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

Therapeutic potential of acarbose in ameliorating the metabolic and endocrinological complications of polycystic ovarian syndrome: a review

Polycystic ovarian syndrome is a perplexed condition addressing endocrinal, cardiometabolic and gynaecological issues. It affects women of adolescent age and is drastically increasing in the Indo-Asian ethnicity over the recent years. According to Rotterdam criteria, PCOS is characterized by clinical or biochemical excess androgen and polycystic ovarian morphology; however, it has been established in the recent years that PCOS exacerbates to further serious metabolic conditions on the long term. This is a narrative literature review and not systematic review and is based on PubMed searches with relevant keywords "Polycystic ovarian syndrome AND acarbose OR metformin OR myoinositol; PCOS AND metabolic syndrome OR cardiovascular disease OR menstrual irregularity OR infertility OR chronic anovulation OR clinical hyperandrogenism" used in the title and are limited to articles published in English language with no time limits. A prominent aspect of PCOS is hyperandrogenaemia and hyperinsulinemia. About 50-70% of afflicted women have compensatory hyperinsulinemia and close to one tierce suffer from anovulation and infertility. Insulin resistance leads to metabolic complications and works with luteinizing hormone in increasing the ovarian androgen production. This excess androgen leads to clinical manifestations, irregular menstrual cycles and infertility. There isn't an entire cure, only the symptomatic clinical factors are considered rather than focusing on the underlying long-term complications. Therefore, the article focuses on a potent alpha glucosidase inhibitor, acarbose which suppresses the post meal glucose and insulin by delaying the absorption of complex carbs. It exhibits cardio-metabolic and hormonal benefits and is well tolerable in the south asian population. This review highlights the safety, effectiveness of acarbose in ameliorating the long-term complications of PCOS.

A systematic review, meta-analysis, dose-response, and meta-regression of the effects of acarbose intake on glycemic markers in adults

Purpose

Prior research has yielded mixed results regarding the impact of acarbose intake on glycemic markers. To provide a more comprehensive analysis, a systematic review and meta-analysis was performed to compile data from various randomized controlled trials (RCTs) examining the effects of acarbose intake on fasting blood sugar (FBS), insulin, hemoglobin A1C (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR) in adults.

Methods

To identify relevant literature up to April 2023, a comprehensive search was conducted on various scholarly databases, including PubMed, Web of Science, and Scopus databases. The effect size of the studies was evaluated using a random-effects model to calculate the weighted mean differences (WMD) and 95% confidence intervals (CI). Heterogeneity between studies was assessed using Cochran's Q test and I2.

Results

This systematic review and meta-analysis included a total of 101 RCTs with a total of 107 effect sizes. The effect sizes for FBS in milligrams per deciliter (mg/dl), insulin in picomoles per liter (pmol/l), hemoglobin A1C (HbA1c) in percentage (%), and homeostasis model assessment of insulin resistance (HOMA-IR) were 92, 46, 80, and 22, respectively. The pooled analysis indicated that acarbose intake resulted in significant decreases in FBS (p = 0.018), insulin (p < 0.001), HbA1c (p < 0.001), and HOMA-IR (p < 0.001).

Conclusion

The findings of this systematic review and meta-analysis suggest that acarbose intake can potentially lead to significant improvements in glycemic parameters by decreasing the levels of FBS, HbA1c, and insulin. However, larger and more rigorously designed studies are still needed to further evaluate and strengthen this association.

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.

Choice of Glucose-Lowering Drugs as Initial Monotherapy for Type 2 Diabetes Patients with Contraindications or Intolerance to Metformin: A Systematic Review and Meta-Analysis

BACKGROUND

There are multiple glucose-lowering drugs available as alternative initial monotherapy for type 2 diabetes patients with contraindications or intolerance to metformin. However, little comparative and systematic data are available for them as initial monotherapy. This study estimated and compared the treatment effects of glucose-lowering drugs as initial monotherapy for type 2 diabetes.

