Effect of Rosiglitazone and Ramipril on {beta}-cell function in people with impaired glucose tolerance or impaired fasting glucose: the DREAM trial

Angiotensin-Converting-Enzyme 2 and Renin-Angiotensin System Inhibitors in COVID-19: An Update

Ever since its outbreak, Corona Virus Disease 2019(COVID-19) caused by SARS-CoV-2 has affected more than 26 million individuals in more than 200 countries. Although the mortality rate of COVID-19 is low, but several clinical studies showed, patients with diabetes mellitus (DM) or other major complication at high risk of COVID-19 and reported more severe disease and increased fatality. The angiotensin-converting-enzyme 2 (ACE2), a component of renin-angiotensin-system (RAS); acts on ACE/Ang-II/AT1recptor axis, and regulates pathological processes like hypertension, cardiac dysfunction, Acute Respiratory Distress Syndrome (ARDS) etc. The progression of T2DM and hypertension show decreased expression and activity of ACE2. There are several treatment strategies for controlling diabetes, hypertension, etc; like ACE2 gene therapies, endogenous ACE2 activators, human recombinant ACE2 (hrACE2), Angiotensin-II receptor blockers (ARBs) and ACE inhibitors (ACEi) medications. ACE2, the receptors for SARS-CoV2, facilitates virus entry inside host cell. Clinicians are using two classes of medications for the treatment of COVID-19; one targets the SARS-CoV-2-ACE2 interaction, while other targets human immune system. The aim of this review is to discuss the role of ACE2 in diabetes and in COVID-19 and to provide an analysis of data proposing harm and benefit of RAS inhibitor treatment in COVID-19 infection as well as showing no association whatsoever. This review also highlights some candidate vaccines which are undergoing clinical trials.

Dual GIP and GLP-1 Receptor Agonist Tirzepatide Improves Beta-cell Function and Insulin Sensitivity in Type 2 Diabetes

CONTEXT

Novel dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist (RA) tirzepatide demonstrated substantially greater glucose control and weight loss (WL) compared with selective GLP-1RA dulaglutide.

OBJECTIVE

Explore mechanisms of glucose control by tirzepatide.

DESIGN

Post hoc analyses of fasting biomarkers and multiple linear regression analysis.

SETTING

Forty-seven sites in 4 countries.

PATIENTS OR OTHER PARTICIPANTS

Three hundred and sixteen subjects with type 2 diabetes.

INTERVENTIONS

Tirzepatide (1, 5, 10, 15 mg), dulaglutide (1.5 mg), placebo.

MAIN OUTCOME MEASURES

Analyze biomarkers of beta-cell function and insulin resistance (IR) and evaluate WL contributions to IR improvements at 26 weeks.

RESULTS

Homeostatic model assessment (HOMA) 2-B significantly increased with dulaglutide and tirzepatide 5, 10, and 15 mg compared with placebo (P ≤ .02). Proinsulin/insulin and proinsulin/C-peptide ratios significantly decreased with tirzepatide 10 and 15 mg compared with placebo and dulaglutide (P ≤ .007). Tirzepatide 10 and 15 mg significantly decreased fasting insulin (P ≤ .033) and tirzepatide 10 mg significantly decreased HOMA2-IR (P = .004) compared with placebo and dulaglutide. Markers of improved insulin sensitivity (IS) adiponectin, IGFBP-1, and IGFBP-2 significantly increased by 1 or more doses of tirzepatide (P < .05). To determine whether improvements in IR were directly attributable to WL, multiple linear regression analysis with potential confounding variables age, sex, metformin, triglycerides, and glycated hemoglobin A1c was conducted. WL significantly (P ≤ .028) explained only 13% and 21% of improvement in HOMA2-IR with tirzepatide 10 and 15 mg, respectively.

CONCLUSIONS

Tirzepatide improved markers of IS and beta-cell function to a greater extent than dulaglutide. IS effects of tirzepatide were only partly attributable to WL, suggesting dual receptor agonism confers distinct mechanisms of glycemic control.

