Postprandial hyperglycaemia and vascular damage--the benefits of acarbose

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.

The effects of acarbose treatment on cardiovascular risk factors in impaired glucose tolerance and diabetic patients: a systematic review and dose-response meta-analysis of randomized clinical trials

Acarbose (ACB) seems to be an effective drug in the management of cardiovascular risk factors. However, no previous meta-analysis of randomized controlled trials (RCTs) has been done to evaluate the effects of ACB on cardiovascular risk factors on impaired glucose tolerance (IGT), type 2 diabetes mellitus (T2D), and type 1 diabetes mellitus (T1D). We comprehensively searched electronic databases including Scopus, Web of Science, and PubMed for RCTs for related keywords up to September 2022. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence interval (CI). The pooled analysis demonstrated that ACB treatment had a significant effect on fasting blood glucose (FBG) (WMD = -3.55 mg/dL; 95%CI: -6.29, -0.81; p = 0.011), fasting insulin (WMD = -6.73 pmoL/L; 95%CI: -10.37, -3.10; p < 0.001), HbA1c [WMD = -0.32%; 95%CI: -0.45, -0.20; p < 0.001], body weight (WMD = -1.25 kg; 95%CI: -1.79, -0.75; p < 0.001), body mass index (BMI) (WMD = -0.64 kg/m2; 95%CI: -0.92, -0.37; p < 0.001), tumor necrosis factor-alpha (TNF-α) (WMD = -2.70 pg/mL, 95%CI: -5.25, -0.16; p = 0.037), leptin (WMD = -1.58 ng/mL; 95%CI: -2.82, -0.35; p = 0.012), alanine transaminase (ALT) (WMD = 0.71 U/L; 95%CI: -0.31, 1.85; p = 0.164), triglyceride (TG) (WMD = -13.89 mg/dL; 95%CI: -20.69, -7.09; p < 0.001), total cholesterol (TC) (WMD = -2.26 mg/dL; 95%CI: -4.18, -0.34; p = 0.021), systolic blood pressure (SBP) (WMD = -1.29 mmHg; 95%CI: -2.44, -0.15; p = 0.027), and diastolic blood pressure (DBP) (WMD = 0.02 mmHg; 95%CI: -0.41, 0.45; p = 0.925) in an intervention group, compared with a placebo group. The non-linear dose-response analysis showed that ACB reduces the TC in trial duration by >50 weeks, and 180 mg/day is more effective for the decrement of CRP. ACB can improve lipid profiles, glycemic indices, anthropometric indices, and inflammatory markers in T2D, T1D, and IGT patients.

In vivo photoacoustic monitoring of vasoconstriction induced by acute hyperglycemia

Postprandial hyperglycemia, blood glucose spikes, induces endothelial dysfunction, increasing cardiovascular risks. Endothelial dysfunction leads to vasoconstriction, and observation of this phenomenon is important for understanding acute hyperglycemia. However, high-resolution imaging of microvessels during acute hyperglycemia has not been fully developed. Here, we demonstrate that photoacoustic microscopy can noninvasively monitor morphological changes in blood vessels of live animals' extremities when blood glucose rises rapidly. As blood glucose level rose from 100 to 400 mg/dL following intraperitoneal glucose injection, heart/breath rate, and body temperature remained constant, but arterioles constricted by approximately -5.7 ± 1.1% within 20 min, and gradually recovered for another 40 min. In contrast, venular diameters remained within about 0.6 ± 1.5% during arteriolar constriction. Our results experimentally and statistically demonstrate that acute hyperglycemia produces transitory vasoconstriction in arterioles, with an opposite trend of change in blood glucose. These findings could help understanding vascular glucose homeostasis and the relationship between diabetes and cardiovascular diseases.

Derivation and validation of a clinical prediction model for assessing the risk of lower extremity amputation in patients with type 2 diabetes

AIM

This study aims to develop and validate a lower extremity amputation (LEA) risk score system in persons with type 2 diabetes.

