Antidiabetic agents in subjects with mild dysglycaemia: prevention or early treatment of type 2 diabetes?

Effects of Insulin Therapy and Oral Hypoglycemic Agents on Glycemic Control for Type 2 Diabetes Mellitus Patients in China-A Case Control Study

OBJECTIVE

The purpose of the study was to compare glycemic control in patients with type 2 diabetes (T2DM) receiving insulin therapy (IT) or oral hypoglycemic agents (OHA), and explore associations between treatment modality and pancreatic beta-cell function.

METHODS

A matched, case-control study was conducted from April, 2016 to November, 2016. 2 272 patients with T2DM were identified from electronic medical records at four academic hospitals in China. Based on 1 136 eligible patients using IT, eligible 1 136 OHA patients were matched by age and duration at a ratio of 1:1. Logistic regression was used to examine the relationship between IT and glycemic control. Multiple linear regression addressed impact factors of HOMA-β.

RESULTS

There was no significant difference between IT and OHA groups in gender, age, diabetes duration, body mass index (BMI), fasting plasma glucose (FPG), systolic blood pressure (SBP), serum lipids and smoking history (p>0.05). We stratified subjects by diabetes duration, only when the duration was less than 5 years, HbA1c in OHA group was superior to IT (P=0.017). There were no significant differences between groups in HbA1c when disease duration was≥5 years. Even in subjects with short diabetes duration (<5 years), IT did not significantly impact glycemic control (p=0.071, OR=0.577). Multiple linear regression analysis showed that IT (p=0.001), diabetes duration (p=0.038), BMI (P<0.001), sulfonylurea use (P=0.001) were significant and independent predictors of HOMA-β.

CONCLUSIONS

In patients with short diabetes duration (<5 years), oral hypoglycemic therapy achieved better glycemic control than insulin therapy. Moreover, insulin use was not an impact factor of poor glycemic control. In addition, using insulin can protect beta-cell function.

Anti-Diabetic and Anti-Nephritic Activities of Grifola frondosa Mycelium Polysaccharides in Diet-Streptozotocin-Induced Diabetic Rats Via Modulation on Oxidative Stress

Grifola frondosa is an edible fungus with a variety of potential pharmacological activities. This study investigates the hypoglycemic, anti-diabetic nephritic, and antioxidant properties of G. frondosa polysaccharides in diet-streptozotocin-induced diabetic rats. After a 4-week treatment with 100 mg/kg of metformin and 200 mg/kg of one of four different G. frondosa polysaccharide mixtures (especially GFPS3 and GFPS4), diabetic rats had enhanced body weight and suppressed plasma glucose, indicating the hypoglycemic activities of the G. frondosa polysaccharides. G. frondosa polysaccharides regulated the level of serum creatinine, blood urea nitrogen, N-acetyl-β-D-glucosaminidase, and albuminuria; inhibited the serum levels of interleukin (IL)-2, IL-6, and TNF-α; and enhanced the serum levels of matrix metalloproteinase 9 and interferon-α, confirming their anti-diabetic nephritic activities. G. frondosa polysaccharides ameliorated the pathological alterations in the kidneys of diabetic rats. Moreover, G. frondosa polysaccharides modulated the serum levels of oxidant factors such as superoxide dismutase, glutathione peroxidase, catalase, malondialdehyde, and reactive oxygen species, revealing their antioxidant properties. Furthermore, the administration of G. frondosa polysaccharides inhibited nuclear factor kappa B activities in the serum and kidneys. All of the data revealed that the activation of nuclear factor kappa B plays a central role in G. frondosa polysaccharide-mediated anti-diabetic and anti-nephritic activities.

The Hypoglycemic, Hypolipidemic, and Anti-Diabetic Nephritic Activities of Zeaxanthin in Diet-Streptozotocin-Induced Diabetic Sprague Dawley Rats

Zeaxanthin (ZA), an important compound found in Lycium barbarum, shows various pharmacodynamic effects. In our present study, a high-fat, high-sucrose diet and streptozotocin (STZ)-induced diabetic rat model was used to investigate the antidiabetic activities of ZA. After a 4-week administration of 200 and 400 mg/kg of ZA and 100 mg/kg of metformin hydrochloride, various blood biochemical indexes were detected. ZA strongly normalized the reduced bodyweight and enhanced fasting blood glucose in diabetic rats. The positive data obtained from the oral glucose tolerance test further confirmed its antidiabetic effects. ZA displayed significant hypolipidemic activities indicated by its modulation of serum levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and total cholesterol. The antidiabetic nephropathy of ZA was confirmed by its regulation of pathological kidney structures, urine levels of n-acetyl-β-d-glucosaminidase and albuminuria, and serum levels of urea nitrogen. ZA inhibited the serum levels of inflammatory factors including interleukin-2 (IL-2), IL-6, tumor necrosis factor-α, and nuclear factor kappa B, further confirming its renal protection. Moreover, the serum imbalances in superoxide dismutase, glutathione peroxidase, methane dicarboxylic aldehyde, and catalase were normalized by ZA, suggesting its antioxidant properties. Altogether, ZA produced hypoglycemic, hypolipidemic, and antidiabetic nephritic effects in a diet-STZ-induced diabetic rat model.