Postintervention Effects of Varying Treatment Arms on Glycemic Failure and β-Cell Function in the TODAY Trial

OBJECTIVE

The Treatment Options for type 2 Diabetes in Adolescents and Youth (TODAY) trial demonstrated that glycemic failure rates were significantly lower in youth randomized to metformin plus rosiglitazone treatment than in youth randomized to metformin alone or metformin plus intensive lifestyle intervention. At the end of the study, rosiglitazone was permanently discontinued, and routine diabetes care resumed. Herein, we report postintervention glycemic failure rates in TODAY participants over an additional 36 months of follow-up for the three original treatment arms and describe insulin sensitivity and β-cell function outcomes.

RESEARCH DESIGN AND METHODS

A total of 699 participants were randomized during TODAY, of whom 572 enrolled in the TODAY2 observational follow-up. Glycemic failure was defined as HbA1c ≥8% over a 6-month period, inability to wean from temporary insulin therapy within 3 months after acute metabolic decompensation during TODAY, or sustained HbA1c ≥8% over two consecutive visits during TODAY2. Oral glucose tolerance tests were conducted, and insulin sensitivity, insulinogenic index, and oral disposition index were calculated.

RESULTS

During the 36 months of TODAY2, glycemic failure rates did not differ among participants by original treatment group assignment. Insulin sensitivity and β-cell function deteriorated rapidly during the 36 months of TODAY2 routine diabetes care but did not differ by treatment group assignment.

CONCLUSIONS

The added benefit of preventing glycemic failure by using rosiglitazone as a second agent in youth-onset type 2 diabetes did not persist after its discontinuation. More work is needed to address this rapid progression to avoid long-term diabetes complications.

The Natural Course of Impaired Fasting Glucose

Impaired glucose regulation, including diabetes and prediabetes, poses a huge global problem not only in health but also in the epidemiological and economic areas. These disorders are often detected too late or remain unrecognized. The article aims to provide a review of the prevalence, etiology, and natural history of impaired fasting glucose (IFG). We focus on the progression of isolated IFG to full-fledged type 2 diabetes and the factors conducive to the development of diabetes. The knowledge about it could help design an optimal management program for the prevention of diabetes in patients with IFG; a program that would be patient-tailored and based on the underlying pathophysiology.

Efficacy and safety of Rhizoma curcumea longae with respect to improving the glucose metabolism of patients at risk for cardiovascular disease: a meta-analysis of randomised controlled trials

BACKGROUND

Clinical evidence suggests that curcuminoids, as a natural polyphenol, can provide support for cardioprotection and glucose metabolism. This meta-analysis assessed the efficacy and safety of curcumin with respect to improving glucose metabolism in patients with cardiovascular risk factors.

METHODS

Four databases (PubMed, Cochrane Library, Web of Science and Embase) were searched up to June 2018. The inclusion criteria included (i) randomised controlled trials (RCT) and (ii) subjects with risk factors for cardiovascular disease supplemented with curcumin and curcuminoids. A random-effects model and a standardised mean difference with a 95% confidence interval were used to perform quantitative data synthesis. Sensitivity and subgroup analyses were conducted to assess the effects.

RESULTS

Fourteen eligible RCT with 1277 subjects were included. In the overall analyses, curcumin led to significant decreases in fasting blood glucose (FBG), glycated haemoglobin (HbA1c) and homeostatic model assessment of insulin resistance (HOMA-IR). The subgroup analyses suggested that curcumin or combined curcuminoids were more effective at reducing FBG and HbA1c in type 2 diabetes patients than in individuals with metabolic syndrome. Supplementation with curcuminoids at doses ≥300 mg day^-1 showed significant decreases in FBG, HbA1c and HOMA-IR. The effects of supplementation on FBG, HbA1c and HOMA-IR were more significant over long periods (≥12 weeks) than short periods. Curcumin and curcuminoids were well tolerated, with no serious adverse events.

CONCLUSIONS

Curcumin or combined curcuminoids could exert cardioprotective effects in patients at risk for cardiovascular disease by improving glucose metabolism. However, further high-quality studies and larger sample sizes are required to confirm these results.

