group and Humalog mix 25 treatment group. Similarly, there were no between-treatment differences for AUC and time when blood glucose was below 3.9 mmol/l, between 3.9 mmol/l and 10.0 mmol/l, or above 10.0 mmol/l. Further analysis showed the AUCpp for 1-4 h of each meal for two kinds of treatments were similar. However, the mean estimated cost of Prandilin 25 was only 85% of Humalog mix 25 in one treatment course.

CONCLUSION

Prandilin 25 is non-inferior in clinical efficacy compared with Humalog mix 25. In view of the significant difference in the cost of the two kinds of insulin lispro 25, Prandilin 25 is a much more cost-effective anti-diabetes drug for management of T2DM.

TRIAL REGISTRATION

Chinese Clinical Trial Register identifier, ChiCTR1800015829.

Glucose excursions and hypoglycemia in patients with type 2 diabetes treated with mitiglinide/voglibose versus glimepiride: A randomized cross-over trial

BACKGROUND

Glucose excursions and hypoglycemia are associated with cardiovascular complications. However, no studies have evaluated glucose excursions and the frequency of hypoglycemia in patients treated with mitiglinide/voglibose versus glimepiride as add-on to dipeptidyl peptidase-4 inhibitor therapy.

METHODS

This cross-over trial included 20 patients with type 2 diabetes. After initiating vildagliptin 100 mg, patients were randomly assigned to receive mitiglinide 10 mg/voglibose 0.2 mg three times daily for 3 days followed by glimepiride 1 mg once daily for the subsequent 3 days as add-on therapy, or vice versa. Glucose excursions and hypoglycemia frequency were measured using 24-h continuous glucose monitoring. Metabolic profile changes were evaluated using a meal tolerance test.

RESULTS

The mean glucose levels in the mitiglinide/voglibose and glimepiride phases were identical (8.01 vs 8.24 mmol/L, respectively). However, during the mitiglinide/voglibose phase compared with the glimepiride phase, the standard deviation of glucose (1.30 vs 2.10 mmol/L; P < 0.001), mean amplitude of glycemic excursions (3.47 vs 5.28 mmol/L; P < 0.001), M-value (24.6 vs 70.0; P < 0.001), continuous overlapping net glycemic action for a 1-h time interval (22.6 vs 31.0; P < 0.001), and area under the curve >10 mmol/L (0.18 vs 0.52 mmol/L per h; P < 0.001) were significantly lower. Hypoglycemia (glucose <3.8 mmol/L) was not observed during the mitiglinide/voglibose phase, but occurred 0.35 times/day in those taking glimepiride. Moreover, the mitiglinide/voglibose phase had higher premeal and lower post-meal glucose levels than the glimepiride phase.

CONCLUSIONS

Adding mitiglinide/voglibose to vildagliptin therapy results in more efficient postprandial glucose control and less hypoglycemia than adding glimepiride.

A study on the glycemic, lipid and blood pressure control among the type 2 diabetes patients of north Kerala, India

AIM

The aim of the study was to detect the level of comprehensive diabetes control among the diabetic patients of Kerala, India.

METHODS

Patients (1200) were randomly selected from a diabetes care center. Their blood sugar, biochemical and anthropometric measurements were done and statistically analyzed.

RESULTS

Only 28.3% had their HbA1c at or below 7% and 45% above 9%. One-third of the female and one-fifth of the male patients had coronary artery disease. The prevalence of hypertension was almost equal in both sexes. However, there was a statistically significant higher systolic blood pressure (mean 162.12mmHg vs 147.49mmHg, p=0.01044) among females. The total cholesterol was above 200mg/dl in 42.1% of males and 45.61% of females. The triglyceride was >150mg/dl in 38.6% males and 50.88% females. Low high density lipoprotein (HDL) cholesterol levels were found in 20.07% of males and 41.12% of females (p=0.0445). The mean low density lipoprotein (LDL) was 121.75 (±32.29) CONCLUSION: The mean blood sugar values are found to be high, which will lead to a predictable increase in vascular disease, which in turn will affect the quality of health and productivity of the individual and the economic growth of the society as a whole. Studies suggest that therapeutic interventions to improve glycemic control may reduce the risk of cardiovascular disease and microvascular disease. This study shows that the level of diabetes control in Kerala is unsatisfactory. We need more medications, better strategies and more emphasis on glycemic management than we are currently able to apply.