METHODS

PubMed, Web of Science, Embase, CNKI, Chongqing VIP, and WanFang Data from 1 January 1990 until 31 December 2020 were searched for randomized controlled trials which compared a glucose-lowering drug with placebo/lifestyle-intervention for type 2 diabetes. Drug classes included metformin, sulfonylureas (SUs), thiazolidinediones (TZDs), glinides (NIDEs), α-glucosidase inhibitors (AGIs), dipeptidyl peptidase-4 inhibitors (DPP-4is), sodium-glucose cotransporter-2 inhibitors (SGLT2is), insulins (INSs), and glucagon-like peptide-1 receptor agonists (GLP-1RAs).

RESULTS

A total of 185 trials were included, identifying 38,376 patients from 56 countries across six continents. When choosing an initial drug monotherapy alternative to metformin, SUs were most efficacious in reducing HbA1c (-1.39%; 95% CI -1.63, -1.16) and FPG (-2.70 mmol/L; 95% CI -3.18, -2.23), but increased hypoglycemia risks (5.44; 95% CI 2.11, 14.02). GLP-1RAs were most efficacious in reducing BMI (-1.05 kg/m²; 95% CI -1.81, -0.29) and TC (-0.42 mmol/L; 95% CI -0.61, -0.22). TZDs were most efficacious in increasing HDL-C (0.12 mmol/L; 95% CI 0.07, 0.17). SGLT2is were most efficacious in lowering SBP (-4.18 mmHg; 95% CI -4.84, -3.53). While AGIs conferred higher risk of AE-induced discontinuations (2.57; 95% CI 1.64, 4.03). Overall, only GLP-1RAs showed an integrated beneficial effect on all outcomes. Our results also confirmed the intraclass differences in treatment effects across drugs. Most trials were short-term, and no significant differences in mortality, total vascular events, myocardial infarction, heart failure, stroke, or diabetic nephropathy were observed across drug classes.

CONCLUSIONS

Our results suggest a potential treatment hierarchy for decision-makers, with GLP-1RAs being the preferred alternative therapy to metformin regarding their favorable efficacy and safety profiles.

Age, sex, disease severity, and disease duration difference in placebo response: implications from a meta-analysis of diabetes mellitus

BACKGROUND

The placebo response in patients with diabetes mellitus is very common. A systematic evaluation needs to be updated with the current evidence about the placebo response in diabetes mellitus and the associated factors in clinical trials of anti-diabetic medicine.

METHODS

Literature research was conducted in Medline, Embase, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for studies published between the date of inception and June 2019. Randomized placebo-controlled trials conducted in type 1and type 2 diabetes mellitus (T1DM/T2DM) were included. Random-effects model and meta-regression analysis were accordingly used. This meta-analysis was registered in PROSPERO as CRD42014009373.

RESULTS

Significantly weight elevation (effect size (ES) = 0.33 kg, 95% CI, 0.03 to 0.61 kg) was observed in patients with placebo treatments in T1DM subgroup while significantly HbA1c reduction (ES = - 0.12%, 95% CI, - 0.16 to - 0.07%) and weight reduction (ES = - 0.40 kg, 95% CI, - 0.50 to - 0.29 kg) were observed in patients with placebo treatments in T2DM subgroup. Greater HbA1c reduction was observed in patients with injectable placebo treatments (ES = - 0.22%, 95% CI, - 0.32 to - 0.11%) versus oral types (ES = - 0.09%, 95% CI, - 0.14 to - 0.04%) in T2DM (P = 0.03). Older age (β = - 0.01, 95% CI, - 0.02 to - 0.01, P < 0.01) and longer diabetes duration (β = - 0.02, 95% CI, - 0.03 to - 0.21 × 10^-2, P = 0.03) was significantly associated with more HbA1c reduction by placebo in T1DM. However, younger age (β = 0.02, 95% CI, 0.01 to 0.03, P = 0.01), lower male percentage (β = 0.01, 95% CI, 0.22 × 10^-2, 0.01, P < 0.01), higher baseline BMI (β = - 0.02, 95% CI, - 0.04 to - 0.26 × 10^-2, P = 0.02), and higher baseline HbA1c (β = - 0.09, 95% CI, - 0.16 to - 0.01, P = 0.02) were significantly associated with more HbA1c reduction by placebo in T2DM. Shorter diabetes duration (β = 0.06, 95% CI, 0.06 to 0.10, P < 0.01) was significantly associated with more weight reduction by placebo in T2DM. However, the associations between baseline BMI, baseline HbA1c, and placebo response were insignificant after the adjusted analyses.