Age-related diseases as vicious cycles

The mortality rates of age-related diseases (ARDs) increase exponentially with age. Processes described by the exponential growth function typically involve a branching chain reaction or, more generally, a positive feedback loop. Here I propose that each ARD is mediated by one or several positive feedback loops (vicious cycles). I then identify critical vicious cycles in five major ARDs: atherosclerosis, hypertension, diabetes, Alzheimer's and Parkinson's. I also propose that the progression of ARDs can be halted by selectively interrupting the vicious cycles and suggest the most promising targets.

Pharmaceutical Interventions for Diabetes Prevention in Patients at Risk

With the rising incidence and prevalence rates of type 2 diabetes globally, it is imperative that diabetes prevention strategies are implemented to stem the flow of new cases. Successful interventions include both lifestyle modification and pharmaceutical agents, and large, multicentre, randomised, controlled studies in different populations have identified the benefits of both. However, translating positive trial outcomes to the real world is particularly challenging, as lifestyle interventions require regular reinforcement from healthcare professionals to be maintained. Pharmaceutical therapies may therefore play an adjunctive role in combination with lifestyle to prevent diabetes. Population-based strategies are also necessary to reduce sedentary behaviour and obesity. Well-established glucose-lowering therapies such as metformin, sulphonylureas, thiazolidinediones and insulin and newer agents such as incretin therapies and sodium glucose co-transporter 2 inhibitors have all been investigated in randomised controlled trials for diabetes prevention with varying success. Non-glucose-lowering therapies such as orlistat and renin angiotensin system blockers can prevent diabetes, whereas statins are associated with slightly increased risk. Diabetes prevention strategies should carefully consider the use of these agents according to individual patient circumstances and phenotypic profile.

Decreased diabetes risk over 9 year after 18-month oral L-arginine treatment in middle-aged subjects with impaired glucose tolerance and metabolic syndrome (extension evaluation of L-arginine study)

Purpose

This study aimed to determine whether l-arginine supplementation lasting for 18 months maintained long-lasting effects on diabetes incidence, insulin secretion and sensitivity, oxidative stress, and endothelial function during 108 months among subjects at high risk of developing type 2 diabetes.

Methods

One hundred and forty-four middle-aged subjects with impaired glucose tolerance and metabolic syndrome were randomized in 2006 to an l-arginine supplementation (6.4 g orally/day) or placebo therapy lasting 18 months. This period was followed by a 90-month follow-up. The primary outcome was a diagnosis of diabetes during the 108 month study period. Secondary outcomes included changes in insulin secretion (proinsulin/c-peptide ratio), insulin sensitivity (IGI/HOMA-IR), oxidative stress (AOPPs), and vascular function. After the 18 month participation, subjects that were still free of diabetes and willing to continue their participation (104 subjects) were further followed until diabetes diagnosis, with a time span of about 9 years from baseline.

Results

Although results derived from the 18 month of the intervention study demonstrated no differences in the probability of becoming diabetics, at the end of the study, the cumulative incidence of diabetes was of 40.6% in the l-arginine group and of 57.4% in the placebo group. The adjusted HR for diabetes (l-arginine vs. placebo) was 0.66; 95% CI 0.48, 0.91; p < 0.02). Proinsulin/c-peptide ratio (p < 0.001), IGI/HOMA-IR (p < 0.01), and AOPP (p < 0.05) levels were ameliorated in l-arginine compared to placebo.

Conclusions

These results may suggest that the administration of l-arginine could delay the development of T2DM for a long period. This effect could be mediated, in some extent, by l-arginine-induced reduction in oxidative stress.