A study on the glycemic, lipid and blood pressure control of type 2 diabetes patients of Kerala

AIM

Aim of the study was to detect the level of comprehensive diabetes control among the diabetic patients of Kerala, India.

METHOD

Patients (1200) were randomly selected from a diabetes care center. Their blood sugar and other biochemical and anthropometric measurements were done and statistically analyzed.

RESULT

Only 28.3% had their A1C at or below 7% and 45% above 9%. 1/3rd of the female and 1/5th of the male patients had CAD. The prevalence of hypertension was almost equal in both sexes. However, there was a statistically significant higher systolic BP (mean 162.12mm Hg vs 147.49mm Hg, p=0.01044) among females. The total Cholesterol was above 200mg/dl in 42.1% of males and 45.61% of females. The triglyceride was >150mg/dl in 38.6% males and 50.88% females. Low HDL cholesterol levels were found in 20.07% of males and 41.12% of females (p=0.0445). The mean LDL was 121.75 (±32.29247) DISCUSSION: The mean blood sugar values are found to be high which will lead to a predictable increase in vascular disease, which in turn will affect the quality of health and productivity of the individual and the economic growth of the society as a whole. Studies suggest that therapeutic interventions to improve glycemic control may reduce the risk of CVD and microvascular disease.

CONCLUSION

This study shows that the level of diabetes control in Kerala is unsatisfactory. We need more medications, better strategies, and more emphasis on glycemic management than we are currently able to apply.

The vasorelaxant effect of mitiglinide via activation of voltage-dependent K+ channels and SERCA pump in aortic smooth muscle

AIMS

The vasorelaxant effects of the anti-diabetic drug, mitiglinide in phenylephrine (Phe)-pre-contracted aortic rings were examined.

MATERIALS AND METHODS

Arterial tone measurement was performed in aortic smooth muscle cells.

KEY FINDINGS

Mitiglinide dose-dependently induced vasorelaxation. Application of the large-conductance Ca²⁺-activated K⁺ (BK_Ca) channel blocker paxilline, inwardly rectifying K⁺ (Kir) channel blocker Ba²⁺, and ATP-sensitive K⁺ (K_ATP) channel blocker glibenclamide did not affect the vasorelaxant effect of mitiglinide. However, application of the voltage-dependent K⁺ (Kv) channel blocker 4-AP, effectively inhibited mitiglinide-induced vasorelaxation. Although pretreatment with the Ca²⁺ channel blocker nifedipine did not alter the mitiglinide-induced vasorelaxation, pretreatment with the sarcoplasmic/endoplasmic reticulum Ca²⁺-ATPase (SERCA) pump inhibitor thapsigargin and cyclopiazonic acid reduced the vasorelaxant effect of mitiglinide. In addition, the vasorelaxant effect of mitiglinide was not affected by the inhibitors of adenylyl cyclase, protein kinase A, guanylyl cyclase, or protein kinase G. Elimination of the endothelium and inhibition of endothelium-dependent vasorelaxant mechanisms also did not change the vasorelaxant effect of mitiglinide.

SIGNIFICANCE

We proposed that mitiglinide induces vasorelaxation via activation of Kv channels and SERCA pump. However, the vasorelaxant effects of mitiglinide did not involve other K⁺ channels, Ca²⁺ channels, PKA/PKG signaling pathways, or the endothelium.

Effect of Acarbose on Glycemic Variability in Patients with Poorly Controlled Type 2 Diabetes Mellitus Receiving Stable Background Therapy: A Placebo-Controlled Trial

STUDY OBJECTIVE

To evaluate the effect of acarbose on glycemic control and glycemic variability, using a continuous glucose-monitoring system, in patients with type 2 diabetes mellitus who were not well controlled on metformin and vildagliptin therapy.

DESIGN

Multicenter, randomized, double-blind, placebo-controlled study.

SETTING

Clinical research units at three hospitals in Italy.

