Effect of acarbose on postprandial lipid metabolism in type 2 diabetes mellitus

Suppression of the postprandial hyperglycemia in patients with type 2 diabetes by a raw medicinal herb powder is weakened when consumed in ordinary hard gelatin capsules: A randomized crossover clinical trial

INTRODUCTION

Contradictory claims about the efficacy of several medicinal plants to promote glycemic control in patients with type 2 diabetes mellitus (T2DM) have been explained by divergences in the administration form and by extrapolation of data obtained from healthy individuals. It is not known whether the antidiabetic effects of traditional herbal medicines are influenced by gelatin capsules. This randomized crossover trial aimed to evaluate the acute effect of a single dose of raw cinnamon consumed orally either dissolved in water as a beverage or as ordinary hard gelatin capsules on postprandial hyperglycemia (>140 mg/dL; >7.8 mmol/L) in T2DM patients elicited by a nutritionally-balanced meal providing 50 g of complex carbohydrates.

METHODS

Fasting T2DM patients (n = 19) randomly ingested a standardized meal in five experimental sessions, one alone (Control) and the other after prior intake of 3 or 6 g of crude cinnamon in the form of hard gelatin capsules or powder dissolved in water. Blood glucose was measured at fasting and at 0.25, 0.5, 0.75, 1, 1.5 and 2 hours postprandially. After each breakfast, its palatability scores for visual appeal, smell and pleasantness of taste were assessed, as well as the taste intensity sweetness, saltiness, bitterness, sourness and creaminess.

RESULTS

The intake of raw cinnamon dissolved in water, independently of the dose, decreased the meal-induced large glucose spike (peak-rise of +87 mg/dL and Δ1-hour glycemia of +79 mg/dL) and the hyperglycemic blood glucose peak. When cinnamon was taken as capsules, these anti-hyperglycemic effects were lost or significantly diminished. Raw cinnamon intake did not change time-to-peak or the 2-h post-meal glycaemia, but flattened the glycemic curve (lower iAUC) without changing the shape that is typical of T2DM patients.

CONCLUSIONS

This cinnamon's antihyperglycemic action confirms its acarbose-like property to inhibit the activities of the carbohydrate-digesting enzymes α-amylases/α-glucosidases, which is in accordance with its exceptionally high content of raw insoluble fiber. The efficacy of using raw cinnamon as a diabetes treatment strategy seems to require its intake at a specific time before/concomitantly the main hyperglycemic daily meals. Trial registration: Registro Brasileiro de Ensaios Clínicos (ReBEC), number RBR-98tx28b.

The effect of acarbose on lipid profiles in adults: a systematic review and meta-analysis of randomized clinical trials

PURPOSE

Dyslipidemia, characterized by elevated levels of triglycerides (TG), low-density lipoprotein (LDL), total cholesterol (TC), and reduced levels of high-density lipoprotein (HDL), is a major risk factor for cardiovascular diseases (CVD). Several studies have shown the potential of acarbose in improving serum lipid markers. However, there have been conflicting results on the topic in adults. Therefore, a comprehensive systematic review and meta-analysis was conducted to assess the impact of acarbose on lipid profiles.

METHODS

The random-effects approach was used to combine the data, and the results were provided as weighted mean difference (WMD) with 95% confidence intervals (CI).

RESULTS

Our meta-analysis included a total of 74 studies with a combined sample size of 7046 participants. The results of the analysis showed that acarbose resulted in a reduction in levels of TG (WMD = - 13.43 mg/dl, 95% CI: - 19.20, - 7.67; P < 0.001) and TC (WMD = - 1.93 mg/dl, 95% CI: - 3.71, - 0.15; P = 0.033), but did not affect other lipid markers. When conducting a nonlinear dose-response analysis, we found that acarbose was associated with an increase in levels of HDL (coefficients = 0.50, P = 0.012), with the highest increase observed at a dosage of 400 mg/d. Furthermore, our findings suggested a non-linear relationship between the duration of the intervention and TC (coefficients = - 18.00, P = 0.032), with a decline observed after 50 weeks of treatment.

CONCLUSION

The findings of this study suggest that acarbose can reduce serum levels of TG and TC. However, no significant effects were observed on LDL or HDL levels.

Postprandial Hyperlipidemia: Its Pathophysiology, Diagnosis, Atherogenesis, and Treatments

Postprandial hyperlipidemia showing postprandial increases in serum triglyceride (TG) is associated with the development of atherosclerotic cardiovascular disease (ASCVD). To diagnose postprandial hyperlipidemia, the oral fat loading test (OFLT) should be performed; however, this test is very time-consuming and is difficult to perform. Elevated serum TG levels reflect an increase in TG-rich lipoproteins (TRLs), such as chylomicrons (CM), very low-density lipoproteins (VLDL), and their remnants (CM remnants [CMRs] and VLDL remnants [VLDLRs]). Understanding of elevation in CMR and/or VLDLR can lead us to understand the existence of postprandial hyperlipidemia. The measurement of apo B48, which is a constituent of CM and CMR; non-fasting TG, which includes TG content in all lipoproteins including CM and CMR; non-high-density lipoprotein cholesterol (non-HDL-C), which includes TRLs and low-density lipoprotein; and remnant cholesterol are useful to reveal the existence of postprandial hyperlipidemia. Postprandial hyperlipidemia is observed in patients with familial type III hyperlipoproteinemia, familial combined hyperlipidemia, chronic kidney disease, metabolic syndrome and type 2 diabetes. Postprandial hyperlipidemia is closely related to postprandial hyperglycemia, and insulin resistance may be an inducing and enhancing factor for both postprandial hyperlipidemia and postprandial hyperglycemia. Remnant lipoproteins and metabolic disorders associated with postprandial hyperlipidemia have various atherogenic properties such as induction of inflammation and endothelial dysfunction. A healthy diet, calorie restriction, weight loss, and exercise positively impact postprandial hyperlipidemia. Anti-hyperlipidemic drugs such pemafibrate, fenofibrate, bezafibrate, ezetimibe, and eicosapentaenoic acid have been shown to improve postprandial hyperlipidemia. Anti-diabetic drugs including metformin, alpha-glucosidase inhibitors, pioglitazone, dipeptidyl-peptidase-4 inhibitors and glucagon-like peptide 1 analogues have been shown to ameliorate postprandial hyperlipidemia. Although sodium glucose cotransporter-2 inhibitors have not been proven to reduce postprandial hyperlipidemia, they reduced fasting apo B48 and remnant lipoprotein cholesterol. In conclusion, it is important to appropriately understand the existence of postprandial hyperlipidemia and to connect it to optimal treatments. However, there are some problems with the diagnosis for postprandial hyperlipidemia. Postprandial hyperlipidemia cannot be specifically defined by measures such as TG levels 2 h after a meal. To study interventions for postprandial hyperlipidemia with the outcome of preventing the onset of ASCVD, it is necessary to define postprandial hyperlipidemia using reference values such as IGT.