Hpyerglycemic and anti-diabetic nephritis activities of polysaccharides separated from Auricularia auricular in diet-streptozotocin-induced diabetic rats

Due to substantial morbidity and complications including nephropathy, a search for alternative treatment of diabetes mellitus is urgently required. The present study aimed to investigate the hypoglycemic and anti-diabetic nephropathy activities of polysaccharides separated from Auricularia auricular (AAP). Diet streptozotocin (STZ)-induced diabetic Sprague-Dawley rats were orally treated with metformin (100 mg/kg; positive control) and AAP (100 and 400 mg/kg) for four weeks, and parameters in the serum and liver associated with blood glucose, free radicals and nephropathy were determined. Similar to metformin, AAP treatment strongly reduced blood glucose levels by promoting glucose metabolism. The anti-oxidative activity of AAP, which was indicated by the modulation of superoxide dismutase, glutathione peroxidase, reactive oxygen species and methane dicarboxylic aldehyde levels in serum, was observed in diabetic rats. Furthermore, the regulatory effects of AAP on blood urea nitrogen, creatinine, uric protein and inflammatory-related factors revealed its protection against diabetic nephropathy. The present data suggests that AAP-mediated anti-diabetic and anti-nephritic effects are partially associated with their modulations on the anti-oxidative system and nuclear factor kappa B-related signaling pathway. In conclusion, AAP has potential to be a novel source of treatments for diabetes.

Chrysoeriol and other polyphenols from Tecoma stans with lipase inhibitory activity

ETHNOPHARMACOLOGICAL RELEVANCE

Tecoma stans is traditionally used by several ethnical groups in Mexico and Central America to treat diabetes. This species is mentioned in the majority of the ethnopharmacological studies compiled in Mexico focused in medicinal plants used as anti-diabetic treatment.

AIM OF THE STUDY

Recently, this plant was found to display a high level of pancreatic lipase inhibitory activity, in addition to the several action mechanisms already described. Here we show the phytochemical and in vitro pharmacological characterization of some of the compounds responsible for the antilipase activity.

MATERIALS AND METHODS

Starting with a hydroalcoholic extract, fractions were obtained by liquid-liquid separation and successive processes of column chromatography purifications. Lipase inhibitory activity was measured employing a spectrophotometric analysis. For structural elucidation (1)H and (13)C NMR experiments were used. HPLC was used to quantify and confirm the identity of the bioactive compounds.

RESULTS

Bio-guided chemical purification of the hydroalcoholic extract produced an organic fraction (ethyl acetate, TsEA), flavone fractions (TsC1F13), (TsC1F15), (TsC1F16) and isolated compounds (chrysoeriol, apigenin, luteolin, and verbascoside) with the capability to inhibit the activity of pancreatic lipase. The most active fraction (TsC2F6B) was constituted by a mixture of Chrysoeriol (5,7-dihydroxy-2-[4-hydroxy-3-methoxyphenyl]chromen-4-one, 96% ) and Apigenin (4%). This flavone mixture displayed a percentage of inhibition of 85% when it was eavaluated at 0.25mg/mL. Luteolin and chrysoeriol produced a noncompetitive and mixed inhibition with values of IC50=63 and 158µM respectively. The content of chrysoeriol was also quantified in the hydroalcoholic extract (TsHAE) and organic fraction (TsEA) as 1% and 7% respectively. All of this confirms that high proportion of both flavones produce an increase of the biological activity due to they show the highest inhibition of lipase enzyme in a concentration dependant way.

CONCLUSIONS

These results evidence that the medicinal use of T. stans could be in part because of its lipase inhibitory activity allowing to adapt the administration of this plant before meals. Also this data could help to develop a novel phytopharmaceutical drug (standardized in luteolin, chrysoeriol, and apigenin) auxiliary for the Type 2 Diabetes mellitus.

Antidiabetic and Antinephritic Activities of Aqueous Extract of Cordyceps militaris Fruit Body in Diet-Streptozotocin-Induced Diabetic Sprague Dawley Rats

Cordyceps militaris has long been used as a crude drug and folk tonic food in East Asia. The present study aims to evaluate the antidiabetic and antinephritic effects of the aqueous extract of the Cordyceps militaris fruit body (CM) in diet-streptozotocin- (STZ-) induced diabetic rats. During four weeks of continuous oral administration of CM at doses of 0.5, 1.0, and 2.0 g/kg and metformin at 100 mg/kg, the fasting blood glucose and bodyweight of each rat were monitored. Hypoglycemic effects of CM on diabetic rats were indicated by decreases in plasma glucose, food and water intake, and urine output. The hypolipidemic activity of CM was confirmed by the normalization of total cholesterol, triglycerides, and low- and high-density lipoprotein cholesterol in diabetic rats. Inhibitory effects on albuminuria, creatinine, urea nitrogen, and n-acetyl-β-d-glucosaminidase verified CM's renal protective activity in diabetic rats. Furthermore, CM exerted beneficial modulation of inflammatory factors and oxidative enzymes. Compared with untreated diabetic rats, CM decreased the expression of phosphor-AKT and phosphor-GSK-3β in the kidneys. Altogether, via attenuating oxidative stress, CM displayed antidiabetic and antinephritic activities in diet-STZ-induced diabetic rats.