PATIENTS

Fifty-three patients with type 2 diabetes who were taking stable dosages of metformin 850 mg 3 times/day and vildagliptin 50 mg twice/day for at least 3 months and who were not adequately controlled with these therapies.

INTERVENTION

Patients were randomized to either placebo or acarbose 100 mg 3 times/day to be added to their metformin-vildagliptin regimen.

MEASUREMENTS AND MAIN RESULTS

Glycemic excursions were assessed by using a continuous glucose-monitoring system for 1 week. Glycemic control was estimated as the mean blood glucose (MBG) level, the area under the glucose concentration-time curve for a glucose level above 70 mg/dl (AUC above 70) or 180 mg/dl (AUC above 180), and the percentage of time that the glucose level was above 70 mg/dl (T above 70) or 180 mg/dl (T above 180). Intraday glycemic variability was assessed by the standard deviation of the blood glucose level, the mean amplitude of glycemic excursions (MAGE), the M value, and continuous overlapping net glycemic action. Day-to-day glycemic variability was assessed as the mean of daily difference (MODD). The MBG level was ~20 mg/dl lower in the acarbose group than in the placebo group (p<0.05), particularly during the postprandial period. The AUC above 70 did not significantly differ between the two groups, whereas the AUC above 180 was ~40% lower in the acarbose group than in the placebo group during the daytime (p<0.01). The T above 180 was significantly higher in the placebo group than in the acarbose group (31% vs 8%, p<0.01. Moreover, the standard deviation and MAGE values were significantly lower in the acarbose group. The MODD value was not significantly changed in either group, and no significant differences were recorded between groups. All adverse events were mild in both groups, with only a significantly greater frequency of flatulence noted in the acarbose group (5% with acarbose vs 0.5% with placebo, p<0.05).

CONCLUSION

The addition of acarbose to metformin and vildagliptin background therapy in patients with inadequately controlled type 2 diabetes decreased intraday glycemic variability, especially postprandial variability, but it was not associated with a significant change in interday glycemic variability.

Clinical pharmacokinetics and pharmacodynamics of the novel SGLT2 inhibitor ipragliflozin

Ipragliflozin (Suglat(®)) is a potent and selective inhibitor of sodium-glucose cotransporter-2 that was recently launched in Japan. Its mechanism of action involves the suppression of glucose re-absorption in the kidney proximal tubules, causing excretion of glucose in the urine. The aim of this review is to provide a comprehensive overview of currently available pharmacokinetic and pharmacodynamic data on ipragliflozin, including studies in healthy subjects, patients with type 2 diabetes mellitus and special populations. In single- and multiple-dose studies, the maximum plasma concentration and area under the plasma concentration-time curve (AUC) for ipragliflozin increased in a dose-dependent manner. Although urinary excretion of ipragliflozin is low (approximately 1 %), tubular concentration of free ipragliflozin is adequate to provide pharmacological activities. No clinically relevant effects of age, gender or food on the exposure of ipragliflozin were observed. The AUC for ipragliflozin was 20-30 % greater in patients with moderate renal or hepatic impairment than in patients with normal renal or hepatic function. In drug-drug interaction studies, the pharmacokinetics of ipragliflozin and other oral antidiabetic drugs (metformin, sitagliptin, pioglitazone, glimepiride, miglitol and mitiglinide) were not significantly affected by their co-administration. Urinary glucose excretion (UGE) also increased in a dose-dependent manner, approaching a maximum effect at 50-100 mg dosages in Japanese healthy volunteers and patients with type 2 diabetes. The change in UGE from baseline (ΔUGE) tended to be lower in older subjects and female subjects, compared with younger subjects and male subjects, respectively. ΔUGE tended to decrease with decreasing renal function, especially in patients with type 2 diabetes with moderate or severe renal impairment.

