Effect of KAD-1229, a nonsulfonylurea hypoglycemic agent, on plasma glucose and insulin in streptozotocin-induced diabetic dogs

Hypoglycemic agents with a rapid onset and short duration of action should be useful for controlling postprandial hyperglycemia. Our aim was to establish a diabetes mellitus model in dogs, and then during an oral glucose tolerance test to compare the hypoglycemic effect and insulinotropic action of KAD-1229, a new hypoglycemic agent, with that of gliclazide, a conventional sulfonylurea. In this model, KAD-1229 reduced the increase in plasma glucose level without producing hypoglycemia. Gliclazide had a weaker effect on reduction of the glucose increase and caused hypoglycemia via a significantly raised insulin secretion in the late phase. A rapid insulinotropic action of KAD-1229 was clearly observed in the portal venous blood. The results suggest that in type 2 diabetes caused by, at least, insulin deficiency, KAD-1229 may improve impaired insulin secretion in the early phase and attenuate hyperglycemia without causing a sustained hypoglycemia.     

Effect of a non-sulphonylurea hypoglycaemic agent, KAD-1229 on hormone secretion in the isolated perfused pancreas of the rat.

1. We examined the cooperative effect of a newly synthesized oral hypoglycaemic agent, KAD-1229 with glucose on insulin, glucagon and somatostatin secretion in the isolated perfused pancreas of the rat. 2. KAD-1229 stimulated concentration-dependently the first phase of insulin secretion without the second phase in the presence of 2.8 mM glucose, while it stimulated both the first and the second phase of insulin release in the presence of 5.6 mM glucose. It was confirmed that the first phase of insulin release is depolarization-induced release with no other additional signal transduction. 3. KAD-1229 also enhanced insulin release evoked by 16.7 mM glucose, a concentration known to inhibit the ATP-sensitive K+ current completely. 4. A low concentration (2.8 mM) of glucose stimulated somatostatin release transiently, while a higher concentration (16.7 mM) of glucose exerted a sustained stimulation. KAD-1229 stimulated somatostatin secretion in a concentration-dependent manner irrespective of glucose concentrations. 5. When glucagon release was stimulated with 2.8 mM glucose, KAD-1229 inhibited this hypoglycaemia-induced glucagon secretion. 6. When pancreata from rats pretreated with streptozotocin (STZ) 60 mg kg-1 were perfused, the basal secretion of glucagon was markedly elevated, and the glucagon response to the low glucose was abolished. Further, the insulin and somatostatin responses to KAD-1229 were largely attenuated. KAD-1229 showed transient enhancement followed by inhibition of the glucagon release from the STZ-pretreated rat pancreas. 7. We conclude that KAD-1229 stimulates insulin and somatostatin release, while it inhibits glucagon release following transient stimulation.     

Study of the insulinotropic effect of the novel antihyperglycemic agent KAD-1229 using HIT T15 cells,a hamster's insulinoma cell line

The insulinotropic effect of (+)-monocalcium bis [(2S)-2-benzyl-3-(cis-hexahydro-2-isoindolinyl-carbonyl)propionate] dihydrate (CAS 145375-43-5, KAD-1229) was assessed by comparing it with those of glibenclamide (CAS 10238-21-8), nateglinide (CAS 105816-04-4), and repaglinide (CAS 135062-02-1) using HIT T15 cells, a hamster insulinoma cell line. Although their potencies were different, KAD-1229, glibenclamide, nateglinide, and repaglinide all concentration-dependently and significantly induced insulin release from these cells. Further, each agent displaced the binding of 3H-glibenclamide to the cell membrane and inhibited 86Rb+ efflux from the cells. These results indicate that KAD-1229, glibenclamide, nateglinide, and repaglinide each exert their insulinotropic effect by binding to the glibenclamide binding sites (sulfonylurea receptors) on pancreatic beta-cells and closing K+ channels. Diazoxide, a K+ channel opener, and nitrendipine, a Ca2+ blocker, suppressed the insulin release induced by KAD-1229 or glibenclamide. These results demonstrate that the insulinotropic actions of KAD-1229 and glibenclamide involve similar underlying pathways.     

