Beneficial effects of nateglinide on insulin resistance in type 2 diabetes

Evaluation of the effect of MTNR1B rs10830963 gene variant on the therapeutic efficacy of nateglinide in treating type 2 diabetes among Chinese Han patients

Genetic polymorphisms in the MTNR1B gene is associated with type 2 diabetes mellitus (T2DM); however, there is no evidence about its impact on the therapeutic efficacy of nateglinide. This prospective case-control study was designed to investigate the effect of MTNR1B rs10830963 gene variant on the therapeutic efficacy of nateglinide in treating T2DM. We genotyped untreated T2DM patients (N = 200) and healthy controls (N = 200) using the method of the high resolution of melting curve (HRM). Newly diagnosed T2DM patients (n = 60) with CYP2C9*1 and SLCO1B1 521TT genotypes were enrolled and given oral nateglinide (360 mg/d) for 8 weeks. The outcome was measured by collecting the venous blood samples before and at the 8th week of the treatment. The risk G allelic frequency of MTNR1B rs10830963 was higher in T2DM patients than the healthy subjects (P < 0.05). Post 8-week of treatment, newly diagnosed T2DM patients showed a less reduction in fasting plasma glucose levels and less increase in the carriers of genotype CG + GG at rs10830963 when compared with the CC genotype (P < 0.05). MTNR1B rs10830963 polymorphism was associated with the therapeutic efficacy of nateglinide in T2DM patients. Also, the CC homozygotes had a better effect than G allele carriers.Trial registration Chinese Clinical Trial Register ChiCTR13003536, date of registration: May 14, 2013.

Mechanisms and Characteristics of Sulfonylureas and Glinides

BACKGROUND

Type 2 diabetes mellitus is a complex progressive endocrine disease characterized by hyperglycemia and life-threatening complications. It is the most common disorder of pancreatic cell function that causes insulin deficiency. Sulfonylurea is a class of oral hypoglycemic drugs. Over the past half century, these drugs, together with the subsequent non-sulfonylureas (glinides), have been the main oral drugs for insulin secretion.

OBJECTIVE

Through in-depth study, the medical profession considers it as an important drug for improving blood sugar control.

METHODS

The mechanism, characteristics, efficacy and side effects of sulfonylureas and glinides were reviewed in detail.

RESULTS

Sulfonylureas and glinides not only stimulated the release of insulin from pancreatic cells, but also had many extrapanular hypoglycemic effect, such as reducing the clearance rate of insulin in liver, reducing the secretion of glucagon, and enhancing the sensitivity of peripheral tissues to insulin in type 2 diabetes mellitus.

CONCLUSION

Sulfonylureas and glinides are effective first-line drugs for the treatment of diabetes mellitus. Although they have the risk of hypoglycemia, weight gain and cardiovascular disease, their clinical practicability and safety can be guaranteed as long as they are reasonably used.

Predictive factors of posttransplant glucose intolerance in Japanese patients with type 1 diabetes after pancreas transplantation

Pancreas transplantation (PTx) has been performed worldwide for patients with type 1 diabetes accompanied with end-stage renal disease or uncontrollable glycemic fluctuation. Nevertheless, risk factors of posttransplant glucose intolerance, which is responsible for progress of diabetic complications, remains unclear, especially in cases without pancreatic graft function loss. Therefore, this study was conducted to search for predictive factors of future glucose tolerance in PTx recipients without pancreatic graft function loss. Subjects were selected from among 41 Japanese patients with type 1 diabetes who received PTx between 2000 and 2016 in Osaka University Hospital, and 24 subjects free from rejections and thromboses were analyzed. Several examinations to evaluate insulin secretion and insulin sensitivity within 6 months after transplantation (initial examination) were performed. Glucose tolerance was evaluated by 120-minute post-load plasma glucose level during 75-g oral glucose tolerance tests (OGTT), referred to as PG_OGTT120, at the initial examination and between 1 year and 2 years posttransplantation (maintenance period). The initial examination factors that were correlated with PG_OGTT120 in the maintenance period were PG_OGTT120 [r = 0.52 (p = 0.01)], insulinogenic index [r = -0.65 (p < 0.01)], and the ratio of incremental area under the curve of insulin to that of plasma glucose (iAUCR) calculated from data of OGTT [r = -0.65 (p < 0.01)]. Insulinogenic index [β = -0.28 (p = 0.02)] and iAUCR [β = -0.29 (p = 0.02)] were still significantly correlated with PG_OGTT120 in the maintenance period after adjustment for PG_OGTT120 at the initial examination. In conclusion, insulinogenic index and iAUCR from OGTT performed in the early posttransplantation period were predictive factors of future glucose intolerance.