Dihydromyricetin delays the onset of hyperglycemia and ameliorates insulin resistance without excessive weight gain in Zucker diabetic fatty rats

Many flavonoids are reported to be partial agonists of PPARγ and exert antidiabetic effects with fewer side effects compared with full agonists. Here, we assessed the effects of flavonoid dihydromyricetin (DHM) on glucose homeostasis in male Zucker diabetic fatty rats. Animals were treated with DHM (50-200  mg kg^-1) or rosiglitazone (4  mg kg^-1) once a day for 8 weeks. We found that DHM reduced fasting blood glucose and delayed the onset of hyperglycemia by 4 weeks. Furthermore, DHM preserved pancreatic β-cell mass, elevated adiponectin and improved lipid profile more vigorously than rosiglitazone. Notably, DHM decreased body weight gain and fat accumulation in both liver and adipose tissue, while rosiglitazone caused a significant increase of body weight and fat accumulation. DHM inhibited phosphorylation of PPARγ at serine 273 more efficiently than rosiglitazone. These results suggest that DHM exerts antidiabetic effects without causing excessive body weight gain via inhibition of PPARγ phosphorylation.

Depression mediates impaired glucose tolerance and cognitive dysfunction: A neuromodulatory role of rosiglitazone

Comorbidity of depression and diabetes is a serious risk factor worsening the complications such as cognitive function and locomotion. Treatment under this condition becomes extremely complicated. Insulin signaling and autophagy pathways are involved in modulation of learning and memory. Rosiglitazone (ROSI) ameliorate cognitive deficit associated with depression and insulin resistance. In the present study, we investigated the effect of ROSI against chronic unpredictable stress (CUS) induced depression as a risk factor for diabetes and behavioral dysfunctions. Adult male Swiss albino mice were exposed to CUS alongside ROSI (5mg/kg/day) treatment for 21days. Thereafter, animals were subjected to different behavioral studies to assess depressive like behavior, cognition and locomotion. The effect of ROSI on insulin signaling, autophagy and apoptosis were evaluated in the hippocampus. CUS resulted in depressive like behavior, cognitive impairment and hypolocomotion associated with oxidative stress, impaired glucose tolerance and hypercorticosteronemia. CUS significantly impaired hippocampal insulin signaling, membrane translocation of glucose transporter type 4 (GLUT4) as well as decreased the expression of autophagy5, autophagy7, B-cell lymphoma 2 and apoptosis inhibitory protein 2. ROSI significantly reduced depressive like behavior, postprandial blood glucose, hypercorticosteronemia, oxidative and inflammatory stress, and apoptosis in stressed mice. Moreover, ROSI treatment effectively improved hippocampal insulin signaling, GLUT4 membrane translocation and cognitive performance in depressed mice. ROSI administration might prove to be effective for neurological disorders associated with depressive like behavior and impaired glucose tolerance.

Pharmacogenetic influence of eNOS gene variant on endothelial and glucose metabolism responses to L-arginine supplementation: Post hoc analysis of the L-arginine trial

OBJECTIVE

To evaluate whether variants of the eNOS gene are associated with endothelial and metabolic responses to L-arginine (L-arg) supplementation.

MATERIAL AND METHODS

We examined a single nucleotide polymorphism of the eNOS gene (rs753482-A>C) to investigate the effects of this variant on endothelial function (EF), colony-forming unit-endothelial cell (CFU-EC) number, asymmetric-dimethylarginine (ADMA) level, insulin sensitivity index (ISI), and insulin secretion (IS) in a post hoc analysis of the L-arg trial. The L-arg trial (6.4 g/day for 18 months) was a single-center, randomized, double-blind, parallel-group, placebo-controlled, phase III trial in individuals with impaired glucose tolerance and metabolic syndrome. followed by a 12-month extended follow-up period after termination of the study drug (NCT 00917449).

RESULTS

At baseline, EF, CFU-EC numbers, ADMA levels, and ISI were impaired in subjects carrying minor allele C (both heterozygotes, AC and homozygotes, CC) as compared to subjects carrying major allele A (homozygotes, AA) (p<0.01). Compared to placebo, L-arg increased EF, CFU-EC numbers, and ISI, and improved ADMA levels and IS (p<0.01). The greatest improvements were found in AA subjects treated with L-arg, while the worst results were found in AC+CC subjects treated with placebo. In the placebo-treated subjects, EF, CFU-EC, ISI, and IS were significantly lower and ADMA was significantly higher in AC+CC subjects than in AA subjects.