Absence of exacerbation of myocardial stunning in anesthetized dogs treated with KAD-1229, a novel hypoglycemic agent.

The effect of (+)-momocalcium bis[(2S,3a,7a-cis)-alpha-benzylhexahydro-gamma-oxo-2-isoindolinebutyrate]dihydrate (KAD-1229), a novel hypoglycemic agent with a chemical structure different from that of the sulfonylureas, on myocardial stunning was assessed in anesthetized dogs by comparison with that of glibenclamide, a sulfonylurea. Even though their hypoglycemic effects were of similar magnitude, glibenclamide (1 mg/kg, i.v.), but not KAD-1229, exacerbated the myocardial stunning induced by occlusion/reperfusion of the descending coronary artery. In a receptor-binding experiment, unlabeled glibenclamide completely inhibited [(3)H]glibenclamide binding to the myocardium, but KAD-1229 did not. These results suggest that the difference in binding properties of KAD-1229 and glibenclamide toward cardiac sulfonylurea receptors is one of the causes of their different effects on myocardial stunning. It is likely that KAD-1229 is highly specific for pancreatic sulfonylurea receptors and is speculated to be a safer hypoglycemic agent than, at least, glibenclamide.     

Inhibition of heterologously expressed cystic fibrosis transmembrane conductance regulator Cl- channels by non-sulphonylurea hypoglycaemic agents.

1. Hypoglycaemia-inducing sulphonylureas, such as glibenclamide, inhibit cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels. In search of modulators of CFTR, we investigated the effects of the non-sulphonylurea hypoglycaemic agents meglitinide, repaglinide, and mitiglinide (KAD-1229) on CFTR Cl- channels in excised inside-out membrane patches from C127 cells expressing wild-type human CFTR. 2. When added to the intracellular solution, meglitinide and mitiglinide inhibited CFTR Cl- currents with half-maximal concentrations of 164+/-19 microM and 148+/-36 microM, respectively. However, repaglinide only weakly inhibited CFTR Cl- currents. 3. To understand better how non-sulphonylurea hypoglycaemic agents inhibit CFTR, we studied single channels. Channel blockade by both meglitinide and mitiglinide was characterized by flickery closures and a significant decrease in open probability (Po). In contrast, repaglinide was without effect on either channel gating or Po, but caused a small decrease in single-channel current amplitude. 4. Analysis of the dwell time distributions of single channels indicated that both meglitinide and mitiglinide greatly decreased the open time of CFTR. Mitiglinide-induced channel closures were about 3-fold longer than those of meglitinide. 5. Inhibition of CFTR by meglitinide and mitiglinide was voltage-dependent: at positive voltages channel blockade was relieved. 6. The data demonstrate that non-sulphonylurea hypoglycaemic agents inhibit CFTR. This indicates that these agents have a wider specificity of action than previously recognized. Like glibenclamide, non-sulphonylurea hypoglycaemic agents may inhibit CFTR by occluding the channel pore and preventing Cl- permeation.     

The potential role of valsartan + AHU377 (LCZ696) in the treatment of heart failure