Acute Flaxseed Intake Reduces Postprandial Glycemia in Subjects with Type 2 Diabetes: A Randomized Crossover Clinical Trial

Background: Postprandial glycemic excursions are associated with impairment control of diabetes mellitus. Long-term consumption of flaxseed can lower blood glucose levels; however, its effects on the postprandial glycemic response remain unknown. Therefore, this study aimed to evaluate the acute effects of raw flaxseed consumption on the 2 h postprandial glycemic curve in men with type 2 diabetes mellitus (T2DM). Methods: This was a randomized crossover clinical trial. Nineteen men with T2DM were randomly assigned a standardized breakfast without (control) or with a previous intake of 15 g of ground raw golden flaxseed (flax). Glycemia was measured at fasting and postprandial at 15, 30, 45, 60, 90, and 120 min. Palatability markers (visual appeal, smell, and pleasantness of taste) and taste intensity (sweetness, saltiness, bitterness, sourness, and creaminess) were evaluated. Results: The peak glucose rise and the 2 h AUC glycemic response reduced in the flax group by 17% (p = 0.001) and 24% (p < 0.001), respectively. The glucose peak time, palatability, and taste parameters did not differ between the two groups. Conclusions: Ingestion of 15 g of ground raw golden flaxseed before breakfast decreases the 2 h postprandial glycemic response in men with T2DM.

Could consumption of yam (Dioscorea) or its extract be beneficial in controlling glycaemia: a systematic review

Yam (Dioscorea spp.) and its associated extracts have been shown to possess a variety of biological activities and identified as beneficial in the control of glycaemia in patients with type II diabetes mellitus (T2DM). The objective was to conduct a systematic search of the literature to investigate whether yam and its extract can improve glycaemia and whether the consumption of yam could be beneficial for managing T2DM. Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and the Population, Invention, Comparison and Outcome framework, three databases (PubMed, Scopus and Web of Science) were searched using a key term strategy. Strict inclusion criteria were employed to identify all relevant and available studies. The quality of these studies was assessed using SYRCLE's Risk of Bias tool. Ten studies were included, and all studies consisted of findings from rodent models of diabetes, including animals consuming high fat diets or genetic models of diabetes. All ten studies showed that the consumption of yam and/or its extracts (containing dioscin, dioscorin, diosgenin, DA-9801/02 or Chinese yam polysaccharides) improved glycaemia. These included improvements in fasting blood glucose and reductions in glucose and increase in insulin levels following a glucose tolerance test. Furthermore, significant changes in body weight and adiposity were observed in nine studies, these included improvements in lipid biomarkers in four and reductions in inflammatory markers in one. The current work indicates that the consumption of yam or its extracts can be beneficial for improving blood glucose; however, the molecular mechanism for these effects remains largely unknown. Future trials on human subjects are warranted.

Loss of Sucrase-Isomaltase Function Increases Acetate Levels and Improves Metabolic Health in Greenlandic Cohorts

BACKGROUND & AIMS

The sucrase-isomaltase (SI) c.273_274delAG loss-of-function variant is common in Arctic populations and causes congenital sucrase-isomaltase deficiency, which is an inability to break down and absorb sucrose and isomaltose. Children with this condition experience gastrointestinal symptoms when dietary sucrose is introduced. We aimed to describe the health of adults with sucrase-isomaltase deficiency.

METHODS

The association between c.273_274delAG and phenotypes related to metabolic health was assessed in 2 cohorts of Greenlandic adults (n = 4922 and n = 1629). A sucrase-isomaltase knockout (Sis-KO) mouse model was used to further elucidate the findings.

RESULTS

Homozygous carriers of the variant had a markedly healthier metabolic profile than the remaining population, including lower body mass index (β [standard error], -2.0 [0.5] kg/m²; P = 3.1 × 10^-5), body weight (-4.8 [1.4] kg; P = 5.1 × 10^-4), fat percentage (-3.3% [1.0%]; P = 3.7 × 10^-4), fasting triglyceride (-0.27 [0.07] mmol/L; P = 2.3 × 10^-6), and remnant cholesterol (-0.11 [0.03] mmol/L; P = 4.2 × 10^-5). Further analyses suggested that this was likely mediated partly by higher circulating levels of acetate observed in homozygous carriers (β [standard error], 0.056 [0.002] mmol/L; P = 2.1 × 10^-26), and partly by reduced sucrose uptake, but not lower caloric intake. These findings were verified in Sis-KO mice, which, compared with wild-type mice, were leaner on a sucrose-containing diet, despite similar caloric intake, had significantly higher plasma acetate levels in response to a sucrose gavage, and had lower plasma glucose level in response to a sucrose-tolerance test.

CONCLUSIONS

These results suggest that sucrase-isomaltase constitutes a promising drug target for improvement of metabolic health, and that the health benefits are mediated by reduced dietary sucrose uptake and possibly also by higher levels of circulating acetate.

Gene Cascade Shift and Pathway Enrichment in Rat Kidney Induced by Acarbose Through Comparative Analysis

Acarbose is an effective anti-diabetic drug to treat type 2 diabetes mellitus (T2DM), a chronic degenerative metabolic disease caused by insulin resistance. The beneficial effects of acarbose on blood sugar control in T2DM patients have been confirmed by many studies. However, the effect of acarbose on patient kidney has yet to be fully elucidated. In this study, we report in detail the gene expression cascade shift, pathway and module enrichment, and interrelation network in acarbose-treated Rattus norvegicus kidneys based on the in-depth analysis of the GSE59913 microarray dataset. The significantly differentially expressed genes (DEGs) in the kidneys of acarbose-treated rats were initially screened out by comparative analysis. The enriched pathways for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were further identified. The protein-protein interaction (PPI) analysis for DEGs was achieved through the STRING database mining. Pathway interrelation and hub genes for enriched pathways were further examined to uncover key biological effects of acarbose. Results revealed 44 significantly up-regulated genes and 86 significantly down-regulated genes (130 significant differential genes in total) in acarbose-treated rat kidneys. Lipid metabolism pathways were considerably improved by acarbose, and the physical conditions in chronic kidney disease (CKD) patients were improved possibly through the increase of the level of high-density lipoprotein (HDL) by lecithin-cholesterol acyl-transferase (LCAT). These findings suggested that acarbose may serve as an ideal drug for CKD patients, since it not only protects the kidney, but also may relieve the complications caused by CKD.