Ginkgolide A reduces inflammatory response in high-glucose-stimulated human umbilical vein endothelial cells through STAT3-mediated pathway

High-glucose-induced low-grade inflammation has been regarded as a key event in the onset and progression of endothelial dysfunction in diabetic vascular complications. Ginkgolide A (GA), a major compound from Ginkgo biloba extract, is widely used for the treatment of cardiovascular diseases and diabetic vascular complications. Here, its effect on high-glucose-stimulated vascular inflammation in human umbilical vein endothelial cells (HUVECs) was investigated. In the present study, the optimal stimulation conditions for HUVECs were screened for inducing endothelial inflammation, namely, high glucose at the concentration of 30mM for continuous 8h. The endothelial production of high-glucose-induced interleukin (IL)-4, IL-6, IL-13 and signal transducer and activator of transcription-3 (STAT-3) phosphorylation were significantly inhibited by the pretreatment with GA at concentrations of 10, 15 and 20μM based on enzyme-linked immunosorbent assay (ELISA), western blot or/and RT-PCR experiments. These senescent alterations induced by high glucose were significantly attenuated by the specific STAT3 inhibitor S3I-201 at the concentration of 20μM. Furthermore, the phosphorylation of STAT3, IL-4, IL-6, IL-13 and intercellular cell adhesion molecule-1 (ICAM-1) protein as well as mRNA levels were attenuated by the pretreatment of cells with STAT3 siRNA. Our results demonstrated that GA improved high-glucose-caused low-grade vascular inflammation, which might be achieved through regulating the STAT3-mediated pathway. These findings indicated that GA might be a promising candidate for attenuating vascular inflammation in diabetic vascular complications.

Pharmacogenomics of glinides

Glinides, including repaglinide, nateglinide and mitiglinide, are a type of fasting insulin secretagogue that could help to mimic early-phase insulin release, thus providing improved control of the postprandial glucose levels. Glinides stimulate insulin secretion by inhibiting ATP-sensitive potassium channels in the pancreatic β-cell membrane. Although glinides have been widely used clinically and display excellent safety and efficacy, the response to glinides varies among individuals, which is partially due to genetic factors involved in drug absorption, distribution, metabolism and targeting. Several pharmacogenomic studies have demonstrated that variants of genes involved in the pharmacokinetics or pharmacodynamics of glinides are associated with the drug response. Polymorphisms of genes involved in drug metabolism, such as CYP2C9, CYP2C8 and SLCO1B1, may influence the efficacy of glinides and the incidence of adverse effects. In addition, Type 2 diabetes mellitus susceptibility genes, such as KCNQ1, PAX4 and BETA2, also influence the efficacy of glinides. In this article, we review and discuss current pharmacogenomics researches on glinides, and hopefully provide useful data and proof for clinical application.

Atherogenic, fibrotic and glucose utilising actions of glucokinase activators on vascular endothelium and smooth muscle

Background

Pharmaceutical interventions for diabetes aim to control glycaemia and to prevent the development of complications, such as cardiovascular diseases. Some anti-hyperglycaemic drugs have been found to have adverse cardiovascular effects in their own right, limiting their therapeutic role. Glucokinase activity in the pancreas is critical in enhancing insulin release in response to hyperglycaemia. Glucokinase activators (GKAs) are novel agents for diabetes which act by enhancing the formation of glucose-6-phosphate leading to increased insulin production and subsequent suppression of blood glucose. Little, however, is known about the direct effects of GKAs on cardiovascular cells.

Methods

The effect of the GKAs RO28-1675 and Compound A on glucose utilisation in bovine aortic endothelial cells (BAEC) and rat MIN6 was observed by culturing the cells at high and low glucose concentration in the presence and absence of the GKAs and measuring glucose consumption. The effect of RO28-1675 at various concentrations on glucose-dependent signalling in BAEC was observed by measuring Smad2 phosphorylation by Western blotting. The effect of RO28-1675 on TGF-β stimulated proteoglycan synthesis was measured by ³⁵S-SO₄ incorporation and assessment of proteoglycan size by SDS-PAGE. The effects of RO28-1675 on TGF-β mediated Smad2C phosphorylation in BAEC was observed by measurement of pSmad2C levels. The direct actions of RO28-1675 on vascular reactivity were observed by measuring arteriole tone and lumen diameter.

Results

GKAs were demonstrated to increase glucose utilisation in pancreatic but not endothelial cells. Glucose-activated Smad2 phosphorylation was decreased in a dose-dependent fashion in the presence of RO28-1675. No effect of RO28-1675 was observed on TGF-β stimulated proteoglycan production. RO28-1675 caused a modest dilation in arteriole but not contractile sensitivity.