Current treatments for non-insulin dependent diabetes mellitus (NIDDM) remain far from ideal. The universal finding of islet dysfunction characterised by the absence of first phase insulin secretion, even prior to the level of hyperglycaemia diagnostic of NIDDM, challenges the rationale for treatments that only enhance insulin action. To date, however, the sulfonylureas are the only insulin secretagogues available and even the most rapid acting of these fail to restore early insulin release in response to meals. Four novel non-sulfonylurea insulin secretagogues are in advanced clinical development: A-4166, KAD-1229, BTS 67 582 and repaglinide. These promising new agents control prandial hyperglycaemia by augmenting the early insulin response to meals. Preclinical and early clinical data suggest that their potencies vary considerably, as do their pharmacokinetics and, importantly, their pharmacodynamics. The two shortest-acting compounds, A-4166 and KAD-1229, will be developed to be taken prior to each main meal, while the slower, longer duration agents, repaglinide and BTS 67 582, may be developed to be taken twice daily. With a sufficiently rapid onset and short duration of action, the new non-sulfonylurea insulin secretagogues may improve or even restore the impairment of early insulin secretion without inducing the prolonged hyperinsulinaemia characteristic of sulfonylureas. Treatment with these new agents will immediately improve prandial glucose control and with continued treatment these agents are expected to improve the overall metabolic state. Furthermore, a short-acting secretagogue will have minimal propensity to elicit prolonged or delayed hypoglycaemia and it is expected that by minimising chronic hyperinsulinaemia the weight gain that accompanies sulfonylurea treatment will be avoided. In summary, the new non-sulfonylurea insulin secretagogues will make an important contribution to the limited and inadequate armamentarium currently available for the treatment of NIDDM, and their use in combination with insulin sensitising agents may provide, for the first time, an approximation to ideal metabolic control in NIDDM.     

Effects of combination of mitiglinide with various oral antidiabetic drugs in streptozotocin‐nicotinamide‐induced type 2 diabetic rats and Zucker fatty rats

We examined the effects of combining the rapid insulin secretagogue, mitiglinide, with various oral hypoglycaemic drugs including biguanides, pioglitazone, α‐glucosidase inhibitors, and sodium‐glucose co‐transporter 2 inhibitors in a rat model of type 2 diabetes. The oral glucose tolerance test (OGTT) using glucose, sucrose, or a liquid meal was used to compare the effects of mitiglinide with those of the four oral hypoglycaemic drugs and examine their combined effects on blood glucose levels and insulin secretion in the rat model. The combination of mitiglinide with other oral hypoglycaemic drugs suppressed the plasma glucose levels more than either agent did alone. Furthermore, the combination of these agents decreased insulin secretion more than mitiglinide did alone. These results indicate that mitiglinide is suitable for use in combination with other hypoglycaemic drugs because it inhibits postprandial hyperglycaemia by rapidly stimulating insulin secretion.     

Comparison of efficacies of a dipeptidyl peptidase IV inhibitor and alpha-glucosidase inhibitors in oral carbohydrate and meal tolerance tests and the effects of their combination in mice

E3024 (3-but-2-ynyl-5-methyl-2-piperazin-1-yl-3,5-dihydro-4H-imidazo[4,5-d]pyridazin-4-one tosylate) is a dipeptidyl peptidase IV (DPP-IV) inhibitor. Since the target of both DPP-IV inhibitors and alpha-glucosidase inhibitors is the lowering of postprandial hyperglycemia, we compared antihyperglycemic effects for E3024 and alpha-glucosidase inhibitors in various oral carbohydrate and meal tolerance tests using normal mice. In addition, we investigated the combination effects of E3024 and voglibose on blood glucose levels in a meal tolerance test using mice fed a high-fat diet. ER-235516-15 (the trifluoroacetate salt form of E3024, 1 mg/kg) lowered glucose excursions consistently, regardless of the kind of carbohydrate loaded. However, the efficacy of acarbose (10 mg/kg) and of voglibose (0.1 mg/kg) varied with the type of carbohydrate administered. The combination of E3024 (3 mg/kg) and voglibose (0.3 mg/kg) improved glucose tolerance additively, with the highest plasma active glucagon-like peptide-1 levels. This study shows that compared to alpha-glucosidase inhibitors, DPP-IV inhibitors may have more consistent efficacy to reduce postprandial hyperglycemia, independent of the types of carbohydrate contained in a meal, and that the combination of a DPP-IV inhibitor and an alpha-glucosidase inhibitor is expected to be a promising option for lowering postprandial hyperglycemia.     