Role of LAP+CD4+ T cells in the tumor microenvironment of colorectal cancer

AIM

To investigate the abundance and potential functions of LAP⁺CD4⁺ T cells in colorectal cancer (CRC).

METHODS

Proportions of LAP⁺CD4⁺ T cells were examined in peripheral blood and tumor/paratumor tissues of CRC patients and healthy controls using flow cytometry. Expression of phenotypic markers such as forkhead box (Fox)p3, cytotoxic T-lymphocyte-associated protein (CTLA)-4, chemokine CC receptor (CCR)4 and CCR5 was measured using flow cytometry. LAP^-CD4⁺ and LAP⁺CD4⁺ T cells were isolated using a magnetic cell-sorting system and cell purity was analyzed by flow cytometry. Real-time quantitative polymerase chain reaction was used to measure expression of cytokines interleukin (IL)-10 and transforming growth factor (TGF)-β.

RESULTS

The proportion of LAP⁺CD4⁺ T cells was significantly higher in peripheral blood from patients (9.44% ± 3.18%) than healthy controls (1.49% ± 1.00%, P < 0.001). Among patients, the proportion of LAP⁺CD4⁺ T cells was significantly higher in tumor tissues (11.76% ± 3.74%) compared with paratumor tissues (3.87% ± 1.64%, P < 0.001). We also observed positive correlations between the proportion of LAP⁺CD4⁺ T cells and TNM stage (P < 0.001), distant metastasis (P < 0.001) and serum level of carcinoembryonic antigen (P < 0.05). Magnetic-activated cell sorting gave an overall enrichment of LAP⁺CD4⁺ T cells (95.02% ± 2.87%), which was similar for LAP^-CD4⁺ T cells (94.75% ± 2.76%). In contrast to LAP^-CD4⁺ T cells, LAP⁺CD4⁺ T cells showed lower Foxp3 expression but significantly higher levels of CTLA-4, CCR4 and CCR5 (P < 0.01). LAP⁺CD4⁺ T cells expressed significantly larger amounts of IL-10 and TGF-β but lower levels of IL-2, IL-4, IL-17 and interferon-γ, compared with LAP^-CD4⁺ T cells.

CONCLUSION

LAP⁺CD4⁺ T cells accumulated in the tumor microenvironment of CRC patients and were involved in immune evasion mediated by IL-10 and TGF-β.

Safety and efficacy of acarbose in the treatment of diabetes in Chinese patients

Acarbose is an α-glucosidase inhibitor that is commonly used to control postprandial blood glucose. It functions as a competitive and reversible inhibitor of small intestinal brush border glucosidase, blocks the degradation of starch and sucrose, and delays the absorption of glucose and fructose in the alimentary tract. The starch content of a diet might alter the hypoglycemic effects of acarbose because of its mechanism of action. Chinese individuals consume a typical Eastern diet, which is characterized by a high intake of whole grains, legumes, vegetables, fruits, and fish. These dietary habits allow acarbose to be used extensively in the People’s Republic of China. Several Chinese-based studies have demonstrated that the use of acarbose as a monotherapy had similar effects on other anti-diabetes agents in decreasing glycosylated hemoglobin (HbA_1c) and blood glucose levels, and acarbose in combination with other anti-diabetic drugs could further reduce blood glucose and decrease the mean amplitude of glycemic excursions. Importantly, acarbose is safe and well tolerated, with a low incidence of adverse effects. This article provides a comprehensive review of the safety and efficacy of acarbose for the treatment of diabetes in Chinese patients.