CONCLUSION

The placebo response in diabetes mellitus was systematically outlined. Age, sex, disease severity (indirectly reflected by baseline BMI and baseline HbA1c), and disease duration were associated with placebo response in diabetes mellitus. The association between baseline BMI, baseline HbA1c, and placebo response may be the result of regression to the mean.

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.

Different clinical prognostic factors are associated with improved glycaemic control: findings from MARCH randomized trial

AIMS

Metformin and acarbose have comparable efficacy as initial therapy for HbA_1c reduction in Chinese patients with newly diagnosed Type 2 diabetes. However, not all participants achieved glycaemic control. Our aim was to discover a monotherapy predictor for therapeutic response in Type 2 diabetes on the basis of baseline features.

METHODS

Data from the MARCH trial were collected, resulting in 698 individuals being available for longitudinal analyses. All participants were divided into subgroups based on successful and unsuccessful achievement of the glycaemic target according to primary endpoints at week 24 (HbA_1c < 53 mmol/mol; 7.0%). Logistic regression analysis with stepwise variable selection was performed to assess the independent risk factors for good glycaemic control of monotherapy with metformin or acarbose.

RESULTS

Median HbA_1c was 66 ± 1 mmol/mol (8.2 ± 0.07%) in the metformin group at baseline, and 66 ± 1 mmol/mol (8.2 ± 0.07%) in the acarbose group. After 24 weeks of monotherapy, 79.8% of participants in the metformin group achieved glycaemic targets compared with 78.7% of those in the acarbose group. Multivariate regression analysis showed that BMI and fasting blood glucose were significant independent predictors for the maintenance of good glycaemic control in the metformin group, whereas phase I insulin secretion (Insulin/Glucose at 30 min, I30/G30) and duration of diabetes were associated with good glycaemic control in the acarbose group.

CONCLUSIONS

For newly diagnosed Type 2 diabetes, some clinical features and laboratory parameters are important prognostic factors for predicting drug responsiveness. Participants with a higher BMI and lower fasting blood glucose achieved good glycaemic control when metformin was selected as the initial treatment. Acarbose was best for participants with higher phase I insulin secretion (I30/G30) and shorter duration of Type 2 diabetes.

Rationale for treatment options for mealtime glucose control in patients with type 2 diabetes

While glycemic control is routinely assessed using HbA1c and fasting glucose measures, postprandial glucose (PPG) is also an important contributor of overall glycemia. Furthermore, PPG excursions have been linked to complications of diabetes. This review examines the effects of glucose-lowering therapies (including treatments administered at mealtime) on postprandial hyperglycemia in patients with type 2 diabetes. A PubMed search was conducted to identify clinical studies of treatments for mealtime glucose control in type 2 diabetes. Different treatments may have comparable effects on HbA1c but varying effects on PPG control and glucose fluctuations. Older classes of oral glucose-lowering treatments administered at mealtime to lower PPG include meglitinides and α-glucosidase inhibitors. Injectable therapies, including prandial insulin analogs, glucagon-like peptide-1 receptor agonists (GLP-1RAs), and the amylin analog pramlintide, all effectively target postprandial hyperglycemia. Compared with longer-acting GLP-1RAs, short-acting GLP-1RAs, such as exenatide twice daily and lixisenatide once daily, have a greater effect on PPG control, which is primarily mediated by a more pronounced effect on delayed gastric emptying. Dipeptidyl peptidase-4 inhibitors and sodium-glucose cotransporter 2 inhibitors also reduce postprandial hyperglycemia. To achieve more physiologically normal glycemic control, choice of therapy should ideally aim to address daily glucose fluctuations, including hyperglycemic peaks and hypoglycemic troughs, and long-term glycemic control.