New non-sulfonylurea insulin secretagogues

Current treatments for non-insulin dependent diabetes mellitus (NIDDM) remain far from ideal. The universal finding of islet dysfunction characterised by the absence of first phase insulin secretion, even prior to the level of hyperglycaemia diagnostic of NIDDM, challenges the rationale for treatments that only enhance insulin action. To date, however, the sulfonylureas are the only insulin secretagogues available and even the most rapid acting of these fail to restore early insulin release in response to meals. Four novel non-sulfonylurea insulin secretagogues are in advanced clinical development: A-4166, KAD-1229, BTS 67 582 and repaglinide. These promising new agents control prandial hyperglycaemia by augmenting the early insulin response to meals. Preclinical and early clinical data suggest that their potencies vary considerably, as do their pharmacokinetics and, importantly, their pharmacodynamics. The two shortest-acting compounds, A-4166 and KAD-1229, will be developed to be taken prior to each main meal, while the slower, longer duration agents, repaglinide and BTS 67 582, may be developed to be taken twice daily. With a sufficiently rapid onset and short duration of action, the new non-sulfonylurea insulin secretagogues may improve or even restore the impairment of early insulin secretion without inducing the prolonged hyperinsulinaemia characteristic of sulfonylureas. Treatment with these new agents will immediately improve prandial glucose control and with continued treatment these agents are expected to improve the overall metabolic state. Furthermore, a short-acting secretagogue will have minimal propensity to elicit prolonged or delayed hypoglycaemia and it is expected that by minimising chronic hyperinsulinaemia the weight gain that accompanies sulfonylurea treatment will be avoided. In summary, the new non-sulfonylurea insulin secretagogues will make an important contribution to the limited and inadequate armamentarium currently available for the treatment of NIDDM, and their use in combination with insulin sensitising agents may provide, for the first time, an approximation to ideal metabolic control in NIDDM.     

Defining the role of insulin lispro in the management of postprandial hyperglycaemia in patients with type 2 diabetes mellitus

The role of postprandial hyperglycaemia in contributing to the risk of both micro- and macrovascular complications in patients with diabetes mellitus is being increasingly recognized. In type 2 diabetes, there is a progressive shift in the relative contributions of postprandial and fasting hyperglycaemia to the overall glycaemic control as the disease progresses. For patients with fairly good glycaemic control (glycosylated haemoglobin [HbA(1c)] <8.5%), postprandial hyperglycaemia makes a relatively greater contribution to the overall glycaemic load than fasting hyperglycaemia, but in patients with poorer control, the relative contribution of the two states to the overall glycaemic load is reversed. This finding, coupled with epidemiological evidence that elevated postprandial glucose concentration is an independent risk factor for cardiovascular disease (CVD), and is associated with a greater CVD risk than elevated fasting glucose, points to the need to monitor and target postprandial glucose, as well as fasting glucose and HbA(1c) levels, when optimizing insulin therapy for patients with type 2 diabetes. When insulin therapy becomes necessary in patients with type 2 diabetes who can no longer be controlled with oral antihyperglycaemic therapy, use of short-acting insulin analogues with a rapid onset of action and capable of controlling postprandial glycaemic excursions when injected immediately before a meal, has advantages over regular human insulin in that they provide a more favourable time-action profile that mimics normal physiological insulin secretion. Among the available rapid-acting insulin analogues, insulin lispro has been shown to reduce postprandial glucose concentrations to a significantly greater degree than regular human insulin in patients with type 2 diabetes. Moreover, premixed combinations of insulin lispro with the longer acting analogue neutral insulin lispro protamine suspension in 25% : 75% or 50% : 50% combinations are significantly more effective in lowering postprandial blood glucose concentrations than premixed regular human insulin plus neutral protamine Hagedorn (NPH) 30% : 70%. The premixed insulin lispro combinations offer the advantage of fewer daily injections than intensive insulin therapy, and the convenience of not having to mix insulin preparations manually. Although it has yet to be conclusively established that targeting postprandial hyperglycaemia reduces CVD risk, the potential benefits of improved postprandial and interprandial hyperglycaemia favour the use of newer insulin analogues, such as insulin lispro and insulin lispro mixes, over conventional insulin therapy, whenever insulin therapy becomes necessary in patients with type 2 diabetes.     