Conclusions

GKA RO28-1675 did not increase glucose consumption in endothelial cells indicating the absence of glucokinase in those cells. No direct deleterious actions, in terms of atherogenic changes or excessive vasoactive effects were seen on cells or vessels of the cardiovascular system in response to GKAs. If reflected in vivo, these drugs are unlikely to have their use compromised by direct cardiovascular toxicity.

The proinsulin/insulin (PI/I) ratio is reduced by postprandial targeting therapy in type 2 diabetes mellitus: a small-scale clinical study

Background

An elevated PI/I ratio is attributable to increased secretory demand on β-cells. However, the effect of postprandial targeting therapy on proinsulin level is unknown. We evaluated the metabolic effect of glinide and sulfonylurea (SU) using the meal tolerance test (MTT).

Methods

MTT was applied to previously untreated Type 2 Diabetes Mellitus (T2DM) subjects. Twenty-two participants were given a test meal (450 kcal). Plasma glucose and insulin were measured at 0 (fasting), 30, 60, 120, and 180 min. Serum proinsulin and C-peptide immunoreactivity (CPR) were measured at 0 and 120 min. Postprandial profile was assessed at baseline and following 3 months treatment with either mitiglinide or glimepiride.

Results

Plasma glucose level at 30, 60, 120, and 180 min was significantly improved by mitiglinide. Whereas, glimepiride showed a significant improve plasma glucose at 0, 180 min. Peak IRI shifted from 120 to 30 min by mitiglinide treatment. The pattern of insulin secretion was not changed by glimepiride treatment. Whereas mitiglinide did not affect the PI/I ratio, glimepiride tended to increase the PI/I ratio. Moreover, although mitiglinide did not affect PI/I ratio as a whole, marked reduction was noted in some patients treated by mitiglinide. PI/I ratio was reduced significantly in the responder group. The responder subgroup exhibited less insulin resistance and higher insulinogenic index at baseline than non-responders. Moreover, the triglyceride level of responders was significantly lower than that of non-responders.

Conclusions

Mitiglinide improved postprandial insulin secretion pattern and thereby suppressed postprandial glucose spike. In T2DM patients with low insulin resistance and low triglyceride, mitiglinide recovered impaired β-cell function from the viewpoint of the PI/I ratio.

Trial registration

UMIN-CTR: UMIN000010467

Methylglyoxal modulates endothelial nitric oxide synthase-associated functions in EA.hy926 endothelial cells

BACKGROUND

Increased levels of the sugar metabolite methylglyoxal (MG) in vivo were shown to participate in the pathophysiology of vascular complications in diabetes. Alterations of endothelial nitric oxide synthase (eNOS) activity by hypophosphorylation of the enzyme and enhanced monomerization are found in the diabetic milieu, and the regulation of this still remains undefined. Using various pharmacological approaches, we elucidate putative mechanisms by which MG modulates eNOS-associated functions of MG-stimulated superoxide O₂•⁻ production, phosphorylation status and eNOS uncoupling in EA.hy926 human endothelial cells.

METHODS

In cultured EA.hy926 endothelial cells, the effects of MG treatment, tetrahydrobiopterin (BH4; 100 μM) and sepiapterin (20 μM) supplementation, NOS inhibition by N(G)-nitro-L-arginine methyl ester (L-NAME; 50 μM), and inhibition of peroxynitrite (ONOO⁻) formation (300 μM Tempol plus 50 μM L-NAME) on eNOS dimer/monomer ratios, Ser-1177 eNOS phosphorylation and 3-nitrotyrosine (3NT) abundance were quantified using immunoblotting. O₂•⁻-dependent fluorescence was determined using a commercially available kit and tissue biopterin levels were measured by fluorometric HPLC analysis.

RESULTS

In EA.hy926 cells, MG treatment significantly enhanced O₂•⁻ generation and 3NT expression and reduced Ser-1177 eNOS phosphorylation, eNOS dimer/monomer ratio and cellular biopterin levels indicative of eNOS uncoupling. These effects were significantly mitigated by administration of BH4, sepiapterin and suppression of ONOO⁻ formation. L-NAME treatment significantly blunted eNOS-derived O₂•⁻ generation but did not modify eNOS phosphorylation or monomerization.