CONCLUSIONS

Treatment with L-arg induced similar improvements in EF, CFU-EC numbers, ADMA levels, ISI, and IS in both AA subjects and AC+CC subjects. The presence of minor allele resulted in the worst prognosis in terms of EF, CFU-EC numbers, ADMA levels, ISI, and IS during the 30-month observation period.

Role of Fenugreek in the prevention of type 2 diabetes mellitus in prediabetes

Background

It is hypothesized that dietary supplementation with Fenugreek modulates glucose homeostasis and potentially prevents diabetes mellitus in people with prediabetes. The objective of present study is to determine whether Fenugreek can prevent the outcome of T2DM in non diabetic people with prediabetes.

Methods

A 3-year randomized, controlled, parallel study for efficacy of Fenugreek (n = 66) and matched controls (n = 74) was conducted in men and women aged 30–70 years with criteria of prediabetes. Fenugreek powder, 5 g twice a day before meals, was given to study subjects and progression of type 2 diabetes mellitus (T2DM) was monitored at baseline and every 3 months for the 3-year study.

Results

By the end of intervention period, cumulative incidence rate of diabetes reduced significantly in Fenugreek group when compared to controls. The Fenugreek group also saw a significant reduction in fasting plasma glucose (FPG), postprandial plasma glucose (PPPG) and low density lipoprotein cholesterol (LDLc) whereas serum insulin increased significantly. It was observed that controls had 4.2 times higher chance of developing diabetes compared to subjects in the Fenugreek group. The outcome of diabetes in Fenugreek group was positively associated with serum insulin and negatively associated with insulin resistance (HOMA IR).

Conclusions

Dietary supplementation of 10 g Fenugreek/day in prediabetes subjects was associated with lower conversion to diabetes with no adverse effects and beneficial possibly due to its decreased insulin resistance.

Efficacy and safety of autologous bone marrow-derived stem cell transplantation in patients with type 2 diabetes mellitus: a randomized placebo-controlled study

There is a growing interest in cell-based therapies in T2DM as β-cell failure is progressive and inexorable with the advancing duration of disease. This prospective, randomized, single-blinded placebo-controlled study evaluates the efficacy and safety of autologous bone marrow-derived stem cell transplantation (ABMSCT) in T2DM. Twenty-one patients with triple oral antidiabetic drug failure and requiring insulin ≥0.4 IU per kg per day with HbA1c <7.5% were randomly assigned to an intervention (n = 11) and control group (n = 10) and followed for 12 months. Patients in the intervention group received ABMSCT through a targeted approach, and after 12 weeks, a second dose of stem cells was administered through the antecubital vein after mobilization with G-CSF, while the control group underwent a sham procedure. The primary end point was a reduction in insulin requirement by ≥50% from baseline while maintaining HbA1c <7%. Nine out of the 11 (82%) patients in the intervention group achieved the primary end point, whereas none of the patients in the control group did over the study period (p = 0.002). The insulin requirement decreased by 66.7% in the intervention group from 42.0 (31.0‐64.0) IU per day to 14.0 (0.0‐30.0) IU per day (p = 0.011), while in controls it decreased by 32.1% from 40.5 (31.8‐44.3) IU per day to 27.5 (23.5‐33.3) IU per day (p = 0.008) at 12 months. The reduction in insulin requirement was significantly more in the intervention group compared to controls at both 6 (p = 0.001) and 12 months (p = 0.004). There was a modest but nonsignificant increase in HbA1c (%) in cases from 6.9% (6.4‐7.2%) to 7.1% (6.6‐7.5%) as well as in controls from 6.9% (6.2‐7.0%) to 7.0% (6.9‐7.5%). Ten out of 11 (91%) patients could maintain HbA1c <7% in the intervention group, whereas 6 out of 10 did (60%) in the control group (p = 0.167). The glucagon-stimulated C-peptide significantly increased in treated cases compared to controls (p = 0.036). The decrease in insulin requirement positively correlated with stimulated C-peptide (r = 0.8, p = 0.001). In conclusion, ABMSCT results in a significant decrease in the insulin dose requirement along with an improvement in the stimulated C-peptide levels in T2DM. However, a greater number of patients with a longer duration of follow-up are required to substantiate these observations.