METHODS

A retrospective population-based cohort study was conducted among eligible 21,484 participants in the derivation set and 10,742 participants in the validation set who were enrolled in the Taiwan National Diabetes Care Management Program. The risk score system was developed following the steps proposed by the Framingham Heart Study with a Cox proportional hazards model algorithm. Discrimination ability was assessed by the receiver operating characteristic curve, and calibration was performed by Hosmer-Lemeshow test.

RESULTS

A total of 504 patients developed LEA at an average follow-up of 7.4 years. The point scores were derived from 15 predictors as follows: age, gender, duration of type 2 diabetes, body mass index, HbA1c, triglyceride, eGFR, variation of fasting blood glucose, comorbidities of stroke, diabetes retinopathy, hypoglycemia and foot ulcer, anti-diabetes medication, and use of diuretics and nitrates. The c-statistics for predicting 3-, 5-, and 8-year LEA risks were 0.80 [95% confidence interval (CI) 0.76-0.83], 0.78 (0.75-0.81), and 0.76 (0.74-0.79) in the derivation set, respectively, and 0.81 (0.76-0.85), 0.77 (0.73-0.81), and 0.74 (0.71-0.77) in the validation set, respectively.

CONCLUSIONS

A new risk score for LEA was developed and validated in the clinical setting with good discriminatory ability. Poor glycemic control, glucose variation, comorbidities, and medication use were identified as predictive factors for LEA in patients with type 2 diabetes.

Glycaemic target attainment in people with Type 2 diabetes treated with insulin glargine/lixisenatide fixed-ratio combination: a post hoc analysis of the LixiLan-O and LixiLan-L trials

AIMS

Both fasting (FPG) and postprandial plasma glucose (PPG) contribute to HbA_1c levels. We investigated the relationship between achievement of American Diabetes Association (ADA) and American Association of Clinical Endocrinologists (AACE) recommended FPG and/or PPG targets and glycaemic efficacy outcomes in two trials.

METHODS

In this post hoc analysis, data from participants with Type 2 diabetes in the phase 3 LixiLan-O (NCT02058147) and LixiLan-L (NCT02058160) trials were evaluated to compare the relationship between achievement of society-recommended FPG and/or PPG targets and efficacy (HbA_1c change, HbA_1c goal attainment, weight change) and safety outcomes in the treatment groups.

RESULTS

Across treatment arms, iGlarLixi achieved the highest proportion of participants meeting both ADA- and AACE-recommended FPG and PPG targets at study end in both trials. A higher proportion of participants in the iGlarLixi (fixed-ratio combination of insulin glargine and lixisenatide) vs. insulin glargine alone or lixisenatide alone treatment arms achieved HbA_1c goals (P < 0.001 for overall comparisons), irrespective of ADA- or AACE-defined targets. Hypoglycaemia rates [any, documented symptomatic (plasma glucose ≤ 3.9 mmol/l), and clinically important (plasma glucose < 3.0 mmol/l)] were low across all groups. Participants treated with iGlarLixi tended to show weight loss or less weight gain compared with participants receiving insulin glargine alone. No differences were observed in average daily basal insulin dose at week 30 between the two treatment arms or across the different FPG and PPG target groups.

CONCLUSION

Insulin glargine and lixisenatide as a fixed-ratio combination resulted in more participants reaching both FPG and PPG targets, leading to better HbA_1c target attainment.

The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances

The purpose of this review is to provide an overview of diets, food, and food components that affect postprandial inflammation, endothelial function, and oxidative stress, which are related to cardiometabolic risk. A high-energy meal, rich in saturated fat and sugars, induces the transient appearance of a series of metabolic, signaling and physiological dysregulations or dysfunctions, including oxidative stress, low-grade inflammation, and endothelial dysfunction, which are directly related to the amplitude of postprandial plasma triglycerides and glucose. Low-grade inflammation and endothelial dysfunction are also known to cluster together with insulin resistance, a third risk factor for cardiovascular diseases (CVD) and type-II diabetes, thus making a considerable contribution to cardiometabolic risk. Because of the marked relevance of the postprandial model to nutritional pathophysiology, many studies have investigated whether adding various nutrients and other substances to such a challenge meal might mitigate the onset of these adverse effects. Some foods (e.g., nuts, berries, and citrus), nutrients (e.g., l-arginine), and other substances (various polyphenols) have been widely studied. Reports of favorable effects in the postprandial state have concerned plasma markers for systemic or vascular pro-inflammatory conditions, the activation of inflammatory pathways in plasma monocytes, vascular endothelial function (mostly assessed using physiological criteria), and postprandial oxidative stress. Although the literature is fragmented, this topic warrants further study using multiple endpoints and markers to investigate whether the interesting candidates identified might prevent or limit the postprandial appearance of critical features of cardiometabolic risk.