CONCLUSION

MG triggers eNOS uncoupling and hypophosphorylation in EA.hy926 endothelial cells associated with O₂•⁻ generation and biopterin depletion. The observed effects of the glycolysis metabolite MG presumably account, at least in part, for endothelial dysfunction in diabetes.

Effects of combination therapy with mitiglinide and voglibose on postprandial plasma glucose in patients with type 2 diabetes mellitus

Patients with diabetes mellitus are at increased risk from cardiovascular-related morbidity and mortality as compared with healthy individuals. An association between the postprandial metabolic state and atherogenesis has been observed in patients with diabetes mellitus. In the Study to Prevent Non-Insulin-Dependent Diabetes Mellitus (STOP-NIDDM), treatment with an α-glucosidase inhibitor (α-GI) in patients with impaired glucose tolerance not only reduced the rate of conversion from impaired glucose tolerance to type 2 diabetes mellitus (T2DM), but was also associated with a reduction in the risk of cardiovascular events. These results suggested the importance of treating postprandial hyperglycemia in the early stages of T2DM. Glinides are rapid and short-acting insulin secretagogues that bind to the sulfonylurea receptors on pancreatic β-cells to facilitate rapid insulin secretion, restore postprandial early insulin secretion, and reduce the postprandial glucose spike. Moreover, α-GIs reduce postprandial hyperglycemia and insulin secretion by delaying the digestion of carbohydrates and polysaccharides in the small intestine. Then, both glinides and α-GI have beneficial effects for treating patients with T2DM and impaired glucose tolerance. Considering the ameliorating effects of these drugs on postprandial metabolic disorders, combinations of glinides and α-GI might constitute a promising therapeutic strategy for managing patients with T2DM, and also appear to be suitable for Japanese people, who consume more carbohydrates, such as polished rice, than Caucasians. It has recently been reported that combined use of mitiglinide and voglibose reduces postprandial insulin secretion and blunts diurnal glycemic changes in T2DM patients. This therapy can thus be regarded as being suitable for achieving strict postprandial glycemic control. In this report, we outline the effects of this combination therapy on postprandial plasma glucose and assess its safety.

Miglitol improves postprandial endothelial dysfunction in patients with acute coronary syndrome and new-onset postprandial hyperglycemia

BACKGROUND

Hyperglycemia, a risk factor for development of cardiovascular disease, causes endothelial dysfunction. Alpha-glucosidase inhibitors (α-GIs) improve postprandial hyperglycemia (PPHG) and may have favorable effects on associated cardiovascular disease. Effects of α-GIs in patients with acute coronary syndrome (ACS) and PPHG remain unclear; thus, we assessed the effect of α-GI miglitol on endothelial function in such patients by digital reactive hyperemia peripheral arterial tonometry (RH-PAT).

METHODS

Fifty-four patients with ACS who underwent primary percutaneous coronary intervention were enrolled in the study: 36 with new-onset PPHG and 18 with normal glucose tolerance. Eighteen PPHG patients were given 50 mg of miglitol with each meal for 1 week. Endothelial function was assessed on the basis of the RH-PAT index (RHI) before and after the 1-week miglitol treatment. The other 18 PPHG patients and the 18 NGT patients were not given any anti-diabetic agent for 1 week, and endothelial function was assessed.

RESULTS

Postprandial RHI decreased significantly in patients with PPHG. Miglitol improved PPHG significantly; postprandial RHI also improved (p = 0.007). Significant inverse correlation was found between the postprandial change in RHI and postprandial fasting-to-60-minutes surge in glucose (r = -0.382, p = 0.009). Moreover, the improvement in endothelial function correlated with the reduced postprandial glucose surge achieved with miglitol (r = -0.462, p = 0.001).

CONCLUSIONS

Postprandial changes in glucose are related to endothelial dysfunction in ACS. Miglitol-based improvement in PPHG appears to improve endothelial function. The effect of miglitol on glucose-dependent endothelial function might improve outcomes of ACS.