Glipizide increases plasma insulin but not C-peptide level after a standardized breakfast in type 2 diabetic patients

Summary Peripheral blood glucose, plasma insulin and C-peptide levels were investigated after giving a standardized breakfast (500 kcal, 60g carbohydrates) to 10 nonobese Type 2 diabetic patients previously treated by diet alone. Each patient received at random, at 1 week intervals, either 5 mg glipizide (meal + glipizide) or a placebo (meal alone) 30 min before breakfast. Basal values of blood glucose, plasma insulin and C-peptide were similar on both occasions. After meal + glipizide, the blood glucose increase was sharply limited whereas the rise in plasma insulin was steeper and reached twice as high a level. In contrast, the rise in plasma C-peptide was similar in both conditions. Consequently, the areas under the curves (0–300 min) showed a marked reduction in blood glucose after meal + glipizide (2289±149 versus 3101±169 mmol·min/l; 2p<0.001), associated with a significant increase in plasma insulin (14219±3261 versus 7591±1173 µU·min/ml; 2p<0.025) but no significant change in plasma C-peptide (342±45 versus 326±34 pmol·min/ml; N.S.). The insulin/C-peptide molar ratio was thus significantly increased after meal + glipizide (0.41±0.06 versus 0.23±0.04 at the 60th min; 2p<0.02). The dissociation between the responses of insulin and C-peptide suggests that a single dose of 5 mg glipizide in Type 2 diabetic subjects may enhance availability of peripheral insulin by extrapancreatic mechanism(s). This phenomenon may result in a higher circulating level of the hormone and therefore represent a further mode of action of sulphonylureas. Finally, the usual concept that peripheral insulin levels reflect true insulin secretion may be misleading in studies dealing with sulphonylureas.     

Alpha-adrenoceptor involvement in catecholamine-induced hyperglycaemia in conscious fasted rabbits.

In conscious fasted rabbits an intravenous infusion of phenylephrine (20 micrograms kg-1 min-1) induced hyperglycaemia. The increase in blood glucose was accompanied by a modest increase in insulin secretion and a reduction of liver glycogen. Muscle glycogen and blood lactate levels were not altered by treatment with phenylephrine. Prazosin, 1 mg kg-1 s.c., partially attenuated phenylephrine-induced hyperglycaemia. Phenoxybenzamine infusion (16.6 micrograms kg-1 min-1) for 15 min suppressed the increase in blood glucose and the reduction in liver glycogen evoked by phenylephrine. This alpha-adrenoceptor blocker also clearly attenuated the blood glucose elevation observed on infusing adrenaline at 0.3 microgram kg-1 min-1. Blockade by phenoxybenzamine of phenylephrine- and adrenaline-induced hyperglycaemia was not accompanied by a significant increase in immunoreactive insulin plasma levels. Yohimbine infused at a rate of 20 micrograms kg-1 min-1, also completely blocked phenylephrine-induced hyperglycaemia. This suppressor effect was accompanied by a marked rebound in insulin secretion. It is concluded that in normal fasted rabbits stimulation of alpha-adrenoceptors induces hyperglycaemia. The increase in blood glucose depends mainly on liver glycogenolysis and inhibition of insulin secretion. Separate blockade of each component suffices to reduce alpha-adrenoceptor-mediated hyperglycaemia.     

Paradoxical short-term effects of cyproheptadine on insulin and glucagon release in the rat.