Importance of Postprandial Glucose in Relation to A1C and Cardiovascular Disease

IN BRIEF This article reviews the evidence regarding the impact of postprandial glucose (PPG) on overall A1C and its relation to cardiovascular disease (CVD). To date, four randomized, controlled trials have evaluated the impact of PPG reduction on CVD; however, only one of these successfully demonstrated a positive effect. Despite this, epidemiological evidence does indicate a cardiovascular benefit of PPG reduction, and agents that can be used to manage PPG in people with type 2 diabetes are also discussed.

Meta-analysis and critical review on the efficacy and safety of alpha-glucosidase inhibitors in Asian and non-Asian populations

AIMS/INTRODUCTION

To evaluate the efficacy and safety of alpha-glucosidase inhibitors (AGI) in Asian and non-Asian type 2 diabetes patients.

MATERIALS AND METHODS

Studies were identified through a literature search of MEDLINE, EMBASE and other databases until December 2016. All statistical analyses were carried out in Review Manager statistical software by computing the weighted mean difference or odds ratio and 95% confidence interval.

RESULTS

A total of 67 studies were included. AGI vs placebo: compared with the placebo, AGI treatment led to a greater decrease in hemoglobin A1c (HbA1c), fasting plasma glucose and postprandial plasma glucose. No significant difference was observed in HbA1c change, fasting plasma glucose change, postprandial plasma glucose change or incidence of hypoglycemia between Asian and non-Asian patients. AGI vs active controls: in Asian patients, AGI treatment showed a lower reduction in HbA1c compared with dipeptidyl peptidase-4 inhibitors and sulfonylurea. In non-Asian patients, AGI treatment showed a lower reduction in HbA1c compared with thiazolidinedione. No significant difference was observed in HbA1c change and bodyweight change when comparing AGI with other oral hypoglycemic agents between Asian and non-Asian patients.

CONCLUSIONS

The effects of AGI treatment on glycemic control and bodyweight reduction were superior to the placebo without an increased incidence of hypoglycemia, but with an increased incidence of gastrointestinal discomforts. The hypoglycemic effects of AGI were comparable between Asian and non-Asian patients.

Comparison of acarbose and metformin therapy in newly diagnosed type 2 diabetic patients with overweight and/or obesity

OBJECTIVE

To compare the efficacy of acarbose and metformin in overweight and/or obese patients with newly diagnosed type 2 diabetes mellitus (T2DM).

METHODS

A total of 108 drug-naïve patients with newly diagnosed T2DM, whose hemoglobin A1c (HbA1c) was between 7% and 10% and body mass index was greater than 24 kg/m(2), were enrolled in the First People's Hospital and Municipal Central Hospital of Xiangtan City, Xiangtan, China, from 1 February 2010 to 1 August 2011. Patients were randomly assigned to acarbose (100 mg three times a day) and metformin (1.5 g/day) groups for a predictive follow-up period of 24 weeks. Plasma glucose, insulin, and glucagons at 0, 0.5, and 2 hours after a standardized meal, and HbA1c were measured at baseline and 24 weeks.

RESULTS

Baseline characteristics of the acarbose and metformin groups were similar. Glucose control improved significantly in both groups at 24 weeks. The percentage of patients achieving HbA1C <6.5% was comparable for acarbose and metformin therapy at 24 weeks. Body weight reduction from baseline to 24 weeks was 3.3 kg in the acarbose group and 2.7 kg in the metformin group, whereas the change in HbA1c and body weight was similar in both groups. The early-phase insulin secretion index improved only in the acarbose group at 24 weeks. After 24 weeks of therapy, fasting glucagon and 0.5 hour postprandial glucagon levels decreased markedly in the acarbose group compared to the metformin group.