Lycium barbarum Polysaccharide Mediated the Antidiabetic and Antinephritic Effects in Diet-Streptozotocin-Induced Diabetic Sprague Dawley Rats via Regulation of NF-κB

Lycium barbarum, extensively utilized as a medicinal plant in China for years, exhibits antitumor, immunoregulative, hepatoprotective, and neuroprotective properties. The present study aims to investigate the hyperglycemic and antidiabetic nephritic effects of polysaccharide which is separated from Lycium barbarum (LBPS) in high-fat diet-streptozotocin- (STZ-) induced rat models. The reduced bodyweight and enhanced blood glucose concentration in serum were observed in diabetic rats, and they were significantly normalized to the healthy level by 100 mg/kg of metformin (Met) and LBPS at doses of 100, 250, and 500 mg/kg. LBPS inhibited albuminuria and blood urea nitrogen concentration and serum levels of inflammatory factors including IL-2, IL-6, TNF-α, IFN-α, MCP-1, and ICAM-1 compared with diabetic rats, and it indicates the protection on renal damage. Furthermore, the activities of SOD and GSH-Px in serum were enhanced strikingly by LBPS which suggests its antioxidation effects. LBPS, compared with nontreated diabetic rats, inhibited the expression of phosphor-nuclear factors kappa B (NF-κB) and inhibitor kappa B alpha in kidney tissues. Collectively, LBPS possesses antidiabetic and antinephritic effects related to NF-κB-mediated antioxidant and antiinflammatory activities.

Studies on the Antidiabetic and Antinephritic Activities of Paecilomyces hepiali Water Extract in Diet-Streptozotocin-Induced Diabetic Sprague Dawley Rats

Paecilomyces hepiali is a fungus widely used in Asian countries for various potential pharmacological activities. The present study aims to evaluate the antidiabetic and antinephritic effects of the Paecilomyces hepiali mycelium water extract (PHC) in diabetic rat, which is established by eight-week high-fat diet administration followed by one-week tail intravenous injection of 25 mg/kg streptozotocin (STZ). After four-week 0.12 g/kg metformin and PHC at doses of 0.08, 0.4, and 2.0 g/kg treatment, an increment of body weight, a decrement of plasma glucose, low levels of total cholesterol, and low density lipoprotein cholesterol in diabetic rats were observed. PHC promotes glucose metabolism by enhancing insulin, pyruvate kinase activity, and increasing the synthesis of glycogen. PHC normalized the disturbed levels of superoxide dismutase, methane dicarboxylic aldehyde, and glutathione peroxidase in kidney. The inhibitory effects on the levels of interleukin-2, interleukin-6, interleukin-10, and tumor necrosis factor-α in serum and kidney revealed the protection of PHC against diabetic nephropathy. Compared with nontreated diabetic rats, four-week PHC treatment resulted in a decrement on nuclear factor kappa B expression in kidney. These results show that Paecilomyces hepiali possesses antidiabetic and antinephritic effects which are related to the modulation of nuclear factor kappa B activity.

Antihyperglycemic effects of Pandanus amaryllifolius Roxb. leaf extract

Background:

Diabetes mellitus is one of the leading chronic diseases worldwide. In patients with poor glycemic control, high blood glucose level may lead to other life-threatening complications. Pandanus amaryllifolius Roxb. (PA) leaves are used in traditional medicine for the treatment of diabetes.

Objective:

This study evaluated the effect of crude extract from PA leaves on blood glucose level and the hypoglycemic mechanisms.

Materials and Methods:

Thirty healthy volunteers were asked to drink PA tea (test-group) or hot water (control group) 15 min after glucose loading (75 g) in a standard oral glucose tolerance test. To study hypoglycemic mechanisms, PA leaves were extracted using two different methods. Method 1; dried PA leaves were extracted with distilled water at 90°C for 15 min, and method 2; dried PA leaves were extracted with 95% ethanol. Both PA extracts were tested for α-glucosidase enzyme inhibition, insulin stimulation, and glucose uptake stimulation.

Results:

The average of blood glucose level in the control group was 5.55 ± 0.98 mmol/l, while in PA treated group was 6.16 ± 0.79 mmol/l which were statistically different (P < 0.001). The results of antihyperglycemic mechanism showed that PA extracts, prepared both methods, could inhibit α-glucosidase enzyme and induce insulin production in rat pancreatic cell (RINm5F) in dose-dependent manner (P < 0.05).

Conclusions:

The knowledge gained from this research can be used as a basis for a new drug discovery for the treatment of diabetes.

Prevention of type 2 diabetes in obese at-risk subjects: a systematic review and meta-analysis

Different intervention strategies can prevent new cases of type 2 diabetes (T2DM) in obese subjects. The present systematic review and meta-analysis evaluates the effectiveness of different strategies in prevention of type 2 diabetes in obese subjects. Studies were grouped into five different strategies: (1) physical activity ± diet; (2) anti-diabetic drugs (glitazones, metformin, glinides, alfa-glucosidase inhibitors); (3) antihypertensive drugs (ACE inhibitors, ARB); (4) weight loss-promoting drugs and lipid-lowering drugs (orlistat, bezafibrate, phentermine/topiramate controlled release); and (5) bariatric surgery. Only controlled studies, dealing with subjects BMI ≥ 30 kg/m(2), were included in the analysis, whether randomized or non-randomized studies. Appropriate methodology (PRISMA statement) was adhered to. Publication bias was formally assessed. Eighteen studies (43,669 subjects, 30,774 with impaired glucose tolerance and/or impaired fasting glucose), published in English language as full papers, were analyzed to identify predictors of new cases of T2DM and were included in a meta-analysis (random-effects model) to study the effect of different strategies. Intervention effect (new cases of diabetes) was expressed as odds ratio (OR), with 95 % confidence intervals (CIs). In obese subjects, non-surgical strategies were able to prevent T2DM, with different effectiveness [OR from 0.44 (0.36-0.52) to 0.86 (0.80-0.92)]; in morbidly obese subjects, bariatric surgery was highly effective [OR = 0.10 (0.02-0.49)]. At meta-regression analysis, factors associated with effectiveness were weight loss, young age and fasting insulin levels. Publication bias was present only when considering all studies together. These data indicate that several strategies, with different effectiveness, can prevent T2DM in obese subjects.