Effect of nateglinide and glimepiride in reducing postprandial hyperglycaemia in patients with type 2 diabetes mellitus

Aim — The purpose of this study was to compare the effect of nateglinide on two-hour post-meal glucose levels with that of glimepiride in patients with type 2 diabetes mellitus. Methods — Glucose and insulin levels were measured during 14-hour profiles (comprising three meal challenges) and intravenous glucose tolerance tests performed before and after five-weeks of treatment with nateglinide (120 mg, a.c.) or glimepiride (1 mg, o.d.) in a randomised, two-centre, double-blind, crossover study in 26 patients with type 2 diabetes and fasting initial glucose levels < 13.9 mmol/L. Results — Mean two-hour postprandial glucose levels were significantly lower during nateglinide treatment than during glimepiride treatment (9.46 vs. 10.00 mmol/L, respectively; p<0.05). The 14-hour incremental glucose area under the curve was -2.2 mmol•h/L during nateglinide treatment and +6.2 mmol•h/L during glimepiride treatment (p<0.01). Nateglinide improved both the early insulin response during meals and the acute insulin response during intravenous glucose tolerance tests, restoring the biphasic insulin secretion pattern. Both insulin secretagogues improved intravenous glucose tolerance relative to the pre-treatment period, but only nateglinide restored a biphasic insulin profile. Conclusions — By restoring a more physiological post-load insulin response, nateglinide is more effective than glimepiride in controlling postprandial glucose excursions.

Comparison of glucose lowering effect of metformin and acarbose in type 2 diabetes mellitus: a meta-analysis

BACKGROUND

Metformin is the first-line oral hypoglycemic agent for type 2 diabetes mellitus recommended by international guidelines. However, little information exists comparing it with acarbose which is also commonly used in China. This study expanded knowledge by combining direct and indirect evidence to ascertain the glucose lowering effects of both drugs.

METHODS

PubMed (1980- December 2013) and China National Knowledge Infrastructure databases (1994-January 2014) were systematically searched for eligible randomized controlled trials from Chinese and English literatures. Meta-analysis was conducted to estimate the glucose lowering effects of metformin vs. acarbose, or either of them vs. common comparators (placebo or sulphonylureas), using random- and fixed-effect models. Bucher method with indirect treatment comparison calculator was applied to convert the summary estimates from the meta-analyses into weighted-mean-difference (WMD) and 95% confidence intervals (CIs) to represent the comparative efficacy between metformin and acarbose.

RESULTS

A total of 75 studies were included in the analysis. In direct comparison (8 trials), metformin reduced glycosylated hemoglobin (HbA1c) by 0.06% more than acarbose, with no significant difference (WMD,-0.06%; 95% CI, -0.32% to 0.20%). In indirect comparisons (67 trials), by using placebo and sulphonylureas as common comparators, metformin achieved significant HbA1c reduction than acarbose, by -0.38% (WMD,-0.38%, 95% CI, -0.736% to -0.024%) and -0.34% (WMD, -0.34%, 95% CI, -0.651% to -0.029%) respectively.

CONCLUSION

The glucose lowering effects of metformin monotherapy and acarbose monotherapy are the same by direct comparison, while metformin is a little better by indirect comparison. This implies that the effect of metformin is at least as good as acarbose's.

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.'

GLP-1 analog liraglutide enhances proinsulin processing in pancreatic β-cells via a PKA-dependent pathway