CONCLUSIONS

Twenty-four weeks of therapy with acarbose and metformin induced similar reductions in HbA1c and body weight, but acarbose showed superior efficacy in improving islet α-cell function compared with metformin in overweight/obese patients with newly diagnosed T2DM. However, more large-sample, multicenter, randomized controlled trials are needed to evaluate the efficacy, safety, cost-effectiveness, and glycemic variability of the two drugs.

Therapeutic potential of α-glucosidase inhibitors in type 2 diabetes mellitus: an evidence-based review

INTRODUCTION

Postprandial hyperglycemia (PPHG) contributes to micro- and macro-vascular complications more than fasting hyperglycemia in patients with type 2 diabetes mellitus. Due to the traditional carbohydrate-rich diet, Asians, particularly Indians and Chinese need agents to control the higher risk of uncontrolled PPHG. Targeting PPHG with α-glucosidase inhibitors (AGIs), either alone or in combination with other oral hypoglycemic agents and insulin, provide overall glycemic control with transient mild gastrointestinal disorders. Treatment with AGIs, especially acarbose, has also shown to provide beneficial effects on lipid levels, blood pressure, coagulation factors, carotid intima-media thickness and endothelial dysfunction. New insights of acarbose therapy obtained like increased activity of gut hormones and improved gut microbiota may explain the benefits on weight, whereas increased production of H2 may explains its cardiovascular benefits to some extent.

AREAS COVERED

A systematic search strategy was developed to identify randomized controlled trials in MEDLINE, PubMed, EMBASE and ongoing trials databases.

EXPERT OPINION

AGIs as a class and acarbose in particular, are most useful in combatting PPHG and glucose variability across the spectrum of diabetes therapy, particularly in Asian patients. Together with their effects on incretin hormones and gut-microbiota AGIs can be considered beyond glycemic control as 'cardio-protective agents.'

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.

Targeting the kidney and glucose excretion with dapagliflozin: preclinical and clinical evidence for SGLT2 inhibition as a new option for treatment of type 2 diabetes mellitus

Sodium-glucose cotransporter-2 (SGLT2) inhibitors are a novel class of glucuretic, antihyperglycemic drugs that target the process of renal glucose reabsorption and induce glucuresis independently of insulin secretion or action. In patients with type 2 diabetes mellitus, SGLT2 inhibitors have been found to consistently reduce measures of hyperglycemia, including hemoglobin A1c, fasting plasma glucose, and postprandial glucose, throughout the continuum of disease. By inducing the renal excretion of glucose and its associated calories, SGLT2 inhibitors reduce weight and have the potential to be disease modifying by addressing the caloric excess that is believed to be one of the root causes of type 2 diabetes mellitus. Additional benefits, including the possibility for combination with insulin-dependent antihyperglycemic drugs, a low potential for hypoglycemia, and the ability to reduce blood pressure, were anticipated from the novel mechanism of action and have been demonstrated in clinical studies. Mechanism-related risks include an increased incidence of urinary tract and genital infections and the possibility of over-diuresis in volume-sensitive patients. Taken together, the results of Phase III clinical studies generally point to a positive benefit-risk ratio across the continuum of diabetes patients. To date, data on dapagliflozin, a selective SGLT2 inhibitor in development, demonstrate that the kidney is an efficacious and safe target for therapy, and that SGLT2 inhibition may have benefits for patients with type 2 diabetes mellitus beyond glycemic control.

Impaired fasting glucose association with mortality in nondiabetic patients on maintenance peritoneal dialysis

INTRODUCTION

The aim of this study was to investigate clinical significance of impaired fasting glucose (IFG) in nondiabetic patients on maintenance peritoneal dialysis (PD).