Prevention of type 2 diabetes; a systematic review and meta-analysis of different intervention strategies

AIM

Different intervention strategies can prevent type 2 diabetes (T2DM). Aim of the present systematic review and meta-analysis was to evaluate the effectiveness of different strategies.

METHODS

Studies were grouped into 15 different strategies: 1: diet plus physical activity; 2: physical activity; 3-6: anti-diabetic drugs [glitazones, metformin, beta-cell stimulating drugs (sulphanylureas, glinides), alfa-glucosidase inhibitors]; 7-8: cardiovascular drugs (ACE inhibitors, ARB, calcium antagonists); 9-14 [diets, lipid-affecting drugs (orlistat, bezafibrate), vitamins, micronutrients, estrogens, alcohol, coffee]; 15: bariatric surgery. Only controlled studies were included in the analysis, whether randomized, non-randomized, observational studies, whether primarily designed to assess incident cases of diabetes, or performed with other purposes, such as control of hypertension, of ischemic heart disease or prevention of cardiovascular events. Appropriate methodology [preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement] was used. Seventy-one studies (490 813 subjects), published as full papers, were analysed to identify predictors of new cases of T2DM, and were included in a meta-analysis (random-effects model) to study the effect of different strategies. Intervention effect (new cases of diabetes) was expressed as odds ratio (OR), with 95% confidence intervals (C.I.s). Publication bias was formally assessed.

RESULTS

Body mass index was in the overweight range for 13 groups, obese or morbidly obese in lipid-affecting drugs and in bariatric surgery. Non-surgical strategies, except for beta-cell stimulating drugs, estrogens and vitamins, were able to prevent T2DM, with different effectiveness, from 0.37 (C.I. 0.26-0.52) to 0.85 (C.I. 0.77-0.93); the most effective strategy was bariatric surgery in morbidly obese subjects [0.16 (C.I. 0.11,0.24)]. At meta-regression analysis, age of subjects and amount of weight lost were associated with effectiveness of intervention.

CONCLUSIONS

These data indicate that several strategies prevent T2DM, making it possible to make a choice for the individual subject.

Glucagon-like peptide-1 receptor agonists versus insulin glargine for type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Glucagon-like peptide-1 (GLP-1) receptor agonists are a new class of hypoglycemic drugs, including exenatide, liraglutide, albiglutide, lixisenatide, and taspoglutide. Insulin glargine is a standard agent used to supplement basal insulin in type 2 diabetes mellitus (T2DM).

OBJECTIVE

The aim of this study was to review the efficacy and safety profiles of GLP-1 receptor agonists versus insulin glargine in type 2 diabetic patients who have not achieved treatment goals with oral hypoglycemic agents.

METHODS

The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and the database of ongoing trials were searched from inception through April 2010. Additional data were sought from relevant Web sites, the American Diabetes Association, reference lists of included trials and related (systematic) reviews, and industry. Randomized controlled trials (RCTs) were selected if they were ≥3 months in duration, compared GLP-1 receptor agonists with insulin glargine in patients with T2DM, and included ≥1 of the following outcomes: mortality, complications of T2DM, glycemie control, weight, lipids, blood pressure, adverse effects, and health-related quality of life. Quasirandomized controlled trials were excluded. The quality of the eligible studies was assessed on the basis of the following aspects: randomization procedure, allocation concealment, blinding, incomplete outcome data (intent-to-treat [ITT] analysis), selective outcome reporting, and publication bias.

RESULTS

A total of 410 citations were retrieved; 5 multicenter RCTs that met the inclusion criteria were identified. They were all open-label designs with an insulin glargine arm, predefined outcomes reported, and ITT analysis. One trial had an unclear randomization procedure and allocation concealment. Publication bias was not able to be determined. No data wete found with regard to mortality or diabetes-associated complications, and few data were found on quality of life. The results of the metaanalysis suggest that insulin glargine was significantly better in reducing the fasting blood glucose (mean difference [MD] [95% CI], 1.31 [1.04 to 1.58]; P < 0.001), but exhibits greater incidence of nocturnal hypoglycemia (risk ratio [RR] [95% CI], 0.40 [0.23 to 0.71]; P = 0.002) and influenza (RR [95% CI], 0.56 [0.32 to 0.98]; P = 0.04). GLP-1 receptor agonists are more conducive to reducing weight (MD [95% CI], -3.96 [-5.14 to -2.77]; P < 0.001), postprandial blood glucose (after breakfast, P < 0.001; after dinner, P < 0.001), and LDL-C (MD [95% CI], -0.18 [-0.28 to -0.08]; P < 0.001), but have significantly more gastrointestinal adverse effects (eg, nausea/ vomiting, P < 0.001). There were no significant differences between GLP-1 receptor agonists and insulin glargine in reducing glycosylated hemoglobin (HbA1c) levels (MD [95% CI], -0.03 [-0.13 to 0.08]) and the overall incidence of hypoglycemia (RR [95% CI], 0.69 [0.42 to 1.14]).

CONCLUSIONS

Compared with insulin glargine, GLP-1 receptor agonists did not have a significant difference in regard to reducing HbA1c levels and they were significantly associated with decreased weight but increased gastrointestinal adverse events. It remains unclear whether GLP-1 receptor agonists influence mortality or diabetes-associated complications in patients with T2DM. More trials with longer follow-up are needed to determine the exact long-term efficacy and safety profiles of this new class of hypoglycemic drugs.