Effects of nateglinide and acarbose on glycemic excursions in standardized carbohydrate and mixed-meal tests in drug-naïve type 2 diabetic patients

The aim of this study was to compare the effects of nateglinide and acarbose on glycemic excursions and postprandial glucose profiles with different types of meals (standardized carbohydrate and mixed meals) in drug-naïve type 2 diabetic patients. A randomized, parallel-group prospective design clinical trial was conducted and a total of 39 drug-naïve patients (16 males and 23 females, aged 56.7±10.2 years) were enrolled. The patients were randomly divided into group A [nateglinide 120 mg three times daily (t.i.d.), n=19] and group B (acarbose 50 mg t.i.d., n=20). The standardized carbohydrate and mixed-meal tests were performed at baseline and at the end of study. Continuous glucose monitoring system (CGMS) data were recorded. Various parameters that measure glucose variability were derived from the CGMS data. In the standardized carbohydrate meal tests, the postprandial glucose excursions (PPGEs) were significantly decreased in the two groups after 12 weeks of treatment (P<0.05), whereas the decrease was more prominent in the acarbose compared to the nateglinide group (P=0.138). In the mixed-meal tests, the mean sensor glucose values [24-h mean blood glucose (MBG)] were significantly decreased in the two groups after 12 weeks of treatment (P<0.05) and the parameters of glucose excursions, including standardized deviation (SD), largest amplitude of glycemic excursion (LAGE), mean of daily differences (MODD) and mean amplitude of glycemic excursion (MAGE), were reduced in the two groups. However, the decreases in SD and LAGE in the nateglinide group were statistically significant, whereas in the acarbose group only the decreases in LAGE were statistically significant. The efficiency of nateglinide or acarbose in lowering postprandial 120-min hyperglycemia were similar in the standardized carbohydrate meal test. However, acarbose was more efficient in lowering postprandial 30- and 60-min hyperglycemia (P<0.05) compared to nateglinide. The fasting and postprandial total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) had a tendency to decrease from the baseline after 12 weeks of treatment with nateglinide, whereas fasting and postprandial high-density lipoprotein cholesterol (HDL-C) had a tendency to increase. Acarbose did not affect the fasting or postprandial lipid profiles after 12 weeks of treatment (P>0.05). In conclusion, nateglinide and acarbose effectively improved postprandial glycemic control, although acarbose was shown to be more efficient in controlling early (30 and 60 min) postprandial glucose excursions in the carbohydrate meal test, whereas nateglinide was shown to be superior to acarbose in controlling postprandial glucose excursions in the mixed-meal test.

Nateglinide and acarbose are comparably effective reducers of postprandial glycemic excursions in chinese antihyperglycemic agent-naive subjects with type 2 diabetes

BACKGROUND

Recent studies have identified postprandial glycemic excursions as risk factors for diabetes complications. This study aimed to compare the effects of nateglinide and acarbose treatments on postprandial glycemic excursions in Chinese subjects with type 2 diabetes.

SUBJECTS AND METHODS

This was a multicenter, open-label, randomized, active-controlled, parallel-group study. One hundred three antihyperglycemic agent-naive subjects with type 2 diabetes (hemoglobin A1c range, 6.5-9.0%) were prospectively recruited from four hospitals in China. The intervention was nateglinide (120 mg three times a day) or acarbose (50 mg three times a day) therapy for 2 weeks. A continuous glucose monitoring system was used to calculate the incremental area under the curve of postprandial blood glucose (AUCpp), the incremental glucose peak (IGP), mean amplitude of glycemic excursions, SD of blood glucose, the mean of daily differences, and 24-h mean blood glucose (MBG). Subjects' serum glycated albumin and the plasma insulin levels were also analyzed.

RESULTS

Both agents caused significant reductions on AUCpp and IGP. Similarly, both treatment groups showed significant improvements in the intra- and interday glycemic excursions, as well as the 24-h MBG and serum glycated albumin compared with baseline (P<0.001). However, neither of the agents produced a significantly better effect (P>0.05). Moreover, the nateglinide-treated group had significantly increased insulin levels at 30 min and at 120 min after a standard meal compared with baseline, whereas the acarbose-treated group decreased. No serious adverse events occurred in either group. The rates of hypoglycemic episodes were comparable in the two groups, and no severe hypoglycemic episode occurred in either group.

CONCLUSIONS

Nateglinide and acarbose were comparably effective in reducing postprandial glycemic excursions in antihyperglycemic agent-naive Chinese patients with type 2 diabetes, possibly through different pathophysiological mechanisms.

Nateglinide and acarbose for postprandial glucose control after optimizing fasting glucose with insulin glargine in patients with type 2 diabetes

AIMS

Basal insulin treatment is frequently used in type 2 diabetes, but the successful control of postprandial glucose is challenging. We compared the effect of preferential postprandial glucose targeting drugs for postprandial glucose control after optimizing fasting glucose with basal insulin.