METHODS

In total, 362 maintenance PD patients were enrolled and followed up for 2-years. According to 1997 definitions, patients were divided into 3 groups: diabetic (n = 85), nondiabetic with IFG (n = 62) and nondiabetic with normal fasting glucose levels (n = 215). After basal data were collected for cross-sectional analyses, mortality and cause of death were recorded for longitudinal analyses.

RESULTS

After adjusting for related variables by multivariate logistic regression analysis, IFG was found to be positively associated with age but negatively associated with normalized protein nitrogen appearance and transferrin saturation in nondiabetic maintenance PD patients. Thirty nondiabetic patients had died after the 2-year follow-up. Cox multivariate analysis showed that age (hazard ratio: 1.037; 95% confidence interval: 1.002-1.073; P = 0.036) and presence of IFG (hazard ratio: 2.719; 95% confidence interval: 1.082-6.833; P = 0.033) were significant risk factors for all-cause 2-year mortality in nondiabetic maintenance PD patients.

CONCLUSIONS

IFG, a preventable and treatable condition, was associated with all-cause 2-year mortality in nondiabetic maintenance PD patients.

dGlucose is linked to renal function changes in diabetes

AIMS

This study examines if dglucose, two-hour postprandial (2 hPP) minus fasting glucose (F), predicts glycemic control better than F or 2 hPPglucose.

METHODS

F and 2 hPPglucose, and renal function variables; BUN, serum creatinine (Scr), and estimated GFR (eGFR), were obtained from 56 insulin treated diabetic adults. 2 hPP-F(d) was calculated. Variables were compared when 2 hPPglucose was <200 (n=23) or >200 mg/dL (n=33). Correlation coefficients were calculated for F, 2 hPP or 2 hPP-F(d) renal function variables versus those for glucose.

RESULTS

Variables differed significantly between F and 2 hPP (t-test, p<0.05) for all patients and when 2 hPPglucose was < or >200 mg/dL, except dBUN at <200 mg/dL. When F, 2 hPP or 2 hPP-F(d) variables between 2 hPPglucose< and >200 mg/dL were compared, dScr was significant (p=0.0327). Correlation coefficients between dglucose and dScr or deGFR, were significant for all patients (r=0.420, p=0.0013, and r=-0.434, p=0.0008, respectively) and for 2 hPPglucose >200 mg/dL (r=0.523, p=0.0018 and r=-0.513, p=0.0023, respectively) but not 2 hPPglucose <200 mg/dL. When dglucose increased by 100 mg/dL, dScr increased by 0.08 and 0.11 mg/dL, and deGFR decreased by 2.73 and 3.73 mL/min for all patients and >200 mg/dL, respectively.

CONCLUSIONS

dGlucose better predicts renal function changes than F or 2 hPPglucose. Postprandial hyperglycemia (<200 mg/dL) control is crucial for renal protection in diabetes.

Early microvascular complications of prediabetes in mice with impaired glucose tolerance and dyslipidemia

Microvascular complications are an important cause of morbidity in diabetic patients and can be detected in a significant number of patients at the time of diabetes diagnosis. However, little is known about the alterations in the microvasculature previous to the clinical manifestation of diabetes mellitus type 2. To obtain more insights into the early microvascular deterioration resulting from prediabetes, morphological and functional microvascular parameters were monitored using intravital fluorescence microscopy through a dorsal skin-fold chamber preparation in the uncoupling promotor-driven diphtheria toxin A chain (UCP1/DTA) mice. At the age of 12 weeks, the UCP1/DTA-mice were characterized by impaired glucose tolerance with concurrent unchanged fasting glucose, as well as dyslipidemia, hyperinsulinemia, hypertension and obesity. Prediabetic mice displayed combined hypertriglyceridemia and hypercholesterinemia. Associated with these prediabetic metabolic alterations, we demonstrate that microvascular density showed a dramatic decrease due to a reduction in perfused small vessels. A reduction in vascular density combined with unaltered blood flow in single vessels resulted in impaired tissue perfusion. Endothelial dysfunction with subsequently increased microvascular permeability and leukocyte-endothelium interactions were found. Our results of profound microvascular alterations at stages of normal fasting glucose underline the importance of early screening for prediabetes and associated microvascular complications.