Hyperproinsulinemia has gained increasing attention in the development of type 2 diabetes. Clinical studies have demonstrated that glucagon-like peptide-1 (GLP-1)-based therapies significantly decrease plasma proinsulin/insulin ratio in patients with type 2 diabetes. However, the underlying mechanism remains unclear. Prohormone convertase (PC)-1/3 and PC2 are primarily responsible for processing proinsulin to insulin in pancreatic β-cells. We have recently reported that Pax6 mutation down-regulated PC1/3 and PC2 expression, resulting in defective proinsulin processing in Pax6 heterozygous mutant (Pax6(m/+)) mice. In this study, we investigated whether and how liraglutide, a novel GLP-1 analog, modulated proinsulin processing. Our results showed that liraglutide significantly up-regulated PC1/3 expression and decreased the proinsulin to insulin ratio in both Pax6(m/+) and db/db diabetic mice. In the cultured mouse pancreatic β-cell line, Min6, liraglutide stimulated PC1/3 and PC2 expression and lowered the proinsulin to insulin ratio in a dose- and time-dependent manner. Moreover, the beneficial effects of liraglutide on PC1/3 and PC2 expression and proinsulin processing were dependent on the GLP-1 receptor-mediated cAMP/protein kinase A signaling pathway. The same mechanism was recapitulated in isolated mouse islets. In conclusion, liraglutide enhanced PC1/3- and PC2-dependent proinsulin processing in pancreatic β-cells through the activation of the GLP-1 receptor/cAMP/protein kinase A signaling pathway. Our study provides a new mechanism for improvement of pancreatic β-cell function by the GLP-1-based therapy.

Comparisons of the efficacy of alpha glucosidase inhibitors on type 2 diabetes patients between Asian and Caucasian

Background

To compare the efficacy of glycemic control and insulin secretion of alpha glucosidase inhibitors (AGI) on type 2 diabetes patients between Asian and Caucasian.

Methodology/Principal Findings

The MEDLINE®, EMBASE®, CENTRAL were searched and qualified studies in Asian and Caucasian population comparing AGI treatment with placebo or other oral anti-diabetic drugs in type 2 diabetic patients were included. Totally 58 qualified studies were included. When AGI treatment was compared with placebo, a significant difference in HbA1c decline from baseline favoring AGI treatment was found in Asian (weighted mean difference (WMD), −0.50%; 95% CI, −0.66% to −0.34%) and in Caucasian a significant difference in HbA1c decline favoring AGI treatment was also found (WMD, −0.68%; 95% CI, −0.76% to −0.60%). In Asian, fasting plasma glucose was reduced with AGI treatment compared with placebo (WMD, −0.53 mmol/L; 95% CI, −0.91 to −0.14 mmol/L) and in Caucasian there was also a significant difference in FPG changes favoring AGI therapy (WMD, −0.88 mmol/L; 95% CI, −1.00 to −0.77 mmol/L). Studies in Asian showed a significant difference in fasting insulin changes favoring AGI treatment (WMD, −0.78 uU/ml; 95% CI, −0.96 to −0.59 uU/ml). While in Caucasian fasting insulin was decreased without significance with AGI treatment (WMD-1.24 uU/ml; 95% CI, −2.51 to 0.04 uU/ml). Body weight was decreased with AGI treatment in Asian (WMD, −1.00 kg; 95% CI, −1.69 to −0.31 kg) and was also decreased with AGI treatment in Caucasian (WMD, −0.73 kg; 95% CI, −1.13 to −0.33 kg).

Conclusions/Significance

According to results from this meta-analysis, the efficacy in glucose lowering, body weight reduction and insulin secretion decreasing of AGI treatment in Asian were comparable with those in Caucasian.

Glucose supply and insulin demand dynamics of antidiabetic agents

BACKGROUND

For microvascular outcomes, there is compelling historical and contemporary evidence for intensive blood glucose reduction in patients with either type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM). There is also strong evidence to support macrovascular benefit with intensive blood glucose reduction in T1DM. Similar evidence remains elusive for T2DM. Because cardiovascular outcome trials utilizing conventional algorithms to attain intensive blood glucose reduction have not demonstrated superiority to less aggressive blood glucose reduction (Action to Control Cardiovascular Risk in Diabetes; Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation; and Veterans Affairs Diabetes Trial), it should be considered that the means by which the blood glucose is reduced may be as important as the actual blood glucose.