Acarbose has sex-dependent and -independent effects on age-related physical function, cardiac health, and lipid biology

With an expanding aging population burdened with comorbidities, there is considerable interest in treatments that optimize health in later life. Acarbose (ACA), a drug used clinically to treat type 2 diabetes mellitus (T2DM), can extend mouse life span with greater effect in males than in females. Using a genetically heterogeneous mouse model, we tested the ability of ACA to ameliorate functional, pathological, and biochemical changes that occur during aging, and we determined which of the effects of age and drug were sex dependent. In both sexes, ACA prevented age-dependent loss of body mass, in addition to improving balance/coordination on an accelerating rotarod, rotarod endurance, and grip strength test. Age-related cardiac hypertrophy was seen only in male mice, and this male-specific aging effect was attenuated by ACA. ACA-sensitive cardiac changes were associated with reduced activation of cardiac growth-promoting pathways and increased abundance of peroxisomal proteins involved in lipid metabolism. ACA further ameliorated age-associated changes in cardiac lipid species, particularly lysophospholipids - changes that have previously been associated with aging, cardiac dysfunction, and cardiovascular disease in humans. In the liver, ACA had pronounced effects on lipid handling in both sexes, reducing hepatic lipidosis during aging and shifting the liver lipidome in adulthood, particularly favoring reduced triglyceride (TAG) accumulation. Our results demonstrate that ACA, already in clinical use for T2DM, has broad-ranging antiaging effects in multiple tissues, and it may have the potential to increase physical function and alter lipid biology to preserve or improve health at older ages.

Considerations when using alpha-glucosidase inhibitors in the treatment of type 2 diabetes

Introduction: Alpha-glucosidase inhibitors (AGIs) - oral antihyperglycemic drugs, inhibit upper gastrointestinal enzymes that break down complex carbohydrates into glucose. As a result, the absorption of glucose is delayed, postprandial glucose reduced, and glycemic control improved.Areas covered: In this review, the authors describe the current recommendations on the use of the three major approved AGIs (acarbose, miglitol, voglibose). Efficacy and safety parameters together with ethnic considerations have been highlighted throughout the manuscript. The article also discusses potential diabetes prevention and cardiovascular effects of these medications.Expert opinion: The overall safety and efficacy of this class of drug appears to be high: AGIs do not increase the risk of hypoglycemia, do not cause weight gain; they also significantly improve postprandial hyperglycemia, have been associated with the reduction in risk factors for cardiovascular disease and may also delay the progression of prediabetes to T2DM. In general, we continue to believe that acarbose, miglitol, and voglibose should be used as third-line add on treatment options to other anti-hyperglycemic agents. However, this class can have earlier consideration in elderly and/or when metformin is contraindicated.

Treatment Strategy for Type 2 Diabetes with Obesity: Focus on Glucagon-like Peptide-1 Receptor Agonists

PURPOSE

The progressive nature of type 2 diabetes mellitus (T2DM) calls for step-wise intensification of therapy for maintaining normal glycemic levels and lowering cardiovascular (CV) risk. Because obesity is a prominent risk factor and comorbidity of T2DM, it further elevates the CV risk in T2DM. Therefore, it is vital to manage weight, obesity, and glycemic parameters for effective T2DM management. Few oral antidiabetic drugs (sulfonylureas and thiazolidinediones) and insulin are not suitable for obese patients with T2DM because these drugs cause weight gain. The present review discusses the place of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of obese patients with T2DM and the significance of these drugs in the prevention of future CV risk in patients with T2DM.

METHODS

A literature search of PubMed and EMBASE was conducted by using the search terms T2DM, GLP-1RAs, obesity, and cardiovascular complication. Randomized controlled trials measuring the effect of GLP-1RAs versus that of placebo on CV outcomes were included in the review.

FINDINGS

GLP-1RAs have emerged as a therapeutic alternative; these drugs exert their actions by providing glycemic control, improving insulin resistance and ö̇-cell function, and reducing weight. The risk of hypoglycemia with GLP-1RAs is minimal; however, GLP-1RAs are associated with gastrointestinal adverse events and raise concerns regarding pancreatitis. Combining GLP-1RAs with insulin analogues results in higher efficacy, a lowered insulin dose, and reduced insulin-related hypoglycemia and weight gain. Longer acting GLP-1RAs are also associated with improvement in medication adherence. Improvement in CV risk factors such as blood pressure and lipid profile further increases their usability for improving CV outcomes.

IMPLICATIONS

Overall, the properties of GLP-1RAs make them suitable for combination with oral antidiabetic drugs in the early stages of T2DM and with insulins in the later stages for optimizing comprehensive management of the disease.

Extracts of Coreopsis tinctoria Nutt. Flower Exhibit Antidiabetic Effects via the Inhibition of α-Glucosidase Activity

The aim of this study was to assay the effects of Coreopsis tinctoria Nutt. flower extracts on hyperglycemia of diet-induced obese mice and the underlying mechanisms. Coreopsis tinctoria flower was extracted with ethanol and water, respectively. The total phenol, flavonoid levels, and the constituents of the extracts were measured. For the animal experiments, C57BL/6 mice were fed with a chow diet, high-fat diet, or high-fat diet mixed with 0.4% (w/w) water and ethanol extracts of Coreopsis tinctoria flower for 8 weeks. The inhibitory effects of the extracts on α-glucosidase activity and the antioxidant properties were assayed in vitro. We found that the extracts blocked the increase of fasting blood glucose, serum triglyceride (TG), insulin, leptin, and liver lipid levels and prevented the development of glucose tolerance impairment and insulin resistance in the C57BL/6 mice induced by a high-fat diet. The extracts inhibited α-glycosidase activity and increased oxidant activity in vitro. In conclusion, Coreopsis tinctoria flower extracts may ameliorate high-fat diet-induced hyperglycemia and insulin resistance. The underling mechanism may be via the inhibition of α-glucosidase activity. Our data indicate that Coreopsis tinctoria flower could be used as a beverage supplement and a potential source of drugs for treatment of diabetics.

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.'

Acarbose: safe and effective for lowering postprandial hyperglycaemia and improving cardiovascular outcomes

α-Glucosidase inhibitors (AGIs) are a class of oral glucose-lowering drugs used exclusively for treatment or prevention of type 2 diabetes mellitus. AGIs act by altering the intestinal absorption of carbohydrates through inhibition of their conversion into simple sugars (monosaccharides) and thus decrease the bioavailability of carbohydrates in the body, significantly lowering blood glucose levels. The three AGIs used in clinical practice are acarbose, voglibose and miglitol. This review will focus on the cardiovascular properties of acarbose. The current available data suggest that AGIs (particularly acarbose) may be safe and effective for the treatment of prediabetes and diabetes.

Impact of glucose-lowering drugs on cardiovascular disease in type 2 diabetes

Type 2 diabetes mellitus (T2DM) is characterized by multiple pathophysiologic abnormalities. With time, multiple glucose-lowering medications are commonly required to reduce and maintain plasma glucose concentrations within the normal range. Type 2 diabetes mellitus individuals also are at a very high risk for microvascular complications and the incidence of heart attack and stroke is increased two- to three-fold compared with non-diabetic individuals. Therefore, when selecting medications to normalize glucose levels in T2DM patients, it is important that the agent not aggravate, and ideally even improve, cardiovascular risk factors (CVRFs) and reduce cardiovascular morbidity and mortality. In this review, we examine the effect of oral (metformin, sulfonylureas, meglitinides, thiazolidinediones, DPP4 inhibitors, SGLT2 inhibitors, and α-glucosidase inhibitors) and injectable (glucagon-like peptide-1 receptor agonists and insulin) glucose-lowering drugs on established CVRFs and long-term studies of cardiovascular outcomes. Firm evidence that in T2DM cardiovascular disease can be reversed or prevented by improving glycaemic control is still incomplete and must await large, long-term clinical trials in patients at low risk using modern treatment strategies, i.e., drug combinations designed to maximize HbA1c reduction while minimizing hypoglycaemia and excessive weight gain.