Pathophysiology and treatment of type 2 diabetes: perspectives on the past, present, and future

Glucose metabolism is normally regulated by a feedback loop including islet β cells and insulin-sensitive tissues, in which tissue sensitivity to insulin affects magnitude of β-cell response. If insulin resistance is present, β cells maintain normal glucose tolerance by increasing insulin output. Only when β cells cannot release sufficient insulin in the presence of insulin resistance do glucose concentrations rise. Although β-cell dysfunction has a clear genetic component, environmental changes play an essential part. Modern research approaches have helped to establish the important role that hexoses, aminoacids, and fatty acids have in insulin resistance and β-cell dysfunction, and the potential role of changes in the microbiome. Several new approaches for treatment have been developed, but more effective therapies to slow progressive loss of β-cell function are needed. Recent findings from clinical trials provide important information about methods to prevent and treat type 2 diabetes and some of the adverse effects of these interventions. However, additional long-term studies of drugs and bariatric surgery are needed to identify new ways to prevent and treat type 2 diabetes and thereby reduce the harmful effects of this disease.

Studies on the antidiabetic activities of Cordyceps militaris extract in diet-streptozotocin-induced diabetic Sprague-Dawley rats

Due to substantial morbidity and high complications, diabetes mellitus is considered as the third “killer” in the world. A search for alternative antidiabetic drugs from herbs or fungi is highly demanded. Our present study aims to investigate the antidiabetic activities of Cordyceps militaris on diet-streptozotocin-induced type 2 diabetes mellitus in rats. Diabetic rats were orally administered with water extract or alcohol extract at 0.05 g/kg and 2 g/kg for 3 weeks, and then, the factors levels related to blood glucose, lipid, free radicals, and even nephropathy were determined. Pathological alterations on liver and kidney were examined. Data showed that, similar to metformin, Cordyceps militaris extracts displayed a significant reduction in blood glucose levels by promoting glucose metabolism and strongly suppressed total cholesterol and triglycerides concentration in serum. Cordyceps militaris extracts exhibit antioxidative effects indicated by normalized superoxide dismutase and glutathione peroxidase levels. The inhibitory effects on blood urea nitrogen, creatinine, uric acid, and protein revealed the protection of Cordyceps militaris extracts against diabetic nephropathy, which was confirmed by pathological morphology reversion. Collectively, Cordyceps militaris extract, a safe pharmaceutical agent, presents excellent antidiabetic and antinephropathic activities and thus has great potential as a new source for diabetes treatment.

Cardiovascular safety and glycemic control of glucagon-like peptide-1 receptor agonists for type 2 diabetes mellitus: a pairwise and network meta-analysis

AIMS

Integrating evidence from all randomized controlled trials (RCTs) of glucagon-like peptide-1 receptor agonists (GLP-1s) to assess the safety of cardiovascular disease (CVD) and efficacy of glycemic control.

METHODS

Besides performing pairwise meta-analysis, network meta-analysis of all RCTs was used to combine direct and indirect estimates of the effect of GLP-1 with placebo, active comparator drugs (ACD), or another GLP-1 agent with treatment duration ≥8 weeks in T2DM patients, 15,883 for CVD safety from 45 RCTs and 14,136 for glycemic control from 36 RCTs.

RESULTS

For CVD safety, both of the results from pairwise and network meta-analysis failed to demonstrate significant difference between any two comparators. For glycemic control, the effect of any GLP-1 was better than placebo, but no difference was found between GLP-1s. We also found that liraglutide was the only GLP-1 drug shown to be more effective on improving glycemic control than ACD and exenatide. The results based on direct or indirect estimates were similar for two outcomes.

CONCLUSION

Our network meta-analysis provides a complete picture of the associations between GLP-1s, ACD and placebo on CVD safety and glycemic control. The GLP-1s are promising candidates for the treatment of T2DM, but more long-term trials are needed to confirm potential CVD safety.

Clinical pharmacology of alogliptin, a dipeptidyl peptidase-4 inhibitor, for the treatment of Type 2 diabetes

Alogliptin is a new, potent, highly selective, orally available inhibitor of the dipeptidyl peptidase-4 (DPP-4) enzyme developed for the treatment of Type 2 diabetes mellitus (T2DM). Inhibition of the DPP-4 enzyme, prevents the inactivation of the incretin hormones, glucagon-like peptide (GLP-1) and glucose-dependent insulinotropic peptide (GIP), both of which have very short half-lives. GLP-1 and GIP are released in response to food ingestion; they enhance nutrient-induced insulin secretion and inhibit postprandial glucagon secretion. The pharmacokinetics and pharmacodynamics of alogliptin are suitable for once-daily dosing. In two Phase I clinical trials, one in healthy subjects and one in early-diagnosed patients with T2DM, alogliptin has been shown to be safe and well tolerated. In a Phase II clinical trial, alogliptin was shown to be safe and demonstrated efficacy in patients with T2DM with a dose-response profile suitable for Phase III dose selection.

Prediabetes: to treat or not to treat?