METHODS

This study was performed in 58, insulin naïve type 2 diabetes. After fasting glucose was optimized by insulin glargine, nateglinide or acarbose was initiated and then crossed over after second wash out period. 75 g oral glucose tolerance test and 7 point self monitoring blood glucose for 3 days at the end of each period was performed.

RESULTS

Both drugs effectively reduced postprandial glucose levels compared with the insulin glargine monotherapy. No significant differences were found between nateglinide and acarbose in terms of mean glucose level, standard deviation of glucose levels, mean average glucose excursion and average daily risk range. Homeostasis model analysis (HOMA)% β, corrected insulin response and insulin-to-glucose ratio were significantly higher in the responder group compared with the non-responder. There was no episode of severe hypoglycemia.

CONCLUSIONS

Nateglinide and acarbose are equally effective in type 2 diabetes for postprandial glucose excursions during basal insulin treatment. The markers of beta cell function might be used for predicting response. (Clinical trial reg. no. NCT 00437918, clinicaltrial.gov.).

What is artificial endocrine pancreas? Mechanism and history

The artificial endocrine pancreas is a feedback control instrument that regulates insulin delivery on a minute-by-minute basis according to measured blood glucose levels. Only one type of bedside-type artificial endocrine pancreas is now available in Japan: STG-22 (Nikkiso Co. Ltd., Japan). In the insulin infusion algorithm, insulin is infused on the basis of its proportional and derivative actions, to blood glucose concentrations with a constant time delay. The bedside-type artificial endocrine pancreas has been proven to be useful not only as a therapeutic tool for diabetes mellitus, but also as an elegant research tool for investigating the pathophysiology of the disease, by using the euglycemic hyperinsulinemic glucose clamp technique. The wearable type of closed-loop system has been developed recently. The breakthrough is the establishment of a needle-type glucose sensor. The development of closed-loop glycemic control systems that enable long-term physiological regulation has focused on implantable devices. Much effort has been expended to realize these devices.

Nonalcoholic fatty liver disease: a practical approach to evaluation and management

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common forms of chronic liver disease in the Western world. The rise in NAFLD is thought to be associated with the prevalence of metabolic syndrome. NASH is a subtype of NAFLD that may progress to cirrhosis and end stage liver disease. Although there are no approved treatment regimens for NAFLD or NASH, a number of different interventions are being tested. Meanwhile, most experts advocate that components of metabolic syndrome should be effectively treated.

Effects of antidiabetic drugs on dipeptidyl peptidase IV activity: nateglinide is an inhibitor of DPP IV and augments the antidiabetic activity of glucagon-like peptide-1

Dipeptidyl peptidase IV (DPP IV) is the primary inactivator of glucoregulatory incretin hormones. This has lead to development of DPP IV inhibitors as a new class of agents for the treatment of type 2 diabetes. Recent reports indicate that other antidiabetic drugs, such as metformin, may also have inhibitory effects on DPP IV activity. In this investigation we show that high concentrations of several antidiabetic drug classes, namely thiazolidinediones, sulphonylureas, meglitinides and morphilinoguanides can inhibit DPP IV. The strongest inhibitor nateglinide, the insulin-releasing meglitinide was effective at low therapeutically relevant concentrations as low as 25 micromol/l. Nateglinide also prevented the degradation of glucagon-like peptide-1 (GLP-1) by DPP IV in a time and concentration-dependent manner. In vitro nateglinide and GLP-1 effects on insulin release were additive. In vivo nateglinide improved the glucose-lowering and insulin-releasing activity of GLP-1 in obese-diabetic ob/ob mice. This was accompanied by significantly enhanced circulating concentrations of active GLP-1(7-36)amide and lower levels of DPP IV activity. Nateglinide similarly benefited the glucose and insulin responses to feeding in ob/ob mice and such actions were abolished by co-administration of exendin(9-39) and (Pro(3))GIP to block incretin hormone action. These data indicate that the use of nateglinide as a prandial insulin-releasing agent may partly rely on inhibition of GLP-1 degradation as well as beta-cell K(ATP) channel inhibition.

Beneficial metabolic effects of nateglinide versus acarbose in patients with newly-diagnosed type 2 diabetes

AIM

To investigate the acute and chronic effects of nateglinide versus acarbose on plasma asymmetric dimethylarginine (ADMA) levels and lipid profiles in patients with newly-diagnosed type 2 diabetes.

METHODS

A crossover trial of nateglinide and acarbose was conducted on 16 drug-naïve patients with newly-diagnosed type 2 diabetes during a total period of 9 weeks. Plasma glucose, serum insulin, free fatty acids (FFA), lipids and lipoproteins, and plasma ADMA were measured.