METHODS

By identifying quantitative differences between antidiabetic agents on carbohydrate exposure (CE), hepatic glucose uptake (HGU), hepatic gluconeogenesis (GNG), insulin resistance (IR), peripheral glucose uptake (PGU), and peripheral insulin exposure (PIE), we created a pharmacokinetic/pharmacodynamic model to characterize the effect of the agents on the glucose supply and insulin demand dynamic. Glucose supply was defined as the cumulative percentage decrease in CE, increase in HGU, decrease in GNG, and decrease in IR, while insulin demand was defined as the cumulative percentage increase in PIE and PGU. With the glucose supply and insulin demand effects of each antidiabetic agent summated, the glucose supply (numerator) was divided by the insulin demand (denominator) to create a value representative of the glucose supply and insulin demand dynamic (SD ratio).

RESULTS

Alpha-glucosidase inhibitors (1.25), metformin (2.20), and thiazolidinediones (TZDs; 1.25-1.32) demonstrate a greater effect on glucose supply (SD ratio >1), while secretagogues (0.69-0.81), basal insulins (0.77-0.79), and bolus insulins (0.62-0.67) demonstrate a greater effect on insulin demand (SD ratio <1).

CONCLUSION

Alpha-glucosidase inhibitors, metformin, and TZDs demonstrate a greater effect on glucose supply, while secretagogues, basal insulin, and bolus insulin demonstrate a greater effect on insulin demand. Because T2DM cardiovascular outcome trials have not demonstrated macrovascular benefit with more aggressive blood glucose reduction when using conventional algorithms that predominantly focus on insulin demand, it would appear logical to consider a model that incorporates both the extent of blood glucose lowering (hemoglobin A1c) and the means by which the blood glucose was reduced (SD ratio) when considering macrovascular outcomes.

Acarbose: oral anti-diabetes drug with additional cardiovascular benefits

Acarbose is an alpha-glucosidase inhibitor acting specifically at the level of postprandial glucose excursion. This compound lowers HbA(1c) by 0.5-1% in patients with Type 2 diabetes, either drug naive or in combination with other antidiabetic drugs. In those with impaired glucose tolerance (IGT), it reduces the incidence of newly diagnosed diabetes by 36.4%. Furthermore, it has beneficial effects on overweight, reduces blood pressure and triglycerides, and downregulates biomarkers of low-grade inflammation. In the Study To Prevent Non-Insulin-Dependent-Diabetes-Mellitus (STOP-NIDDM) trial, acarbose significantly reduced the progression of intima media thickness, incidence of cardiovascular events and of newly diagnosed hypertension. In a meta-analysis of patients with Type 2 diabetes (MERIA), acarbose intake was associated with a reduction of cardiovascular events by 35%. Acarbose is a very safe drug but in approximately 30% of patients, it can cause gastrointestinal complaints due to its mode of action, which in the majority disappear after 1-2 months. Acarbose is approved for treatment of IGT in 25 countries. It can be given alone or in combination with other oral antidiabetics and insulin. Acarbose is particularly effective in those with IGT and early diabetes and patients with comorbidities of the metabolic syndrome.

Cardiovascular benefits and safety profile of acarbose therapy in prediabetes and established type 2 diabetes

Dysglycaemic disease is one of the most important health issues facing the world in the 21^st century. Patients with type 2 diabetes and individuals with prediabetes are at risk of developing macrovascular and microvascular complications. Long-term management strategies are therefore required that are effective at controlling dysglycaemia, well tolerated and, ideally, offer additional cardiovascular disease (CVD) risk-reduction benefits. The efficacy, safety and tolerability of the α-glucosidase inhibitor acarbose have been well-established in a wide range of patient populations in both clinical and community trials. In addition, acarbose has been shown to reduce cardiovascular complications in type 2 diabetes and prevent hypertension and CVD in individuals with impaired glucose tolerance (IGT). Acarbose has a very good safety profile and, owing to its straightforward, non-systemic mode of action, avoids most adverse events. The most common side-effects of acarbose are mild-to-moderate gastrointestinal complaints that subside as treatment continues. They can be minimised through the use of an appropriate stepwise dosing regimen and careful choice of diet. Acarbose is therefore a valuable option for the management of type 2 diabetes and, as the only oral antidiabetes agent approved for the treatment of prediabetes, can help to improve clinical management across the dysglycaemic disease continuum.