Effects of the polyphenol content on the anti-diabetic activity of Cinnamomum zeylanicum extracts

Cinnamomum zeylanicum is a popular kitchen spice widely investigated for insulin potentiating effects. Though a group of water soluble polyphenols belonging to the oligomeric procyanidins has been identified as the bioactive principle, the lack of systematic information on the effect of the polyphenol content on safety and anti-diabetic efficacy remains as a major limitation for the development of optimized and standardized cinnamon extracts for functional use. In the present paper, water soluble extracts of Cinnamomum zeylanicum containing 45 and 75% gallic acid equivalents (GAE) of polyphenol content were prepared by a novel process and characterized by tandem mass spectrometry. The polyphenol enhanced extracts were shown to be safe and offered better antioxidant potential, hypoglycemic effect, hypolipidimic effect, and significant decrease in other biochemical parameters as compared to the standard aqueous extract containing 15% GAE, when administered to streptozotocin-induced diabetic rats at 200 mg per kg b.w. for 30 days. The efficacy of polyphenol extracts in lowering blood glucose levels and ameliorating oxidative stress was further demonstrated in humans by administrating 'procynZ-45' containing 45% GAE polyphenols at a relatively low dosage of (125 mg × 2) per day for 30 days to 15 volunteers who had elevated fasting blood glucose levels; but not involved in any medication.

Pancreatic beta cell function following liraglutide-augmented weight loss in individuals with prediabetes: analysis of a randomised, placebo-controlled study

AIMS/HYPOTHESIS

Liraglutide can modulate insulin secretion by directly stimulating beta cells or indirectly through weight loss and enhanced insulin sensitivity. Recently, we showed that liraglutide treatment in overweight individuals with prediabetes (impaired fasting glucose and/or impaired glucose tolerance) led to greater weight loss (-7.7% vs -3.9%) and improvement in insulin resistance compared with placebo. The current study evaluates the effects on beta cell function of weight loss augmented by liraglutide compared with weight loss alone.

METHODS

This was a parallel, randomised study conducted in a single academic centre. Both participants and study administrators were blinded to treatment assignment. Individuals who were 40-70 years old, overweight (BMI 27-40 kg/m(2)) and with prediabetes were randomised (via a computerised system) to receive liraglutide (n = 35) or matching placebo (n = 33), and 49 participants were analysed. All were instructed to follow an energy-restricted diet. Primary outcome was insulin secretory function, which was evaluated in response to graded infusions of glucose and day-long mixed meals.

RESULTS

Liraglutide treatment (n = 24) significantly (p ≤ 0.03) increased the insulin secretion rate (% mean change [95% CI]; 21% [12, 31] vs -4% [-11, 3]) and pancreatic beta cell sensitivity to intravenous glucose (229% [161, 276] vs -0.5% (-15, 14]), and decreased insulin clearance rate (-3.5% [-11, 4] vs 8.2 [0.2, 16]) as compared with placebo (n = 25). The liraglutide-treated group also had significantly (p ≤ 0.03) lower day-long glucose (-8.2% [-11, -6] vs -0.1 [-3, 2]) and NEFA concentrations (-14 [-20, -8] vs -2.1 [-10, 6]) following mixed meals, whereas day-long insulin concentrations did not significantly differ as compared with placebo. In a multivariate regression analysis, weight loss was associated with a decrease in insulin secretion rate and day-long glucose and insulin concentrations in the placebo group (p ≤ 0.05), but there was no association with weight loss in the liraglutide group. The most common side effect of liraglutide was nausea.

CONCLUSIONS/INTERPRETATION

A direct stimulatory effect on beta cell function was the predominant change in liraglutide-augmented weight loss. These changes appear to be independent of weight loss.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01784965 FUNDING: The study was funded by the ADA.