Differential therapeutic effects of nateglinide and acarbose on fasting and postprandial lipid profiles: a randomized trial

BACKGROUND

Dyslipidemia is commonly seen in patients with type 2 diabetes mellitus (T2DM). The current study sought to compare the effects of nateglinide and acarbose, two antihyperglycemic agents, on both fasting and postprandial lipid profiles in Chinese subjects with T2DM.

SUBJECTS AND METHODS

For this multicenter, open-label, randomized, active-controlled, parallel-group study, 103 antihyperglycemic agent-naive patients with T2DM were recruited from four hospitals in China. In total, 85 subjects (44 in the nateglinide group, 41 in the acarbose group) with a known complete lipid profile underwent the entire clinical trial and were included in the final analysis. Serum was collected in the fasting state and 30 and 120 min after a standardized meal (postprandial states) to measure the baseline lipid profiles; the same testing was performed upon completion of a 2-week course of nateglinide (120 mg three times a day) or acarbose (50 mg three times a day).

RESULTS

Fasting triglyceride (TG) levels were significantly reduced by both nateglinide and acarbose (P<0.001), with acarbose providing a significantly more robust improvement (vs. nateglinide, P=0.005). Additionally, the TG levels at both postprandial times were significantly reduced by acarbose (P<0.001 at 30 min and P=0.002 at 120 min), whereas nateglinide treatment only significantly reduced the 30-min postprandial TG (P=0.029). Neither nateglinide nor acarbose treatment had significant impact on total cholesterol, high-density lipoprotein, low-density lipoprotein, or non-high-density lipoprotein cholesterol.

CONCLUSIONS

Compared with nateglinide, acarbose has superior therapeutic efficacy for reducing fasting and postprandial TG levels in patients with T2DM.

Acarbose treatment and the risk of cardiovascular disease in type 2 diabetic patients: a nationwide seven-year follow-up study

OBJECTIVE

To investigate the potential benefits of acarbose treatment on cardiovascular disease (CVD) in patients with type 2 diabetes by using nationwide insurance claim dataset.

RESEARCH DESIGN AND METHODS

Among 644,792 newly diagnosed type 2 diabetic patients without preexisting CVD in a nationwide cohort study, 109,139 (16.9%) who had received acarbose treatment were analyzed for CVD risk. Those with CVD followed by acarbose therapy were also subjected to analysis.

RESULT

During 7 years of follow-up, 5,081 patients (4.7%) developed CVD. The crude hazard ratio (HR) and adjusted HR were 0.66 and 0.99, respectively. The adjusted HR of CVD was 1.19, 0.70, and 0.38 when the duration of acarbose use was <12 months, 12-24 months, and >24 months, respectively. Adjusted HR was 1.14, 0.64, and 0.41 with acarbose cumulative doses <54,750 mg, 54,751 to 109,500 mg, and >109,500 mg, respectively.

CONCLUSION

In patients with type 2 diabetes without preexisting CVD, treatment with acarbose showed a transient increase in incidence of CVD in the initial 12 months followed by significant reductions of CVD in prolonged acarbose users. After the first CVD events, continuous use of acarbose revealed neutral effect within the first 12 months. The underlying mechanisms require further investigations.

On the potential of acarbose to reduce cardiovascular disease

In the emerging landscape of cardiovascular (CV) outcome trials evaluating the effects of blood glucose lowering drugs in individuals with type 2 diabetes, it is becoming increasingly apparent that since the promising signals coming from the United Kingdom Prospective Diabetes Study (UKPDS) no unequivocal benefits have been established for any single therapy thus far. There is an unmet need for introducing an effective pharmacological agent which could target both correlates of glycaemic regulation and CV risk factors, to ameliorate the enormous burden of fatal and non-fatal CV events in diabetic patients. Acarbose, like other alpha-glucosidase inhibitors (AGIs), has been proven to be an effective antidiabetic treatment for decades, but the overall significant impact of this class of drugs on modulating CV risk has only recently been appreciated. Accumulating evidence has shown that apart from its multiple effects on primarily postprandial glucose dysmetabolism, a key component of mechanisms linked to increased incidence of CV events, acarbose therapy also associates with a favorable impact on an array of surrogate markers of CV disease. Data stemming from in vitro testing of human cell lines as well as from preliminary trials in diabetic populations, like the Study to Prevent Non-Insulin-Dependent Diabetes Mellitus (STOP-NIDDM) trial, have highlighted – though not undisputed – the potential beneficial effects of the drug on CV morbidity. Large scale trials, like the ongoing Acarbose Cardiovascular Evaluation (ACE) trial, aim at conclusively establishing such a positive effect in patients with coronary heart disease and impaired glucose tolerance. In view of its usually acceptable level of side effects that are, if they occur, mostly limited to transient gastrointestinal symptoms, acarbose could well be a strong future player in CV disease secondary prevention. Current discouraging results from many trials of antidiabetic medications to significantly lower CV event rates in diabetic patients, should only draw further attention on alternative glucose lowering agents, among which acarbose is indeed promising.

Comparison of three α-glucosidase inhibitors for glycemic control and bodyweight reduction in Japanese patients with obese type 2 diabetes

AIMS/INTRODUCTION

α-Glucosidase inhibitors (αGIs) are widely used for the primary treatment of type 2 diabetes. We compared the clinical effects of three αGIs (miglitol, acarbose and voglibose) in patients with obese type 2 diabetes.

MATERIALS AND METHODS

Japanese patients (n = 81) with obese type 2 diabetes (body mass index [BMI] ≥25 kg/m(2)) were enrolled in this multicenter, open-label study. The participants were randomized into the miglitol (n = 18), acarbose (n = 22), voglibose (n = 19) or control (n = 22) groups. Glycemic control (fasting blood glucose and glycated hemoglobin [HbA1c]), bodyweight, BMI, serum insulin, serum lipids (low-density lipoprotein and high-density lipoprotein cholesterol, and triacylglycerols) and adipocytokines (leptin and adiponectin) were evaluated every 4 weeks for 12 weeks.

RESULTS

In the miglitol group, HbA1c was improved significantly from the baseline at all points. The changes in HbA1c at 8 and 12 weeks from baseline were greater in the miglitol group than the control group. The voglibose group showed significant improvements in HbA1c at 12 weeks. Bodyweight and BMI were decreased significantly in the miglitol group. In addition, significant correlations were observed between the decrements in HbA1c and bodyweights over 12 weeks in the miglitol (r = 0.759, P < 0.001) and voglibose groups (r = 0.667, P = 0.002). Serum lipid and adipocytokine levels were not altered in any groups.