The incidence of diabetes is continuously increasing worldwide. Pre-diabetes (defined as impaired glucose tolerance, impaired fasting glucose or both) represents an intermediate state, which often progresses to overt diabetes within a few years. In addition, pre-diabetes may be associated with increased risk of microvascular and macrovascular complications. Thus, reverting a pre-diabetic state as well as preventing the development of diabetes represents enormous challenge for the clinician. Lifestyle modification in pre-diabetic individuals was found particularly effective in the prevention of diabetes. However, compliance to lifestyle modification measures can be a crucial problem in the everyday clinical practice, especially in developing countries. During the last decade many studies support the use of anti-diabetic treatment schemes in pre-diabetic subjects to be advantageous. The American Diabetes Prevention Program (DPP) as well as other minor studies and meta-analyses has convincingly demonstrated the efficacy of metformin in this patient group. In addition, results of the 10 year DPP follow up have recently been published, demonstrating the long term safety and sustainability of metformin treatment benefits in this population. In contrast to metformin, the evidence from the use of other anti-diabetic agents (thiazolidinediones, a-glucosidase inhibitors, incretin mimetics) in pre-diabetic individuals is rather inadequate and prospective data is further needed. Furthermore, large scale studies with hard clinical endpoints are needed to delineate the effect of pre-diabetes treatment on macro- and microvascular complications. In conclusion, several strategies of patient management, mainly lifestyle modification and pharmacological interventions can prevent diabetes development in subjects diagnosed with pre-diabetes or even revert pre-diabetic state. However, whether this biochemical improvement can be translated into actual clinical benefit remains to be established.

Effect of mulberry leaf extract with enriched 1-deoxynojirimycin content on postprandial glycemic control in subjects with impaired glucose metabolism

Aims/Introduction:  The glucose analogue, 1-deoxynojirimycin (DNJ), found in mulberry (Morus alba) leaves, is a promising α-glucosidase inhibitor. We evaluated the effect of the ingestion of mulberry leaf extract with enriched DNJ content on postprandial hyperglycemia in subjects with impaired glucose metabolism.

MATERIALS AND METHODS

  In study 1, we carried out a randomized, double-blind, crossover trial to assess the effects of single ingestion of mulberry leaf extract (3, 6 or 9 mg DNJ) or placebo on blood glucose and insulin concentrations during 2 h after a carbohydrate (200 g boiled white rice) challenge in 12 subjects with fasting plasma glucose (FPG) in the range of 100-140 mg/dL. Study 2 was a randomized, double-blind, placebo-controlled trial to assess the efficacy of 12-week extract supplementation (6 mg DNJ, t.i.d.) for long-term glycemic control in 76 subjects with FPG in the range of 110-140 mg/dL.

RESULTS

  In study 1, ingestion of the mulberry leaf extract led to attenuated postchallenge acute glycemia in a dose-dependent manner (P = 0.006, group × time interaction, two-way anova). In study 2, the serum 1,5-anhydroglucitol concentration, a sensitive indicator of postprandial glycemic control, in the extract group increased and was higher than that in the placebo group over the 12-week treatment period (P < 0.001, group × time interaction, two-way anova); no differences in FPG, glycated hemoglobin and glycated albumin concentrations were observed between the groups.

CONCLUSIONS

  Long-term ingestion of mulberry leaf extract with enriched DNJ content could result in improved postprandial glycemic control in individuals with impaired glucose metabolism. These trials were registered with UMIN (no. UMIN000003154 and UMIN000003155). (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00101.x, 2011).

Oral anti-diabetic drugs for the prevention of Type 2 diabetes

AIM

To determine the comparative efficacy of oral anti-diabetic drugs in preventing the development of Type 2 diabetes.

METHODS

A systematic literature search of MEDLINE, EMBASE and Cochrane CENTRAL was conducted for randomized controlled trials evaluating oral anti-diabetic drugs in patients at high risk for developing Type 2 diabetes. Mixed-treatment comparison meta-analysis methods were used to evaluate the relative risks and risk differences of developing Type 2 diabetes, along with associated 95% credible intervals.

RESULTS

Overall, 20 trials (n = 23 230 participants) were included. Upon mixed-treatment comparison meta-analysis, thiazolidinediones, alpha-glucosidase inhibitors and biguanides significantly reduced the relative risk of developing diabetes by 64, 40 and 27%, respectively, compared with control. Sulphonylureas and glinides showed no significant effect. Moreover, thiazolidinediones significantly reduced the relative risk of diabetes by 50% compared with biguanides and trended towards a 40% risk reduction vs. alpha-glucosidase inhibitors [relative risk 0.60 (95% credible intervals 0.34-1.02)]. None of the results were appreciably altered upon subgroup or sensitivity analyses. When evaluating risk differences compared with control, thiazolidinediones (-9%, number needed to treat = 11), alpha-glucosidase inhibitors (-7%, number needed to treat = 14) and biguanides (-7%, number needed to treat = 14) continued to show significant benefit.

CONCLUSIONS

Of the oral anti-diabetic drugs evaluated to prevent Type 2 diabetes, thiazolidinediones were associated with the greatest risk reduction compared with control and associated with greater risk reduction than biguanides. Alpha-glucosidase inhibitors and biguanides performed similarly, and better than control, while sulphonylureas and glinides provided no significant benefit.

Type 2 diabetes across generations: from pathophysiology to prevention and management

Type 2 diabetes is now a pandemic and shows no signs of abatement. In this Seminar we review the pathophysiology of this disorder, with particular attention to epidemiology, genetics, epigenetics, and molecular cell biology. Evidence is emerging that a substantial part of diabetes susceptibility is acquired early in life, probably owing to fetal or neonatal programming via epigenetic phenomena. Maternal and early childhood health might, therefore, be crucial to the development of effective prevention strategies. Diabetes develops because of inadequate islet β-cell and adipose-tissue responses to chronic fuel excess, which results in so-called nutrient spillover, insulin resistance, and metabolic stress. The latter damages multiple organs. Insulin resistance, while forcing β cells to work harder, might also have an important defensive role against nutrient-related toxic effects in tissues such as the heart. Reversal of overnutrition, healing of the β cells, and lessening of adipose tissue defects should be treatment priorities.