Choice of early treatment regimen and impact on β-cell preservation in type 2 diabetes

The progressive deterioration of glycaemic control in individuals with type 2 diabetes mellitus (T2DM) results from insulin resistance combined with the ongoing loss of β-cell function. Although it had been suggested that most β-cell dysfunction occurs after the development of T2DM, studies have documented a substantial early loss of β-cell function, particularly during the prediabetic state. In patients diagnosed with T2DM, β-cell function continues to decline despite treatment with commonly prescribed antihyperglycaemic medications, and ultimately exogenous insulin administration is required to maintain optimal glycaemic control. Thus, interventions to address the early decline in β-cell function could potentially alter the course of T2DM, preventing or delaying its onset and decreasing the incidence of complications. Original research and review articles on this topic were identified in a PubMed search from January 2000 through August 2012. Data from prospective studies and clinical trials suggest that lifestyle modifications and certain antihyperglycaemic medications, including thiazolidinediones (TZDs), glucagon-like peptide-1 (GLP-1) agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors and insulin, may preserve or enhance β-cell function. The implication of current data is that early initiation of lifestyle modifications and antihyperglycaemic agents that preserve β-cell function might reverse or delay progression to T2DM in those with prediabetes. Moreover, improved β-cell function may confer more durable glucose control and perhaps reduce/delay the incidence of diabetic complications. Long-term studies are needed to validate this hypothesis.

Physiologic and weight-focused treatment strategies for managing type 2 diabetes mellitus: the metformin, glucagon-like peptide-1 receptor agonist, and insulin (MGI) approach

The prevalence of type 2 diabetes mellitus (T2DM) is rising in association with an increase in obesity rates. Current treatment options for patients with T2DM include lifestyle modifications and numerous antidiabetic medications. Despite the availability of effective and well-tolerated treatments, many patients do not achieve recommended glycemic targets. Lack of efficacy is complicated by the wide range of available agents and little specificity in treatment guidelines, thus challenging clinicians to understand the relative benefits and risks of individual options for each patient. In this article, lifestyle intervention strategies and current antidiabetic agents are evaluated for their efficacy, safety, and weight-loss potential. Because of the heterogeneous and progressive nature of T2DM, physicians should advocate approaches that emphasize weight management, limit the risk of hypoglycemia and adverse events, and focus on the core pathophysiologic defects in patients with T2DM. A healthy, plant-based diet that is low in saturated fat and refined carbohydrates but high in whole grains, vegetables, legumes, and fruits, coupled with resistance and aerobic exercise regimens, are recommended for patients with T2DM. When necessary, drug intervention, described in this article as the MGI (metformin, glucagon-like peptide-1 receptor agonist, and insulin) approach, should begin with metformin and progress to the early addition of glucagon-like peptide-1 receptor agonists because of their weight loss potential and ability to target multiple pathophysiologic defects in patients with T2DM. For most patients, treatments that induce weight gain and hypoglycemia should be avoided. Long-acting insulin should be initiated if glycemic control is not achieved with metformin and glucagon-like peptide-1 receptor agonist combination therapy, focusing on long-acting insulin analogs that induce the least weight gain and have the lowest hypoglycemic risk. Ultimately, a patient-centered treatment approach that addresses the core pathologies of T2DM and obesity will not only increase overall efficacy and the likelihood that a patient adheres to treatment, but may also improve a patient's mental well-being and quality of life.

Interventions to preserve beta-cell function in the management and prevention of type 2 diabetes

The International Diabetes Federation estimates that there are currently 336 million people worldwide who have type 2 diabetes (T2DM), and the global prevalence of diabetes has more than doubled since 1980. The rapid rise in rates of T2DM echoes a similar rise in rates of obesity, which causes insulin resistance and places an increased insulin secretory demand on pancreatic β cells. While diabetes is diagnosed clinically by elevated plasma glucose levels, loss of β-cell function is progressive over time and β-cell dysfunction is far advanced by the time diabetes is diagnosed. Methods for preserving or restoring β-cell function are important for the prevention and treatment of T2DM. Interventions that reduce body fat or that change fat biology provide the best evidence for slowing or arresting the deterioration of β-cell function that causes T2DM. These interventions should form the basis of interventions to prevent and treat T2DM, particularly early in its course.

Curcumin extract for prevention of type 2 diabetes

OBJECTIVE

To assess the efficacy of curcumin in delaying development of type 2 diabetes mellitus (T2DM) in the prediabetic population.