CONCLUSIONS

αGIs, especially miglitol, can effectively control blood glucose and bodyweight in obese type 2 diabetes. This study was registered with UMIN (no. UMIN000006465).

A review of the role of apolipoprotein C-II in lipoprotein metabolism and cardiovascular disease

The focus of this review is on the role of apolipoprotein C-II (apoC-II) in lipoprotein metabolism and the potential effects on the risk of cardiovascular disease (CVD). We searched PubMed/Scopus for articles regarding apoC-II and its role in lipoprotein metabolism and the risk of CVD. Apolipoprotein C-II is a constituent of chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein (HDL). Apolipoprotein C-II contains 3 amphipathic α-helices. The lipid-binding domain of apoC-II is located in the N-terminal, whereas the C-terminal helix of apoC-II is responsible for the interaction with lipoprotein lipase (LPL). At intermediate concentrations (approximately 4 mg/dL) and in normolipidemic subjects, apoC-II activates LPL. In contrast, both an excess and a deficiency of apoC-II are associated with reduced LPL activity and hypertriglyceridemia. Furthermore, excess apoC-II has been associated with increased triglyceride-rich particles and alterations in HDL particle distribution, factors that may increase the risk of CVD. However, there is not enough current evidence to clarify whether increased apoC-II causes hypertriglyceridemia or is an epiphenomenon reflecting hypertriglyceridemia. A number of pharmaceutical interventions, including statins, fibrates, ezetimibe, nicotinic acid, and orlistat, have been shown to reduce the increased apoC-II concentrations. An excess of apoC-II is associated with increased triglyceride-rich particles and alterations in HDL particle distribution. However, prospective trials are needed to assess if apoC-II is a CVD marker or a risk factor in high-risk patients.

Acarbose revisited for efficacy, safety and cardiovascular benefits: a key role for controlling glycemic variability

There is a growing body of evidence to illustrate the effect of postprandial hyperglycemia (PPHG) in cardiovascular disease development and as a key component of diurnal hyperglycemia. Agents such as acarbose, which has been shown to reduce 24-h glycemia and glycated hemoglobin (mainly via its effects on PPHG), may have the potential to reduce the risk of adverse cardiovascular outcomes as indicated in secondary analyses of the STOP-NIDDM trial. Although the results of the NAVIGATOR trial showed no effect of PPHG reduction on cardiovascular outcomes, acarbose has a different mode of action to nateglinide. This could lead to marked cardiovascular differences, and it is important to fully investigate this. The ongoing ACE trial will determine the effect of acarbose on a composite primary end point of cardiovascular outcomes.

Critical evaluation of the role of acarbose in the treatment of diabetes: patient considerations

The alpha-glucosidase inhibitor acarbose has been used for more than 20 years in the management of hyperglycemia. Owing to its unique mode of action in the gastrointestinal tract, its properties are very different from other antidiabetic medications. Patients on long-term treatment to control a chronic disease are not only interested in good treatment efficacy, but are also even more interested in the safety and side effects of their medications. Significant aspects of acarbose predominantly regarding safety and tolerability in the management of type 2 diabetes and prediabetes are reviewed. It is concluded that acarbose is a convenient long-term treatment option, with benefits for both type 2 diabetics and patients in a prediabetic state.

Diabetes mellitus: new drugs for a new epidemic

The prevalence of diabetes mellitus (DM) is increasing rapidly in the 21st century as a result of obesity, an ageing population, lack of exercise, and increased migration of susceptible patients. This costly and chronic disease has been likened recently to the 'Black Death' of the 14th century. Type 2 DM is the more common form and the primary aim of management is to delay the micro- and macrovascular complications by achieving good glycaemic control. This involves changes in lifestyle, such as weight loss and exercise, and drug therapy. Increased knowledge of the pathophysiology of diabetes has contributed to the development of novel treatments: glucagon-like peptide-1 (GLP-1) mimetics, dipeptidyl peptidase-4 (DPP-4) inhibitors, thiazolidinediones (TZDs), and insulin analogues. GLP-1 agonists mimic the effect of this incretin, whereas DPP-4 inhibitors prevent the inactivation of the endogenously released hormone. Both agents offer an effective alternative to the currently available hypoglycaemic drugs but further evaluation is needed to confirm their safety and clinical role. The past decade has seen the rise and fall in the use of the TZDs (glitazones), such that the only glitazone recommended is pioglitazone as a third-line treatment. The association between the use of rosiglitazone and adverse cardiac outcomes is still disputed by some authorities. The advent of new insulin analogues, fast-acting, and basal release formulations, has enabled the adoption of a basal-bolus regimen for the management of blood glucose. This regimen aims to provide a continuous, low basal insulin release between meals with bolus fast-acting insulin to limit hyperglycaemia after meals. Insulin therapy is increasingly used in type 2 DM to enhance glycaemic control. Recently, it has been suggested that the use of the basal-release insulins, particularly insulin glargine may be associated with an increased risk of cancer. Although attention is focused increasingly on newer agents in the treatment of diabetes, metformin and the sulphonylureas are still used in many patients. Metformin, in particular, remains of great value and may have novel anti-cancer properties.

Strategies for optimizing glycemic control and cardiovascular prognosis in patients with type 2 diabetes mellitus

Type 2 diabetes mellitus (DM) is a major cardiovascular (CV) risk factor and, as such, is considered a coronary artery disease risk equivalent. Although glycemic control is associated with decreased CV events epidemiologically, many prospective clinical trials have failed to conclusively demonstrate that aggressive glycemic control improves the CV prognosis of patients with type 2 DM, especially those with long-standing DM. Many therapies for type 2 DM with widely divergent mechanisms of action are available. Some of these drugs, in addition to their glucose-lowering actions, have properties that may reduce or increase CV events. Agents that lower both insulin resistance and postprandial hyperglycemia while at the same time avoiding hypoglycemia may be beneficial for CV health. This article reviews the evidence regarding the use of these agents and appropriate glycemic control targets for improving the adverse CV prognosis associated with type 2 DM. We conducted a systematic review of English articles using MEDLINE and the Cochrane Controlled Trials Register (1970-2010) using the following search terms: cardiovascular disease, randomized trials, hypoglycemia, and insulin resistance.

Effects of changeover from voglibose to acarbose on postprandial triglycerides in type 2 diabetes mellitus patients

INTRODUCTION

In this study, we examined the effects of the alpha-glucosidase inhibitors acarbose and voglibose on postprandial plasma glucose and serum triglyceride levels in patients with type 2 diabetes mellitus.

METHODS

Twenty-one Japanese patients with type 2 diabetes were enrolled in this study. Subjects had been treated with voglibose for at least 3 months. They underwent a 400 kcal balanced food meal tolerance test before and 8 weeks after the changeover from voglibose to acarbose. Subjects were divided into two groups: the first group (low-dose group; n=11) was changed over from 0.6 mg/day voglibose to 150 mg/day acarbose, and the other (high-dose group; n=10) from 0.9 mg/day voglibose to 300 mg/day acarbose.