Postprandial hyperglycaemia and vascular damage--the benefits of acarbose

Traditional risk factors do not fully explain the increased risk of cardiovascular disease (CVD) in diabetes. Epidemiology shows that hyperglycaemia is a continuous CVD risk factor and that two-hour postprandial glucose levels are more strongly associated with CVD than fasting glucose. Good glycaemic control is proven to reduce the risk of microvascular complications, but equivalent evidence for CVD risk reduction is lacking. However, in the Study to Prevent Non-Insulin Dependent Diabetes Mellitus (STOP-NIDDM), acarbose reduced the risk of diabetes in those with impaired glucose tolerance by 36% (p=0.0017) and the risk of any cardiovascular event by 49% (p=0.0326) versus placebo. Furthermore, a meta-analysis of trials of acarbose in patients with type 2 diabetes suggests a significant reduction of CVD events. This review examines evidence that postprandial hyperglycaemia plays a major role in vascular damage, particularly through non-traditional risk factors such as oxidative stress and subclinical inflammation, and how acarbose may prevent this damage.

Combined treatment with exercise training and acarbose improves metabolic control and cardiovascular risk factor profile in subjects with mild type 2 diabetes

OBJECTIVE

The effect of exercise training and acarbose on glycemic control, insulin sensitivity, and phenotype was investigated in mild type 2 diabetes.

RESEARCH DESIGN AND METHODS

Sixty-two men and women with type 2 diabetes were randomized to 12 weeks of structured exercise training with or without acarbose treatment or to acarbose alone. Glycemic control was determined by HbA(1c) (A1C), insulin sensitivity (M value) by euglycemic-hyperinsulinemic clamp, and regional fat distribution by computerized tomography and dual X-ray absorptiometry. Physical fitness was determined as maximal oxygen uptake (Vo(2max)). All investigations were performed before and after the intervention.

RESULTS

Forty-eight subjects completed the study. Exercise improved M value by 92% (P = 0.017) and decreased total and truncal fat (P = 0.002, 0.001) and systolic blood pressure (P = 0.01) but had no significant effect on Vo(2max) or A1C level. The combination of exercise and acarbose significantly decreased fasting plasma glucose, A1C, lipids, and diastolic blood pressure and increased Vo(2max), whereas effects on M value and body composition were comparable with that of exercise alone. Acarbose alone had no significant effect on either M value or A1C but decreased systolic (P = 0.001) and diastolic blood pressure (P = 0.001) and fasting proinsulin level (P = 0.009). Multiple regression analysis showed that addition of acarbose to exercise improved glycemic control.

CONCLUSIONS

In subjects with mild type 2 diabetes, exercise training improved insulin sensitivity but had no effect on glycemic control. The addition of acarbose to exercise, however, was associated with significant improvement of glycemic control and possibly cardiovascular risk factors.

Alpha-glucosidase inhibitors for type 2 diabetes mellitus

BACKGROUND

Alpha-glucosidase inhibitors such as acarbose or miglitol, have the potential to improve glycemic control in type 2 diabetes mellitus. The true value of these agents, especially in relation to diabetes related mortality and morbidity, has never been investigated in a systematic literature review and meta-analysis.

OBJECTIVES

To assess the effects of alpha-glucosidase inhibitors s in patients with type 2 diabetes mellitus.

SEARCH STRATEGY

We searched The Cochrane Library, MEDLINE, EMBASE, Current Contents, LILACS, databases of ongoing trials, reference lists of reviews on the topic of alpha-glucosidase inhibitors and we contacted experts and manufacturers for additional trials. Date of most recent search: December 2003 (Current Contents) and April 2003 (other databases).

SELECTION CRITERIA

Randomised controlled trials of at least 12 weeks duration comparing alpha-glucosidase inhibitor monotherapy in patients with type 2 diabetes with any other intervention and that included at least one of the following outcomes: mortality, morbidity, quality of life, glycemic control, lipids, insulin levels, body weight, adverse events.