Glycemic variability is associated with subclinical atherosclerosis in Chinese type 2 diabetic patients

Background

The contribution of glycemic variability to macrovascular complications remains unclear. We therefore investigated the association between glycemic variability and cervical and/or intracranial atherosclerosis in Chinese type 2 diabetic patients.

Methods

We conducted a cross-sectional study in 216 type 2 diabetic patients with a hemoglobin A_1c of 8.3 ± 1.7% and a median diabetes duration of 9.0 years. The standard deviation of blood glucose values (SDBG) and the mean amplitude of glycemic excursion (MAGE) were calculated from continuous glucose monitoring system data for assessing glycemic variability while 24h mean blood glucose (MBG) was calculated for measuring overall blood glucose level. Magnetic resonance angiography (MRA) was used to detect cervical and/or intracranial plaque, and ultrasonography was used to quantify carotid intima-media thickness (IMT) as an index of subclinical atherosclerosis.

Results

One hundred and fifty-three patients (70.8%) presented with cervical and/or intracranial lesions on MRA among 216 patients in the study. Elder age, increased systolic blood pressure, increased MBG and elevated low density lipoprotein cholesterol were independent contributors to plaque formation. In patients without stenosis (n = 63), SDBG (r = 0.412, P = 0.001) and MAGE (r = 0.365, P = 0.005) were both correlated with carotid IMT and these relationships remained significant in multiple linear regression analysis (multiple R² = 0.314 for the model including SDBG and multiple R² = 0.268 for the model including MAGE). However, SDBG and MAGE were not significantly different among patients with different stenosis degrees.

Conclusions

Glycemic variability is associated with subclinical atherosclerosis in Chinese type 2 diabetic patients.

The effects of postprandial glucose and insulin levels on postprandial endothelial function in subjects with normal glucose tolerance

BACKGROUND

Previous studies have demonstrated that postprandial hyperglycemia attenuates brachial artery flow-mediated dilation (FMD) in prediabetic patients, in diabetic patients, and even in normal subjects. We have previously reported that postprandial hyperinsulinemia also attenuates FMD. In the present study we evaluated the relationship between different degrees of postprandial attenuation of FMD induced by postprandial hyperglycemia and hyperinsulinemia and differences in ingested carbohydrate content in non-diabetic individuals.

METHODS

Thirty-seven healthy subjects with no family history of diabetes were divided into 3 groups: a 75-g oral glucose loading group (OG group) (n = 14), a test meal group (TM group) (n = 12; 400 kcal, carbohydrate content 40.7 g), and a control group (n = 11). The FMD was measured at preload (FMD0) and at 60 minutes (FMD60) and 120 (FMD120) minutes after loading. Plasma glucose (PG) and immunoreactive insulin (IRI) levels were determined at preload (PG0, IRI0) and at 30 (PG30, IRI30), 60 (PG60, IRI60), and 120 (PG120, IRI120) minutes after loading.

RESULT

Percentage decreases from FMD0 to FMD60 were significantly greater in the TM group (-21.19% ± 17.90%; P < 0.001) and the OG group (-17.59% ± 26.64%) than in the control group (6.46% ± 9.17%; P < 0.01), whereas no significant difference was observed between the TM and OG groups. In contrast, the percentage decrease from FMD0 to FMD120 was significantly greater in the OG group (-18.91% ± 16.58%) than in the control group (6.78% ± 11.43%; P < 0.001) or the TM group (5.22% ± 37.22%; P < 0.05), but no significant difference was observed between the control and TM groups. The FMD60 was significantly correlated with HOMA-IR (r = -0.389; P < 0.05). In contrast, FMD120 was significantly correlated with IRI60 (r = -0.462; P < 0.05) and the AUC of IRI (r = -0.468; P < 0.05). Furthermore, the percentage change from FMD0 to FMD120 was significantly correlated with the CV of PG (r = 0.404; P < 0.05), IRI60 (r = 0.401; p < 0.05) and the AUC of IRI (r = 0.427; P < 0.05). No significant correlation was observed between any other FMDs and glucose metabolic variables.

CONCLUSION

Differences in the attenuation of postprandial FMD induced by different postprandial insulin levels may occur a long time postprandially but not shortly after a meal.