Efficacy and safety of vildagliptin and voglibose in Japanese patients with type 2 diabetes: a 12-week, randomized, double-blind, active-controlled study

AIM

To confirm the efficacy of vildagliptin in patients with type 2 diabetes (T2D) by testing the hypothesis that glycosylated haemoglobin (HbA1c) reduction with vildagliptin is superior to that with voglibose after 12 weeks of treatment.

METHODS

In this 12-week, randomized, double-blind, active-controlled, parallel-group study, the efficacy and safety of vildagliptin (50 mg bid, n = 188) was compared with that of voglibose (0.2 mg tid, n = 192) in patients with T2D who were inadequately controlled with diet and exercise.

RESULTS

The characteristics of two groups were well matched at baseline. The mean age, body mass index (BMI) and HbA1c were 59.1 years, 24.9 kg/m(2) and 7.6%, respectively. At baseline, fasting plasma glucose (FPG) and 2-h postprandial glucose (PPG) were 9.01 mmol/l (162.2 mg/dl) and 13.57 mmol/l (244.3 mg/dl), respectively. The adjusted mean change in HbA1c from baseline to endpoint was -0.95 +/- 0.04% in the vildagliptin-treated patients and -0.38 +/- 0.04% in those receiving voglibose (between-group change = 0.57 +/- 0.06%, 95% confidence interval (CI) (-0.68 to -0.46%), p < 0.001), showing that vildagliptin was superior to voglibose. Endpoint HbA1c < or = 6.5% was achieved in 51% vildagliptin-treated patients compared with 24% patients who were on voglibose (p < 0.001). Vildagliptin also exhibited significantly (p < 0.001) greater reduction compared with voglibose in both FPG [1.34 vs. 0.43 mmol/l (24.1 vs. 7.8 mg/dl)] and 2-h PPG [2.86 vs. 1.1 mmol/l (51.5 vs. 19.8 mg/dl)]. Overall adverse events (AEs) were lower in the vildagliptin-treated patients compared with that in the voglibose-treated patients (61.2 vs. 71.4%), with no incidence of hypoglycaemia and serious adverse events with vildagliptin. Gastrointestinal AEs were significantly lower with vildagliptin compared with that of the voglibose (18.6 vs. 32.8%; p = 0.002).

CONCLUSIONS

Vildagliptin (50 mg bid) showed superior efficacy and better tolerability compared with voglibose in Japanese patients with T2D.

The effects of acarbose treatment on intimal hyperplasia in a rat carotid endarterectomy model of diet-induced insulin resistance

BACKGROUND

Increased carotid restenosis due to revascularization therapy is associated with insulin resistance. We hypothesize that glucose control using acarbose may attenuate intimal hyperplasia in rat carotid endarterectomy model of diet-induced insulin resistance.

METHODS

Rats were fed low-fat complex carbohydrate (control) or high-fat sucrose (insulin resistance) for 4 months. Three days preoperatively, some high-fat-sucrose rats were on acarbose, remainder of the rats received placebo. Rat carotids were assessed with duplex pre-and postoperatively. Acarbose and placebo continued for 2 weeks. Glucose, insulin, blood flow velocities and intimal hyperplasia were determined.

RESULTS

High-fat sucrose plus acarbose attenuated intimal hyperplasia. Post-drug high-fat sucrose glucose decreased. Blood flow velocities postoperatively elevated above baseline. High-fat sucrose increased blood flow velocities postoperatively, which was attenuated with acarbose.

CONCLUSION

Glucose control by acarbose in rat carotid endarterectomy model of diet-induced insulin resistance resulted in attenuation of intimal hyperplasia.