Low-dose combination therapy with rosiglitazone and metformin to prevent type 2 diabetes mellitus (CANOE trial): a double-blind randomised controlled study

BACKGROUND

The evolving epidemic of type 2 diabetes has challenged health-care providers to assess the safety and efficacy of various diabetes prevention strategies. The CANOE (CAnadian Normoglycemia Outcomes Evaluation) trial investigated whether low-dose combination therapy would affect development of type 2 diabetes.

METHODS

In this double-blind, randomised controlled trial undertaken in clinics in Canadian centres, 207 patients with impaired glucose tolerance were randomly assigned to receive combination rosiglitazone (2 mg) and metformin (500 mg) twice daily or matching placebo for a median of 3.9 years (IQR 3.0-4.6). Randomisation was computer-generated in blocks of four, with both participants and investigators masked to treatment allocation. The primary outcome was time to development of diabetes, measured by an oral glucose tolerance test or two fasting plasma glucose values of 7.0 mmol/L or greater. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00116932.

FINDINGS

103 participants were assigned to rosiglitazone and metformin, and 104 to placebo; all were analysed. Vital status was obtained in 198 (96%) participants, and medication compliance (taking at least 80% of assigned medication) was 78% (n=77) in the metformin and rosiglitazone group and 81% (n=80) in the placebo group. Incident diabetes occurred in significantly fewer individuals in the active treatment group (n=14 [14%]) than in the placebo group (n=41 [39%]; p<0.0001). The relative risk reduction was 66% (95% CI 41-80) and the absolute risk reduction was 26% (14-37), yielding a number needed to treat of 4 (2.70-7.14). 70 (80%) patients in the treatment group regressed to normal glucose tolerance compared with 52 (53%) in the placebo group (p=0.0002). Insulin sensitivity decreased by study end in the placebo group (median -1.24, IQR -2.38 to -0.08) and remained unchanged with rosiglitazone and metformin treatment (-0.39, -1.30 to 0.84; p=0.0006 between groups). The change in beta-cell function, as measured by the insulin secretion-sensitivity index-2, did not differ between groups (placebo -252.3, -382.2 to -58.0 vs rosiglitazone and metformin -221.8, -330.4 to -87.8; p=0.28). We recorded an increase in diarrhoea in participants in the active treatment group compared with the placebo group (16 [16%] vs 6 [6%]; p=0.0253).

INTERPRETATION

Low-dose combination therapy with rosiglitazone and metformin was highly effective in prevention of type 2 diabetes in patients with impaired glucose tolerance, with little effect on the clinically relevant adverse events of these two drugs.

FUNDING

GlaxoSmithKline.

Regulation effects on abnormal glucose and lipid metabolism of TZQ-F, a new kind of Traditional Chinese Medicine

AIM OF THE STUDY

Based on the recipe of the traditional anti-diabetic formula TZQ, we developed TZQ-F, a new formula including 8 fractions isolated from Red Paeony root, Mulberry leaf, Lotus leaf, Danshen root and Hawthorn leaf with a good quality assurance. The study was aimed at fraction preparation and effects of the fractions on abnormal glucose and lipid metabolism.

MATERIALS AND METHODS

The active fractions were obtained by macroporous resin, ion-exchange resin and polyamide resin column chromatographies. HPLC analyses were used for quality control. In vitro mechanism study included DPPH radical scavenging, AGEs formation inhibition, alpha-glucosidase inhibition and lipase inhibition, and rats on high-fat diet were used for in vivo study.

RESULTS

In vitro mechanism study showed that among the 8 fractions, three of them had inhibition effects on intestinal disaccharase, three with inhibition effects on lipase, and five with effects of free radical scavenging. In vivo study showed that after 4 weeks of treatment, TZQ-F significantly decreased the levels of serum total cholesterol, TG, glucose, LDL-C and HDL-C in rats on high-fat diet. Consistent with the in vitro and in vivo results, histology study demonstrated that TZQ-F alleviated hepatic steatosis induced by high-fat diet.

CONCLUSIONS

TZQ-F possesses the potential regulation effects on abnormal glucose and lipid metabolism.

Asymmetric synthesis of tetrabenazine and dihydrotetrabenazine

The enantioselective synthesis of (+)-tetrabenazine (TBZ) and (+)-dihydrotetrabenazine (DTBZ), agents of significant interest for therapeutic and molecular imaging applications, has been completed in 21% (TBZ) and 16% (DTBZ) overall yield and in >97% ee from the starting dihydroisoquinoline. The synthesis utilizes Sodeoka's palladium-catalyzed asymmetric malonate addition to set the initial stereocenter followed by a number of diastereoselective transformations to incorporate the remaining asymmetric centers.

Combining a dipeptidyl peptidase-4 inhibitor, alogliptin, with pioglitazone improves glycaemic control, lipid profiles and beta-cell function in db/db mice

BACKGROUND AND PURPOSE

Alogliptin, a highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor, enhances incretin action and pioglitazone enhances hepatic and peripheral insulin actions. Here, we have evaluated the effects of combining these agents in diabetic mice.

EXPERIMENTAL APPROACH

Effects of short-term treatment with alogliptin alone (0.01%-0.1% in diet), and chronic combination treatment with alogliptin (0.03% in diet) and pioglitazone (0.0075% in diet) were evaluated in db/db mice exhibiting early stages of diabetes.