The administration of cyproheptadine (25 mg/kg; i.p.) resulted in an increase of plasma insulin and glucagon (measured using 30 K antibody) 30, 60 and 120 min after injection to fasted rats. This dose of cyproheptadine also induced a hyperglycemia whereas a lower dose (5 mg/kg; i.p.), which did not alter plasma hormone levels, was associated with a hypoglycemia. Fed rats showed a reduction of plasma insulin with a similar elevation of blood glucose after cyproheptadine. Administration of an exogenous load of arginine resulted in increases of plasma insulin and glucagon of a greater magnitude than induced by cyproheptadine, however, cyproheptadine pretreatment (25 mg/kg) completely suppressed the pancreatic response to the amino acid, resulting in blood hormone levels similar to values seen after cyproheptadine administered alone. Cyproheptadine pretreatment also prevented the hyperinsulinemia and hypoglucagonemia resulting from glucose loading. alpha-Adrenergic receptor blockade (with phentolamine), beta adrenergic receptor blockade (with propranolol) and adrenodemedullation did not alter pancreatic responsiveness to the drug.     

Glycemic/metabolic responses to identical meal tolerance tests at breakfast,lunch and dinner in Japanese patients with type 2 diabetes mellitus treated with a dipeptidyl peptidase-4 inhibitor and the effects of adding a mitiglinide/voglibose fixed-dose combination

Background: The effects of the mitiglinide/voglibose fixed-dose combination on postprandial glycemic/metabolic responses in patients with type 2 diabetes mellitus (T2DM) treated with dipeptidyl peptidase-4 (DPP-4) inhibitors are unknown.

Methods: Twelve T2DM patients treated with a DPP-4 inhibitor underwent identical meal tolerance tests (MTTs) at breakfast, lunch and dinner, before and 2 – 3 weeks after treatment with a fixed-dose combination of mitiglinide 10 mg and voglibose 0.2 mg (combination). Patients were randomized in a cross-over fashion to administer the combination either three-times-daily before each meal or twice-daily before breakfast and dinner. Glycemic/metabolic responses were evaluated at 0, 30, 60 and 120 min in each MTT.

Results: Three-times-daily administration of the combination significantly suppressed postprandial hyperglycemia after each meal, particularly after lunch and dinner. Active glucagon-like peptide-1 levels increased significantly after each meal, as did early-phase insulin secretion without excessive insulin secretion. Postprandial hyperglycemia after lunch was significantly greater after twice-daily than three-times-daily administration, but there were no clinically relevant differences in other metabolic responses.

Conclusion: This study revealed that adding the mitiglinide/voglibose combination to a DPP-4 inhibitor elicited additive improvements in postprandial glycemic/metabolic responses assessed using MTTs at breakfast, lunch and dinner with identical meal compositions.     

伏格列波糖片治疗2型糖尿病的临床疗效及不良反应

目的探讨伏格列波糖片治疗2型糖尿病的临床疗效及不良反应。方法选择我院2011年1月至2012年2月住院治疗的2型糖尿病患者76例分为观察组(n=38)与对照组(n=38),观察组采用伏格列波糖片治疗,对照组采用阿卡波糖片治疗。观察比较两组患者的治疗效果及不良反应。结果两组患者治疗后空腹血糖(FPG)、餐后2h血糖、糖化血红蛋白(HbA1c)均低于治疗前,差异均有统计学意义(P<0.05),观察组FPG、餐后2h血糖、HbA1c降低优于对照组,但两组治疗后比较差异无统计学意义(P>0.05)。观察组不良反应发生率明显低于对照组,差异有统计学意义(P<0.05)。两组均未见其他严重不良反应发生。结论伏格列波糖片治疗2型糖尿病不良反应少,并发症风险能有效降低,临床效果较好,是临床治疗2型糖尿病的首选。     

Insulin requirement for the antihyperglycaemic effect of metformin.