RESULTS

The increment rate of postprandial plasma glucose ([plasma glucose 2 hours after test meal - fasting glucose]/fasting glucose) decreased from 34.7%+/-23.9% to 25.0%+/-24.6% (P=0.13) in the low-dose group, and decreased significantly from 56.1%+/-53.1% to 31.5%+/-36.0% (P=0.03) in the high-dose group after changeover. However, there were no significant changes in blood glycated hemoglobin (HbA(1c)) levels before and after changeover in either group. The increment rate of postprandial serum triglyceride (TG) ([serum TG 2 hours after test meal - fasting TG]/fasting TG) decreased significantly only in the high-dose group (52.4%+/-60.0% to 24.3%+/-16.6%) (P=0.05). No significant changes in serum high-density lipoprotein cholesterol levels were observed in either group, whereas serum low-density lipoprotein cholesterol levels decreased significantly from 3.20+/-0.25 to 2.65+/-0.18 mmol/L (P=0.04), only in the high-dose group.

CONCLUSIONS

In patients with type 2 diabetes our findings suggest that acarbose 300 mg/day is superior to voglibose 0.9 mg/day in improving postprandial hyperglycemia and hypertriglyceridemia.

Combination therapy with new targets in Type 2 diabetes: a review of available agents with a focus on pre-exercise adjustment

The current strategy for treating type 2 diabetes mellitus promotes combination therapy to address the 3 major defects in type 2 diabetes mellitus: (1) impaired peripheral glucose uptake (liver, fat, and muscle), (2) excessive hepatic glucose release (with glucagon excess), and (3) insufficient insulin secretion. Providers can prescribe medications that may have advantageous secondary effects in a patient-specific manner. Adjustment for exercise is generally necessary only with insulin and with medications that may allow insulin secretion despite decreasing glucose levels, such as sulfonylurea drugs. Recently, newer oral medications that address beta-cell dysfunction have been designed to avoid hypoglycemia and to "match" nutritional and non-nutritional needs more directly. Incorporating these agents into regimens will likely reduce hypoglycemia and therefore increase the safety and efficacy of exercise as both a treatment and cardiac monitoring strategy for patients with diabetes.

Long-term effects of exenatide therapy over 82 weeks on glycaemic control and weight in over-weight metformin-treated patients with type 2 diabetes mellitus

AIM

The ability of the incretin mimetic exenatide to improve glycaemic control and reduce body weight was assessed over 82 weeks in patients with type 2 diabetes failing to achieve glycaemic control with maximally effective doses of metformin.

METHODS

In this interim 82-week analysis, 150 (total cohort) of an eligible population of 183 patients opted to continue exenatide treatment in an uncontrolled open-label extension of a 30-week double-blind, placebo-controlled trial. Of these, 92 patients (completer cohort) achieved 82 weeks of exenatide therapy. Patients continued metformin throughout the study.

RESULTS

At the end of the placebo-controlled trial, exenatide resulted in an haemoglobin A1c (HbA1c) reduction from baseline of -1.0 +/- 0.1% (mean +/- SE) (exenatide treatment arms), with durable HbA1c reductions after 82 weeks of -1.3 +/- 0.1%. The percent of patients who achieved HbA1c < or = 7% at weeks 30 and 82 was 46 and 59% respectively. After 30 weeks, exenatide caused a reduction in weight from baseline of -3.0 +/- 0.6 kg, with a progressive reduction in weight of -5.3 +/- 0.8 kg after 82 weeks. In addition, exenatide treatment produced clinically significant improvements in cardiovascular risk factors after 82 weeks. The most frequent adverse event after 30 and 82 weeks of exenatide was nausea, which was generally of mild-or-moderate intensity. It decreased in incidence after initiation in the controlled trial and the uncontrolled open-label extension. Hypoglycaemia was rare, with no severe events.

CONCLUSION

Exenatide was generally well tolerated, producing a durable reduction in HbA1c and a progressive reduction in weight over 82 weeks in patients with type 2 diabetes failing to achieve glycaemic control with metformin.

An alpha-glucosidase inhibitor, voglibose, reduces oxidative stress markers and soluble intercellular adhesion molecule 1 in obese type 2 diabetic patients

Postprandial hyperglycemia and hyperlipidemia are considered risk factors for cardiovascular disease. This study was designed to elucidate whether improving the postprandial state by voglibose, an alpha-glucosidase inhibitor, leads to the reduction of oxidative stress markers and soluble adhesion molecules in obese type 2 diabetic patients. A total of 30 Japanese obese type 2 diabetic patients were randomly assigned and treated for 3 weeks with either diet alone (the control group) or diet plus voglibose (0.9 mg daily) (the voglibose group) (n=15 each). Analysis of the diurnal metabolic profiles revealed a significant reduction of postprandial hyperglycemia and hyperlipidemia in the voglibose group relative to the control group (P<.05), despite the similar improvement in body mass index and hemoglobin A(1c) in both groups. Voglibose also decreased significantly the plasma levels of soluble intercellular adhesion molecule 1 and urinary excretion of 8-iso-prostaglandin F(2)alpha and 8-hydroxydeoxyguanosine (P<.01) and C-reactive protein (P<.05) relative to the control group. In conclusion, this study represents the first demonstration that voglibose reduces oxidative stress generation and soluble intercellular adhesion molecule 1 in parallel with the reduction of postprandial hyperglycemia and hyperlipidemia in obese type 2 diabetic patients.

Cardiovascular benefits of acarbose in impaired glucose tolerance and type 2 diabetes

Impaired glucose metabolism is associated with an increased risk of cardiovascular events and cardiovascular-associated mortality. Postprandial hyperglycaemia is one of the earliest identifiable indicators of impaired glucose control. It contributes to the progression from impaired glucose tolerance to overt type 2 diabetes and exacerbates chronic hyperglycaemia in established diabetes. It is also an independent risk factor for cardiovascular disease in patients with impaired glucose tolerance and type 2 diabetes. Thus, an important strategy to reduce cardiovascular risk in patients with impaired glucose metabolism is to reduce postprandial glucose excursions. Acarbose, an alpha (alpha)-glucosidase inhibitor, reduces postprandial hyperglycaemia by delaying carbohydrate absorption from the small intestine. This mechanism of action provides glycaemic control without increasing insulin levels and exacerbating coexisting cardiovascular risk factors. The Study to Prevent Non-Insulin Dependent Diabetes Mellitus (STOP-NIDDM) assessed the ability of acarbose to reduce cardiovascular risk. In this study of 1429 individuals with impaired glucose tolerance, acarbose therapy reduced the risk of any cardiovascular event by 49% (P=0.03), of an acute myocardial infarction by 91% (P=0.02) and of developing hypertension by 34% (P=0.006). Furthermore, a retrospective meta-analysis of randomised studies of acarbose in type 2 diabetes patients showed that acarbose therapy reduced the risk of any cardiovascular event by 35% (P=0.006) and the risk of a myocardial infarction by 64% (P=0.012). These results suggest that acarbose is useful in reducing the risk of cardiovascular events in patients with impaired glucose metabolism.