Soya protein does not affect glycaemic control in adults with type 2 diabetes

Evidence from observational, animal and human studies supports a role for soya protein and its isoflavones in the improvement of glycaemic control in type 2 diabetes. The objective of the present study was to determine the effect of isoflavone-rich soya protein on markers of glycaemic control in adults with type 2 diabetes. Using a randomised, crossover, double-blind, placebo-controlled design, adults with diet-controlled type 2 diabetes (n 29) consumed soya protein isolate (SPI) and milk protein isolate (MPI) for 57 d each separated by a 4-week washout. Blood was collected on days 1 and 57 of each treatment period for analysis of fasting HbA1C, and fasting and postprandial glucose, insulin and calculated indices of insulin sensitivity and resistance. Urine samples of 24 h were collected at the end of each treatment period for analysis of isoflavones. Urinary isoflavone excretion was significantly greater following consumption of SPI compared with MPI, and 20.7 % of the subjects (n 6) were classified as equol excretors. SPI consumption did not significantly affect fasting or postprandial glucose or insulin, fasting HbA1C, or indices of insulin sensitivity and resistance. These data do not support a role for soya protein in the improvement of glycaemic control in adults with diet-controlled type 2 diabetes and contribute to a limited literature of human studies on the effects of soya protein on the management of type 2 diabetes.

Animal models of catheter-induced intimal hyperplasia in type 1 and type 2 diabetes and the effects of pharmacologic intervention

Diabetes is a complex disorder characterized by impaired insulin formation, release or action (insulin resistance), elevated blood glucose, and multiple long-term complications. It is a common endocrine disorder of humans and is associated with abnormalities of carbohydrate and lipid metabolism. There are two forms of diabetes, classified as type 1 and type 2. In type 1 diabetes, hyperglycemia is due to an absolute lack of insulin, whereas in type 2 diabetes, hyperglycemia is due to a relative lack of insulin and insulin resistance. More than 90% of people with diabetes have type 2 with varied degrees of insulin resistance. Insulin resistance is often associated with impaired insulin secretion, and hyperglycemia is a common feature in both types of diabetes, but failure to make a distinction between the types of diabetes in different animal models has led to confusion in the literature. This is particularly true in relation to cardiovascular disease in the presence of diabetes and especially the response to vascular injury, in which there are major differences between the two types of diabetes. Animal models do not completely mimic the clinical disease seen in humans. Animal models are at best analogies of the pathologic process they are designed to represent. The focus of this review is an analysis of intimal hyperplasia following catheter-induced vascular injury, including factors that may complicate comparisons between different animal models or between in vitro and in vivo studies. We examine the variables, pitfalls, and caveats that follow from the manner of induction of the injury and the diabetic state of the animal. The efficacy of selected antidiabetic drugs in inhibiting the development of the hyperplastic response is also discussed.

Hyperglycemia induces apoptosis of human pancreatic islet endothelial cells: effects of pravastatin on the Akt survival pathway

Pancreatic islet microendothelium and beta cells exhibit an interdependent physical and functional relationship. In this study, we analyzed the effect of chronic hyperglycemia on human pancreatic islet microendothelial cells as well as the involvement of the phosphatidylinositol 3-kinase/Akt and nephrin pathways, interleukin-1beta, and nitric oxide production. In addition, whether 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors can reverse the response to high-glucose conditions was investigated. Proliferation of purified islet microendothelial cells cultured under hyperglycemic conditions (28 mmol/L glucose) decreased compared to that of normoglycemic cells (from 12.7% after 2 days to 47.7% after 30 days, P < 0.05). In parallel, apoptosis progressively increased from 7% after 2 days to 79% after 30 days in high glucose (P < 0.05) concomitant with an early increase of caspase-3 activity. Intermittent hyperglycemia induced greater apoptosis than sustained hyperglycemia. Apoptosis was accompanied by a reduced p-Akt/Akt ratio and inhibition of nephrin tyrosine phosphorylation. Pravastatin (1 mumol/L) decreased apoptosis induced by high glucose or oxidized LDL and increased Akt phosphorylation. Hyperglycemia significantly increased the production of the proinflammatory cytokine interleukin-1beta and stimulated the expression of inducible nitric oxide synthase and the production of nitric oxide, possibly relevant to beta cell mass and function. Thus, chronic hyperglycemia reduces islet microendothelial cell survival by inhibiting the serine-threonine kinase Akt pathway, and the effect of pravastatin on this pathway represents a potential tool to improve islet vascularization and, indirectly, islet function.