DATA COLLECTION AND ANALYSIS

Two reviewers read all abstracts, assessed quality and extracted data independently. Discrepancies were resolved by consensus or by the judgement of a third reviewer. A statistician checked all extracted data entrance in the database. We attempted to contact all authors for data clarification.

MAIN RESULTS

We included 41 trials (8130 participants), 30 investigated acarbose, seven miglitol, one trial voglibose and three trials compared different alpha-glucosidase inhibitors. Study duration was 24 weeks in most cases and only two studies lasted amply longer than one year. We found only few data on mortality, morbidity and quality of life. Acarbose had a clear effect on glycemic control compared to placebo: glycated haemoglobin -0.8% (95% confidence interval -0.9 to -0.7), fasting blood glucose -1.1 mmol/L (95% confidence interval -1.4 to -0.9), post-load blood glucose -2.3 mmol/L (95% confidence interval -2.7 to -1.9). The effect on glycated haemoglobin by acarbose was not dose-dependent. We found a decreasing effect on post-load insulin and no clinically relevant effects on lipids or body weight. Adverse effects were mostly of gastro-intestinal origin and dose dependent. Compared to sulphonylurea, acarbose decreased fasting and post-load insulin levels by -24.8 pmol/L (95% confidence interval -43.3 to -6.3) and -133.2 pmol/L (95% confidence interval -184.5 to -81.8) respectively and acarbose caused more adverse effects.

AUTHORS' CONCLUSIONS

It remains unclear whether alpha-glucosidase inhibitors influence mortality or morbidity in patients with type 2 diabetes. Conversely, they have a significant effect on glycemic control and insulin levels, but no statistically significant effect on lipids and body weight. These effects are less sure when alpha-glucosidase inhibitors are used for a longer duration. Acarbose dosages higher than 50 mg TID offer no additional effect on glycated hemoglobin but more adverse effects instead. Compared to sulphonylurea, alpha-glucosidase inhibitors lower fasting and post-load insulin levels and have an inferior profile regarding glycemic control and adverse effects.

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.

Influence of treatment with acarbose or glibenclamide on insulin sensitivity in type 2 diabetic patients

AIM

The aim of our double-blind, placebo-controlled study was to compare the effect of acarbose and glibenclamide on the insulin sensitivity in type 2 diabetes.

METHODS

We investigated 77 patients (mean age 58.7 years, mean BMI 27.3 kg/m2), treated by diet alone for at least 4 weeks. The subjects were randomized into three treatment groups for 16 weeks: 100 mg t.i.d. acarbose (n = 25) or 1 mg t.i.d. glibenclamide (n = 27) or one t.i.d. placebo (n = 25). Before and after therapy, the levels of fasting plasma glucose, glycosylated haemoglobin, fasting insulin, plasma glucose and insulin 1 h after a standardized breakfast were measured and insulin sensitivity determined by euglycaemic hyperinsulinaemic clamp test.

RESULTS

After the treatment period, BMI in the acarbose and placebo group decreased significantly, whereas in the glibenclamide group a significant increase was observed. Fasting plasma glucose was only significant reduced under glibenclamide. The postprandial glucose decreased significantly after acarbose (13.8 vs. 11.4 mmol/l, p < 0.05) and glibenclamide treatment (14.6 vs. 11.4 mmol/l, p < 0.05) and was unchanged under placebo (13.8 vs. 13.7 mmol/l). The fasting insulin levels remained unchanged in all three groups, whereas postprandial insulin values increased significantly under glibenclamide. Neither acarbose nor glibenclamide significantly changed insulin sensitivity [acarbose: glucose disposal rate before treatment 2.3 mg/kg body weight/min/insulin, after treatment 3.2; glibenclamide 2.2 vs. 2.1; placebo 2.6 vs. 3.0].

CONCLUSIONS

Our results show a more substantial improvement of glucose control under glibenclamide than under acarbose which, however, was not associated with an increase of insulin sensitivity.