KEY RESULTS

Alogliptin inhibited plasma DPP-4 activity up to 84% and increased plasma active glucagon-like peptide-1 by 4.4- to 4.9-fold. Unexpectedly, alogliptin alone lacked clear efficacy for improving glucose levels. However, alogliptin in combination with pioglitazone clearly enhanced the effects of pioglitazone alone. After 3-4 weeks of treatment, combination treatment increased plasma insulin by 3.8-fold, decreased plasma glucagon by 41%, both of which were greater than each drug alone, and increased plasma adiponectin by 2.4-fold. In addition, combination treatment decreased glycosylated haemoglobin by 2.2%, plasma glucose by 52%, plasma triglycerides by 77% and non-esterified fatty acids by 48%, all of which were greater than each drug alone. Combination treatment also increased expression of insulin and pancreatic and duodenal homeobox 1 (PDX1), maintained normal beta-cell/alpha-cell distribution in islets and restored pancreatic insulin content to levels comparable to non-diabetic mice.

CONCLUSIONS AND IMPLICATIONS

These results indicate that combination treatment with alogliptin and pioglitazone at an early stage of diabetes improved metabolic profiles and indices that measure beta-cell function, and maintained islet structure in db/db mice, compared with either alogliptin or pioglitazone monotherapy.

Use of cannabinoid CB1 receptor antagonists for the treatment of metabolic disorders

Abdominal obesity is associated with numerous metabolic abnormalities, including insulin resistance, impaired glucose tolerance/type-2 diabetes, and atherogenic dyslipidaemia with low high-density lipoprotein (HDL) cholesterol, high triglycerides, and increased small dense low-density lipoprotein (LDL) cholesterol. A proportion of these metabolic disorders may be attributed to increased endocannabinoid activity. The selective cannabinoid 1 (CB1) receptor antagonist rimonabant has been shown to reduce body weight, waist circumference, insulin resistance, triglycerides, dense LDL, C-reactive protein (CRP), and blood pressure, and to increase HDL and adiponectin concentrations in both non-diabetic and diabetic overweight/obese patients. Besides an improvement in glucose tolerance in non-diabetic subjects, a reduction of 0.5-0.7% in haemoglobin A1C (HbA(1c)) levels was consistently observed in various groups of patients with type-2 diabetes. Almost half the metabolic changes could not be explained by weight loss, supporting direct peripheral effects of rimonabant. Ongoing studies should demonstrate whether improved metabolic disorders with CB1 receptor antagonists (rimonabant, taranabant, etc.) would translate into fewer cardiovascular complications among high-risk individuals.

Dysglycaemia in non-diabetic hypertensive patients: comparison of the impact of two different classifications of impaired fasting glucose on the cardiovascular risk profile

The clinical correlates and risk profile of prediabetes (fasting plasma glucose (FPG) values in the upper normal limits but below the diabetic threshold) in hypertension, an insulin-resistant, prodiabetogenic condition, are scarcely known. For this reason, we evaluated 982 non-diabetic (FPG,<126 mg 100 ml(-1) and no antidiabetic treatment) referred hypertensive patients without a history of cardiovascular disease grouped by mild (100-109 mg 100 ml(-1)) and advanced (110-125 mg 100 ml(-1)) dysglycaemia compared with normal FPG (<100 mg 100 ml(-1)). FPG, total and high density lipoprotein (HDL) cholesterol, triglycerides and total white blood cell count were assessed by standard methodologies; 10-year predicted coronary heart disease (CHD) risk was approximated by the Framingham risk score (FRS). Metabolic syndrome (MetS) was diagnosed by standard categorical criteria using either 110 or 100 mg 100 ml(-1) as a threshold for impaired fasting glucose (IFG). FPG was above 110 in 13% and between 100 and 109 in 20% of patients. In both dysglycaemic groups, perturbed glucose homeostasis was associated with abnormally high fasting triglycerides, low HDL cholesterol, obesity, worse CHD risk profile and higher white blood cell count. MetS was highly prevalent and its distribution pattern was markedly influenced by the definitions of IFG based on different FPG cutoffs. Thus, even mildly perturbed glucose homeostasis associates with atherogenic dyslipidaemia, obesity and adverse risk profile in non-diabetic hypertensive patients. Because of its prediabetic nature, dysglycaemia should prompt measures to prevent new-onset diabetes, although the role of IFG as an independent risk factor awaits specifically designed intervention trials.

Cannabinoid-1 receptor antagonists in type-2 diabetes

Type-2 diabetes is closely related to abdominal obesity and is generally associated with other cardiometabolic risk factors, resulting in a risk of major cardiovascular disease. Several animal and human observations suggest that the endocannabinoid system is over-active in the presence of abdominal obesity and/or diabetes. Both central and peripheral endocannabinoid actions, via the activation of CB1 receptors, promote weight gain and associated metabolic changes. Rimonabant, the first selective CB(1) receptor blocker in clinical use, has been shown to reduce body weight, waist circumference, triglycerides, blood pressure, insulin resistance index and C-reactive protein levels, and to increase high-density lipoprotein (HDL) cholesterol and adiponectin concentrations in both non-diabetic and diabetic overweight/obese patients. In addition, a 0.5-0.7% reduction in HbA1c levels was observed in metformin- or sulphonylurea-treated patients with type-2 diabetes and in drug-naïve diabetic patients. Almost half of the metabolic changes, including HbA1c reduction, could not be explained by weight loss, suggesting that there are direct peripheral effects. Rimonabant was generally well-tolerated, and the safety profile was similar in diabetic and non-diabetic patients, with a higher incidence of depressed mood disorders, nausea and dizziness. In conclusion, the potential role of rimonabant in overweight/obese patients with type-2 diabetes and at high risk of cardiovascular disease deserves much consideration.