RESULTS

The efficiencies of a single dose of nateglinide (120 mg) and acarbose (50 mg) for lowering postprandial hyperglycemia were similar. Compared to acarbose, nateglinide significantly increased postprandial insulin release after a standard meal test in patients with type 2 diabetes. Nateglinide acutely decreased postprandial 120 min FFA concentrations and 240 min ADMA levels more significantly than acarbose. The fasting high-density lipoprotein cholesterol level increased and the low-density lipoprotein cholesterol level decreased significantly, but the fasting levels of triglycerides, total cholesterol, and ADMA were unchanged after 4 weeks of treatment with nateglinide. Acarbose did not affect fasting lipid profiles or the ADMA levels after 4 weeks of treatment.

CONCLUSION

These results suggest that the reduction of postprandial FFA and ADMA concentrations induced by nateglinide may be associated with the partial restoration of early-phase insulin secretion and may impart a cardiovascular advantage in comparison with acarbose.

Medical treatment of non-alcoholic steatohepatitis

There is no proven medical treatment of non-alcoholic steatohepatitis (NASH). Most prior therapeutic trials have had methodologic limitations. Insulin sensitizers are the more promising therapeutic candidates among categories that include antioxidants, lipid-lowering agents, and antiobesity drugs. The future will see the evaluation of novel agents and a comprehensive treatment strategy that addresses the risk factors for the metabolic syndrome. This article reviews the current status of medical management options for NASH.

Sulfonylureas and glinides exhibit peroxisome proliferator-activated receptor gamma activity: a combined virtual screening and biological assay approach

Most drugs currently employed in the treatment of type 2 diabetes either target the sulfonylurea receptor stimulating insulin release (sulfonylureas, glinides), or target the peroxisome proliferator-activated receptor (PPARgamma) improving insulin resistance (thiazolidinediones). Our work shows that sulfonylureas and glinides additionally bind to PPARgamma and exhibit PPARgamma agonistic activity. This activity was predicted in silico by virtual screening and confirmed in vitro in a binding assay, a transactivation assay, and by measuring the expression of PPARgamma target genes. Among the measured compounds, gliquidone and glipizide (two sulfonylureas), as well as nateglinide (a glinide), exhibit PPARgamma agonistic activity at concentrations comparable with those reached under pharmacological treatment. The most active of these compounds, gliquidone, is shown to be as potent as pioglitazone at inducing PPARgamma target gene expression. This dual mode of action of sulfonylureas and glinides may open new perspectives for the molecular pharmacology of antidiabetic drugs, because it provides evidence that drugs can be designed that target both the sulfonylurea receptor and PPARgamma. Targeting both receptors could increase pancreatic insulin secretion and improve insulin resistance. Glinides, sulfonylureas, and other acidified sulfonamides may be promising leads in the development of new PPARgamma agonists. In addition, we provide a unified concept of the PPARgamma binding ability of seemingly disparate compound classes.

Insulin and nateglinide reduce monocyte adhesion to endothelial cells in Goto-Kakizaki rats exhibiting repetitive blood glucose fluctuation

Epidemiological studies demonstrated the importance of postprandial hyperglycemia on the progression of atherosclerosis. However, whether treatment of postprandial hyperglycemia by insulin or insulin secretagogues has a beneficial effect on atherosclerosis has not been elucidated. To elucidate the effects of reduction of postprandial rise of blood glucose by insulin and nateglinide on monocyte adhesion to endothelial cells, we used non-obese type 2 diabetic Goto-Kakizaki (GK) rats fed twice daily, as a model of repetitive postprandial hyperglycemia. We investigated the effects of insulin injection and nateglinide administration just before each meal for 12 weeks on monocyte adhesion to endothelial cells. By setting the doses of insulin and nateglinide, both treatment significantly reduced postprandial hyperglycemia without significant reduction of HbA1c. Nateglinide also reduced serum insulin level just after 1 h meal. Both nateglinide and insulin therapy reduced the number of monocytes adherent to the aortic endothelial layer. Nateglinide, but not insulin, reduced intimal thickness of the thoracic aorta. While increased serum insulin level might be regarded as a factor responsible for the progression of atherosclerosis, our data showed that treatment with pre-meal insulin or nateglinide, which reduces postprandial hyperglycemia, reduced monocyte adhesion to endothelial cells.