Postmarketing Surveillance of??Acarbose Treatment in Taiwanese??Patients with Type??2??Diabetes Mellitus

OBJECTIVE

This postmarketing surveillance (PMS) study was conducted to assess the efficacy, safety and acceptance of acarbose treatment in patients with type 2 diabetes mellitus.

METHODS

Patients were recruited in this open, prospective, uncontrolled, non-randomised multicentre study by 159 physicians throughout Taiwan, following the guidelines of the Bureau of National Health Insurance (BNHI) of Taiwan. Primary efficacy parameters were changes in fasting blood glucose, postprandial blood glucose and glycosylated haemoglobin (HbA(1c)) values during treatment with acarbose.

RESULTS

The majority of the 1558 enrolled patients received acarbose 50 mg three times daily, had previously been treated with a sulphonylurea and/or biguanide, and were observed for a mean period of 13.9 weeks. Most patients (91.8%) received concomitant oral antihyperglycaemic agents. Acarbose reduced fasting blood glucose concentrations by 32.0 mg/dL and 2-hour postprandial blood glucose levels by 52.2 mg/dL. HbA(1c) was reduced by 1.0% from 9.9% to 8.9%, and bodyweight remained stable. The attending physicians assessed that acarbose was associated with 'very good' or 'good' general efficacy in 46.0% of patients, 'very good' or 'good' tolerability in 60.6% and 'very good' or 'good' patient acceptance in 63.4%. These ratings were higher for patients receiving acarbose monotherapy compared with those taking other antihyperglycaemic therapies in addition to acarbose. Only 2.0% of all patients experienced drug-related adverse events.

CONCLUSION

Acarbose treatment provides an efficacious, safe and well accepted alternative for metabolic improvement in Taiwanese patients with type 2 diabetes under daily-life treatment conditions.

Should Postprandial Hyperglycaemia in Prediabetic and Type 2 Diabetic Patients be Treated?

Numerous prospective studies support the concept of postprandial glycaemia (PPG) as a risk factor for cardiovascular diseases (CVDs) in individuals with impaired glucose tolerance (IGT). A meta-analysis has demonstrated an exponential relationship between 2-hour postchallenge glucose levels and the incidence of CVD. This relationship is stronger than those observed with fasting glycaemia or glycosylated haemoglobin (HbA(1c)), and persists after adjustment for other vascular risk factors. Although there are fewer data available for the diabetic population, those that are available also support PPG as a risk factor for CVD. Treating PPG with acarbose is associated with a reduction in cardiovascular events in both patients with IGT and diabetes mellitus. Acarbose also reduces the progression of intima-media thickness (IMT), which is a surrogate endpoint for atherosclerosis. It has been suggested that the beneficial effect could be related to an improvement in postprandial hyperglycaemia and associated atherogenic factors - oxidative stress, endothelial dysfunction and pro-coagulation factors - and to an improvement in other cardiovascular risk factors such as systolic blood pressure (by decreasing water and salt absorption), postprandial hypertriglyceridaemia and insulin resistance. Treating PPG with glinides improves IMT as well as interleukin-6 and C-reactive protein levels, while treating PPG with rapid-acting insulin analogues is also associated with improvements in endothelial dysfunction. The Kumamoto study suggests that reduced PPG is strongly associated with reductions in retinopathy and nephropathy. Finally, decreasing PPG in patients with IGT reduces the progression of diabetes. In conclusion, physicians should increase efforts to control PPG in order to further improve HbA(1c), and should also ensure close control of postprandial hyperglycaemic peaks so as to optimise patients' chances of avoiding cardiovascular complications. As for the prevention of CVD, further prospective intervention trials, powered to answer this question, are still required.

Glycaemic control is essential for effective cardiovascular risk reduction across the type 2 diabetes continuum

The growing prevalence of diabetes, an established risk factor for cardiovascular disease, threatens to significantly increase the global burden of cardiovascular morbidity and mortality. The risk of cardiovascular mortality is substantially higher in individuals with early glucose intolerance than in those with normal glucose levels and the pathological changes in vascular function begin many years before the diagnosis of overt type 2 diabetes. Postprandial hyperglycaemia is particularly deleterious to vascular function, and impaired glucose tolerance (IGT) - but not impaired fasting glucose - and may be an independent risk factor for cardiovascular disease throughout the glucose intolerance continuum. Evidence that molecular mechanisms induced by postprandial hyperglycaemia contribute to vascular damage has further highlighted the importance of targeting this component of the metabolic syndrome. Indeed, clinical trials have failed to convincingly show that interventions targeting fasting hyperglycaemia significantly reduce diabetes-associated cardiovascular risk. It may be necessary to refocus therapy to target postprandial hyperglycaemia to effectively reduce cardiovascular risk in the diabetic population. There is now direct evidence that pharmacological intervention, in the form of acarbose, to reduce postprandial hyperglycaemia, can significantly decrease the risk of cardiovascular events in individuals with IGT or type 2 diabetes.

Acarbose lowers serum triglyceride and postprandial chylomicron levels in type 2 diabetes

AIM

This study was designed to examine the therapeutic effect of acarbose on serum triglyceride (TG), free fatty acid (FFA), very low-density lipoprotein (VLDL) and chylomicron (CM) in the meal tolerance test (MTT) before and after acarbose treatment in type 2 diabetes mellitus (DM2).

METHODS

Effects of acarbose on postprandial lipid metabolism were examined in DM2 patients. The subjects with normotriglyceridaemia (TG > or = 1.7 mmol/l, n = 60) were divided to three groups (A, B and C), and DM2 patients with hypertriglyceridaemia (TG > 1.7 mmol/l, n = 20) were designated group D. Group A was a control, and group B was designed to examine the one-dose effect of acarbose (100 mg) on lipid levels in MTT using the balanced food of 400 kcal. In groups C and D, acarbose 300 mg/day was administered for 8 weeks, and MTT with the one-dose acarbose administration was performed. We determined the levels of fasting and postprandial levels of glucose, insulin, FFA and TG-rich lipoproteins such as CM and VLDL.

RESULTS

Acarbose treatment lowered plasma glucose levels and insulin secretion. In comparison among study groups A, B and C, acarbose significantly lowered serum TG levels in postprandial state. In group D, after the 8-week acarbose administration, fasting or postprandial FFA, TG and VLDL levels were also lowered. Interestingly, postprandial increase in CM was suppressed by acarbose administration in group B, C or D.

CONCLUSIONS

Acarbose lowers postprandial TG and CM levels in DM2 with either normotriglyceridaemia or hypertriglyceridaemia. Improvement of insulin resistance with acarbose may also reduce fasting TG levels in DM2 with hypertriglyceridaemia. Acarbose is a beneficial therapeutic agent to reduce TG levels in DM2 patients, thereby leading to suppression of cardiovascular events.

Is there a role for alpha-glucosidase inhibitors in the prevention of type 2 diabetes mellitus?