Effect of cereal test breakfasts differing in glycemic index and content of indigestible carbohydrates on daylong glucose tolerance in healthy subjects

BACKGROUND

Frequent hyperglycemic episodes are increasingly being associated with an increased risk of type 2 diabetes and cardiovascular disease.

OBJECTIVE

We studied the extent to which acute glycemia and glycemia after subsequent meals can be modulated by the characteristics of cereal foods, such as glycemic index (GI) and content of indigestible carbohydrates.

DESIGN

Twelve healthy subjects consumed test meals in a random order. In series 1, the test meals were consumed at breakfast, and postprandial blood glucose incremental areas under the curve (IAUCs) were calculated after the test breakfast, standardized lunch, and standardized dinner. In series 2, the subjects consumed test evening meals and IAUCs were calculated after a subsequent standardized breakfast. Breath hydrogen was measured as an indicator of colonic fermentation.

RESULTS

Barley or rye kernel breakfasts lowered the blood glucose IAUC (0-120 min) at breakfast, at a subsequent lunch, and the cumulative IAUCs (breakfast+lunch+dinner) when compared with white-wheat bread (P < 0.05). The lunch blood glucose IAUCs were positively correlated with breakfast IAUCs (r = 0.30, P < 0.05). Breath hydrogen excretion was negatively correlated with blood glucose IAUCs after lunch (r = -0.33, P < 0.05) and dinner (r = -0.22, P < 0.05). A barley kernel evening meal resulted in lower IAUCs (P < 0.05) and higher breath hydrogen (P < 0.001) after a subsequent breakfast compared with white-wheat bread.

CONCLUSIONS

Glucose tolerance at subsequent meals can be notably improved during the course of a whole day or overnight by choosing specific low-GI, whole-grain cereal products. A low GI may be sufficient to achieve a second-meal effect from breakfast to lunch. A specific indigestible carbohydrate mixture appears to be required to show benefits on glucose tolerance in a longer time frame (9.5 h), most likely mediated through colonic fermentation.

Fasting glucose levels in predicting 1-year all-cause mortality in patients who do not have diabetes and are on maintenance hemodialysis

Chronic inflammation and malnutrition relate to increased risks for cardiovascular death. This study compared fasting glucose levels (FGL) and impaired fasting glucose (IFG) with malnutrition and inflammation in nondiabetic maintenance hemodialysis (MHD) patients to investigate the adverse affects and risks for mortality. In total, 693 MHD patients were enrolled in this study and followed up for 1 yr. Geographic, hematologic, biochemical, and dialysis-related data were collected. According to 1997 and 2003 definitions, all patients were classified into three groups: Diabetic, nondiabetic with IFG, and nondiabetic with normal FGL. More diabetic and nondiabetic with IFG group patients were malnourished (chi(2) = 24.55, P < 0.0001) and had inflammatory changes (chi(2) = 9.32, P = 0.0095) than those with normal FGL. The IFG group had higher high-sensitivity C-reactive protein and ferritin and lower serum albumin, creatinine levels, and normalized protein catabolic rate than the normal FGL group. Age and parameters of nutrition and inflammation were associated with FGL. Stepwise multiple regression analysis demonstrated that FGL were negatively associated with serum albumin (P = 0.0026) and positively correlated with Log high-sensitivity C-reactive protein (P = 0.0004) in nondiabetic MHD patients. In addition, after 1 yr of follow-up, Cox multivariate analysis demonstrated that, after adjustment for other significant related factors, FGL (relative risk 1.049; 95% confidence interval 1.007 to 1.093; P = 0.0232) or presence of IFG (relative risk 3.798; 95% confidence interval 1.168 to 12.344; P = 0.0265) was a significant risk factor for 1-yr all-cause mortality of these patients. On the basis of these findings, basal FGL or presence of IFG, a preventive and treatable status, plays an important role in inflammation, malnutrition, and short-term mortality of nondiabetic MHD patients.