1. Insulin-dependent diabetic BB/S rats with little or no endogenous insulin were used to determine whether insulin is required for the acute antihyperglycaemic effect of metformin (dimethylbiguanide). 2. Metformin (250 mg kg-1, intrajejunally) did not lower the hyperglycaemia in BB/S rats in the absence of exogenous insulin, but metformin increased by 69% (P < 0.05) the blood glucose-lowering effect of exogenous insulin. 3. Metformin (250 mg kg-1, intrajejunally) improved glucose disposal in rats with a normal insulin response to an intravenous glucose challenge. Plasma glucose disappearance was increased from 0.7 +/- 0.1 to 2.5 +/- 0.1% min-1 (P < 0.05). 3. When the insulin response to glucose was suppressed with somatostatin and diazoxide, metformin improved glucose disposal to a similar extent to that in rats with a normal insulin response. Plasma glucose disappearance was increased from 0.24 +/- 0.02 to 1.0 +/- 0.1% min-1 (P < 0.01). 5. The results indicate that insulin is required for the acute antihyperglycaemic effect of metformin, but the extent of this effect is not proportional to the prevailing insulin concentration.     

Switching α-Glucosidase Inhibitors to Miglitol Reduced Glucose Fluctuations and Circulating Cardiovascular Disease Risk Factors in Type 2 Diabetic Japanese Patients

Background and Objectives

In this study we examined the effects of switching α-glucosidase inhibitors (α-GI) from acarbose or voglibose to miglitol on glucose fluctuations and circulating concentrations of cardiovascular disease risk factors, such as soluble adhesion molecules (sE-selectin, sICAM-1 and sVCAM-1), a chemokine monocyte chemoattractant protein (MCP)-1, plasminogen activator inhibitor-1, and fatty acid-binding protein 4, in type 2 diabetic patients for 3 months.

Methods

We enrolled 47 Japanese patients with type 2 diabetes, with HbA_1c levels with 7.26 ± 0.5 % (mean ± standard deviation), and who were treated with the highest approved dose of acarbose (100 mg/meal) or voglibose (0.3 mg/meal) in combination with insulin or sulfonylurea. Patients’ prior α-GIs were switched to a medium dose of miglitol (50 mg/meal), and the new treatments were maintained for 3 months. Thirty-five patients who completed the 3-month study and provided serum samples were analyzed.

Results

The switch to miglitol for 3 months did not affect HbA_1c, fasting glucose, triglycerides, total-cholesterol or C-reactive protein levels, or result in any adverse events. Glucose fluctuations were significantly improved by the change in treatment (M-value: 10.54 ± 4.32 to 8.36 ± 2.54), while serum protein concentrations of MCP-1 (525.04 ± 288.06–428.11 ± 163.78 pg/mL) and sE-selectin (18.65 ± 9.77–14.50 ± 6.26 ng/mL) were suppressed.

Conclusion

Our results suggest that switching from acarbose or voglibose to miglitol for 3 months suppressed glucose fluctuations and serum protein levels of MCP-1 and sE-selectin in type 2 diabetic Japanese patients, with fewer adverse effects.     

D-chiro-inositol found in Cucurbita ficifolia (Cucurbitaceae) fruit extracts plays the hypoglycaemic role in streptozocin-diabetic rats

Cucurbita ficifolia is commonly used as an antihyperglycaemic agent in Asia. However, the mechanism of its action is unknown. Chemically synthesized D-chiro-inositol (D-CI), a component of an insulin mediator, has been demonstrated to have antihyperglycaemic effects in rats. In this study, we found that C. ficifolia contained fairly high levels of D-CI, thus, C. ficifolia may be a natural source of D-CI for reducing blood glucose concentrations in diabetics. We evaluated C. ficifolia fruit extract, containing D-CI, for its antihyperglycaemic effect in streptozotocin-induced diabetic rats. Oral administration of C. ficifolia fruit extract containing 10 or 20 mg D-CI kg(-1) body weight for 30 days resulted in significantly lowered levels of blood glucose, and increased levels of hepatic glycogen, total haemoglobin and plasma insulin. An oral glucose tolerance test was performed in fasted diabetic and normal rats, in which there was a significant improvement in blood glucose tolerance in the diabetic rats treated with C. ficifolia fruit extract. The effects were compared with 20 mg kg(-1) body weight chemically synthesized D-CI. Findings from this study demonstrated that C. ficifolia fruit extract was an effective source of D-CI for its hypoglycaemic effects in rats, and therefore may be useful in the treatment of diabetes.     