Type 2 diabetes mellitus is a major health problem associated with excess morbidity and mortality. As the prevalence of this metabolic disorder is rapidly increasing and current treatment fails to stabilise the disease in most patients, prevention should be considered as a key objective in the near future. People who develop type 2 diabetes pass through a phase of impaired glucose tolerance (IGT). Defects in the action and/or secretion of insulin are the two major abnormalities leading to development of glucose intolerance. Any intervention in the impaired glucose tolerance phase that reduces resistance to insulin or protects the beta-cells, or both, should prevent or delay progression to diabetes.Acarbose, miglitol and voglibose act by competitively inhibiting the alpha-glucosidases, a group of key intestinal enzymes involved in the digestion of carbohydrates. They decrease both postprandial hyperglycaemia and hyperinsulinaemia, and thereby may improve sensitivity to insulin and release the stress on beta-cells. These compounds do not induce hypoglycaemia and have a good safety profile, although gastrointestinal adverse effects may limit long-term compliance to therapy. The recent placebo-controlled prospective STOP-noninsulin-dependent diabetes mellitus (STOP-NIDDM) trial demonstrated that acarbose 100mg three times daily reduces the risk of developing type 2 diabetes in patients with IGT (relative risk reduction of 25% after a mean follow-up of 3.3 years). The 6-year Early Diabetes Intervention Trial (EDIT), comparing the effect of acarbose 50mg three times daily to that of metformin, showed a trend to a positive effect of acarbose compared with placebo, in a mid-term 3-year analysis, which should be confirmed in the final analysis. To our knowledge, no such prevention intervention trials have been or are currently being performed with miglitol or voglibose. In conclusion, because of its absence of toxicity and its particular mechanism of action on gastrointestinal tract and indirect consequences on both insulin action and beta-cell function, acarbose may be used to prevent type 2 diabetes. If the ongoing EDIT trial confirms the positive results of the recent STOP-NIDDM trial, acarbose could be used, either as an alternative or in addition to changes in lifestyle, to delay development of diabetes in patients with IGT. However, the best dosage of acarbose for this specific indication remains to be specified, especially when all three important parameters, efficacy, tolerance and cost, are taken into consideration.

Efficacy of acarbose in Chinese subjects with impaired glucose tolerance

This multicentre, double-blind, placebo-controlled study investigated the efficacy of acarbose in Chinese individuals with impaired glucose tolerance (determined using a 75 g oral glucose tolerance test). Subjects were randomised to either placebo or acarbose 50 mg t.i.d. for a period of 16 weeks. Primary efficacy variables were the maximum postprandial plasma glucose value (C(max)) and the serum insulin profile. Secondary efficacy parameters included postprandial glucose profile, maximum postprandial insulin concentration (C(max)), changes in lipid profile and blood pressure and HbA(1c) and body weight and conversion to Type 2 diabetes. In the intention-to-treat analysis, acarbose treatment resulted in significantly higher reductions in postprandial glucose and serum insulin concentrations compared to placebo. Triglyceride concentration was the only lipid parameter to be significantly reduced in acarbose subjects. Loss of body weight was also significantly greater for acarbose than placebo subjects. Some 19 individuals converted to Type 2 diabetes (seven acarbose, 12 placebo), but this difference was not significant. Acarbose is efficacious in improving the metabolic state of individuals with impaired glucose tolerance indicating a potential benefit for the delay or prevention of onset of Type 2 diabetes in Chinese subjects.

Acarbose improves glycemic control in insulin-treated Asian type 2 diabetic patients: results from a multinational, placebo-controlled study

The purpose of the study was to determine the efficacy and tolerability of acarbose in Asian type 2 diabetic patients insufficiently controlled by insulin. Asian type 2 diabetic patients on stable insulin dosages were enrolled into a multinational, double-blind, placebo-controlled parallel arm study. After a 2-week screening phase, patients were randomly assigned to 50 mg acarbose t.i.d. or matching placebo for 6 weeks, followed by 100 mg acarbose t.i.d. or placebo for 12 weeks. The primary efficacy parameter was change from baseline in HbA(1c); secondary variables included the changes in fasting and postprandial blood glucose. After 18 weeks of treatment there was a difference in HbA(1c) levels between the two treatment groups (-0.69%, 95% CI (-1.18; -0.2), P=0.008) in favour of acarbose. Reductions in 1-h postprandial glucose levels from baseline to endpoint were observed with acarbose treatment (P=0.029). There were no differences in fasting blood glucose, total triglyceride and cholesterol between the two groups. Safety profiles were similar for both treatment arms except for the higher incidence of flatulence in the acarbose group (28.6% vs. 16.4% for placebo). Adjunctive acarbose therapy offers an efficacious and safe means for improvement of glycemic control in Asian type 2 diabetic patients insufficiently controlled by insulin.

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.

Different effects of acarbose and glibenclamide on proinsulin and insulin profiles in people with Type 2 diabetes

AIM

In a double-blind, placebo-controlled study, we compared the effect of acarbose (A) and glibenclamide (G) on post-prandial (pp) and 24-h profiles of proinsulin and insulin.

METHODS

Twenty-seven patients with Type 2 diabetes mellitus insufficiently controlled with diet alone were randomised to receive acarbose, 100 mg thrice daily, glibenclamide, 1 mg thrice daily, or placebo. Before and after 16 weeks of treatment, 24-h profiles of proinsulin, insulin and glucose (fasting, 1 h after breakfast and every 3-h for a 24-h period) were measured under metabolic ward conditions with standardised meals.

RESULTS

With acarbose, a reduced 24-h level of proinsulin was observed compared with glibenclamide (AUC 1096 +/- 118 vs. 1604 +/- 174 pmol/l per h, P<0.05) at 16 weeks. The breakfast increment of proinsulin was lower with acarbose than glibenclamide (6.8 vs. 19.3 pmol/l, P<0.05) as was the level at that time (37.3 +/- 5.3 vs. 56.4 +/- 7.5 pmol/l, P<0.05). A lower AUC of insulin after treatment was also observed with acarbose than glibenclamide (7.9 +/- 0.9 vs. 14.8 +/- 4.5 nmol/l per h, P<0.05), as also for 1-h increment (81 +/- 26, vs. 380 +/- 120 pmol/l, P<0.01) and 1-h level (325 +/- 30 vs. 621 +/- 132 pmol/l, P<0.01). Acarbose reduced 1-h breakfast glucose increment (baseline 6.3 +/- 0.6, 16-week 3.5 +/- 0.6 mmol/l, P<0.01) and 1-h glucose level (18.1 +/- 1.1 and 14.5 +/- 1.3 mmol/l, P<0.01), whereas glibenclamide did not (6.6 +/- 0.7 vs. 5.4 +/- 0.6 mmol/l and 18.9 +/- 1.5 vs. 15.3 +/- 1.3 mmol/l).

CONCLUSIONS

Measurement of circadian excursions of proinsulin and insulin reveals distinct differences in meal-time proinsulin and insulin increment and level between acarbose and glibenclamide whereas fasting levels of these insulin fractions remained unaffected.