Effects of sitagliptin or mitiglinide as an add-on to acarbose on daily blood glucose fluctuations measured by 72 h subcutaneous continuous glucose monitoring in Japanese patients with type 2 diabetes: a prospective randomized study

Objective: Postprandial hyperglycemia and blood glucose fluctuations increase the risk of macroangiopathy in patients with type 2 diabetes mellitus (T2DM). However, few studies have examined the effects of oral hypoglycemic drugs on blood glucose fluctuations in daily life.

Methods: Twenty-nine T2DM patients treated with acarbose were randomized to receive either sitagliptin (14 patients) or mitiglinide (15 patients) together with acarbose for 4 weeks. Patients were then switched to a combination of 10 mg mitiglinide and 0.2 mg voglibose for 4 weeks. All patients wore a continuous glucose monitoring (CGM) device for 5 – 7 days in week 3 of each treatment period.

Results: The percentage of blood glucose levels in the hyperglycemic range, blood glucose indices derived from 24-h CGM profiles and the glycemic parameters (HbA1c, glycated albumin and fasting plasma glucose) were significantly improved by adding sitagliptin or mitiglinide to ongoing acarbose therapy. These parameters also tended to improve in the mitiglinide/voglibose combination period.

Conclusion: Daily blood glucose fluctuations were significantly improved by adding sitagliptin or mitiglinide to acarbose, and improved after switching to the mitiglinide/voglibose combination. Larger controlled studies are needed to verify the effects of adding sitagliptin or mitiglinide to acarbose on glucose fluctuations.     

Nateglinide suppresses postprandial hypertriglyceridemia in Zucker fatty rats and Goto-Kakizaki rats: comparison with voglibose and glibenclamide

Postprandial hypertriglyceridemia, as well as postprandial hyperglycemia, are important factors contributing to the development of cardiovascular disease in patients with type 2 diabetes. Nateglinide is a recently approved antidiabetic that suppresses postprandial hyperglycemia by stimulating the early phase of insulin secretion. In the present study, we investigated the effects of nateglinide on postprandial hypertriglyceridemia in obese Zucker fatty (ZF) rats and non-obese diabetic Goto-Kakizaki (GK) rats. Administration of an oral fat load caused marked hypertriglyceridemia with a peak at 2 h in ZF and GK rats. Nateglinide (50 mg/kg) significantly suppressed the increase of plasma triglycerides after fat loading in both types of rat (delta AUC [0-4 h]: 15+/-69 mg.h/dl for nateglinide vs. 838+/-100 mg.h/dl for vehicle in ZF rats; p<0.01, 81+/-22 mg x h/dl for nateglinide vs. 164+/-17 mg.h/dl for vehicle in GK rats; p<0.01). In contrast, other antidiabetic agents (voglibose and glibenclamide) did not show a significant effect on the increase of triglycerides after fat loading. The triglyceride components suppressed by nateglinide were mainly at the origin and in the pre beta subfraction on agarose gel electrophoresis, suggesting that chylomicrons and very low density lipoproteins were decreased. Plasma insulin levels were significantly increased at 30 min in nateglinide-treated rats, but not in voglibose- or glibenclamide-treated rats. These results suggest that nateglinide not only suppresses postprandial hyperglycemia, but also suppresses postprandial hypertriglyceridemia, by promoting rapid and pulsatile insulin secretion in patients with type 2 diabetes.