RESEARCH DESIGN AND METHODS

This randomized, double-blinded, placebo- controlled trial included subjects (n = 240) with criteria of prediabetes. All subjects were randomly assigned to receive either curcumin or placebo capsules for 9 months. To assess the T2DM progression after curcumin treatments and to determine the number of subjects progressing to T2DM, changes in β-cell functions (homeostasis model assessment [HOMA]-β, C-peptide, and proinsulin/insulin), insulin resistance (HOMA-IR), anti-inflammatory cytokine (adiponectin), and other parameters were monitored at the baseline and at 3-, 6-, and 9-month visits during the course of intervention.

RESULTS

After 9 months of treatment, 16.4% of subjects in the placebo group were diagnosed with T2DM, whereas none were diagnosed with T2DM in the curcumin-treated group. In addition, the curcumin-treated group showed a better overall function of β-cells, with higher HOMA-β (61.58 vs. 48.72; P < 0.01) and lower C-peptide (1.7 vs. 2.17; P < 0.05). The curcumin-treated group showed a lower level of HOMA-IR (3.22 vs. 4.04; P < 0.001) and higher adiponectin (22.46 vs. 18.45; P < 0.05) when compared with the placebo group.

CONCLUSIONS

A 9-month curcumin intervention in a prediabetic population significantly lowered the number of prediabetic individuals who eventually developed T2DM. In addition, the curcumin treatment appeared to improve overall function of β-cells, with very minor adverse effects. Therefore, this study demonstrated that the curcumin intervention in a prediabetic population may be beneficial.

Effect of a long-term oral l-arginine supplementation on glucose metabolism: a randomized, double-blind, placebo-controlled trial

AIM

This study assessed the efficacy of long-term l-arginine (l-arg) therapy in preventing or delaying type 2 diabetes mellitus.

METHODS

A mono-centre, randomized, double-blind, parallel-group, placebo-controlled, phase III trial (l-arg trial) was conducted on 144 individuals affected by impaired glucose tolerance (IGT) and metabolic syndrome (MS). l-Arg/placebo was administered (6.4 g/day) on a background structured lifestyle intervention for 18 months plus a 12-month extended follow-up period after study drug termination. Fasting glucose levels and glucose tolerance after oral glucose tolerance test were evaluated throughout the study.

RESULTS

After 18 months, l-arg as compared with placebo did not reduce the cumulative incidence of diabetes [21.4 and 20.8%, respectively, hazard ratio (HR), 1.04; 95% confidence interval (CI), 0.58-1.86] while the cumulative probability to become normal glucose tolerant (NGT) increased (42.4 and 22.1%, respectively, HR, 2.60; 95% CI, 1.51-4.46, p < 0.001). The higher cumulative probability to become of NGT was maintained during the extended period in subjects previously treated with l-arg (HR, 3.21; 95% CI, 1.87-5.51; p < 0.001). At the end of the extended period, the cumulative incidence of diabetes in subjects previously treated with l-arg was reduced as compared with placebo (27.2 and 47.1%, respectively, HR, 0.42; 95% CI, 0.24-0.75, p < 0.05). During both periods, l-arg significantly improved insulin sensitivity and β-cell function.

CONCLUSION

Among persons with IGT and MS, the supplementation of l-arg for 18 months does not significantly reduce the incidence of diabetes but does significantly increase regression to NGT.

Cost and clinical implications of diabetes prevention in an Australian setting: a long-term modeling analysis

AIMS/HYPOTHESIS

Metformin and intensive lifestyle changes (ILC) reduced the incidence of type 2 diabetes (T2D) versus standard care (control) in overweight or obese subjects with impaired glucose tolerance (IGT) in the Diabetes Prevention Program (DPP) trial and Diabetes Prevention Program Outcomes Study (DPPOS). We projected lifetime clinical and economic outcomes based on the results from the DPP+DPPOS, from a 3rd-party payer perspective in Australia.

METHODS

A semi-Markov, 2nd-order Monte Carlo model was developed with four health states: "normal glucose regulation" (NGR); IGT; T2D and 'dead'. Outcomes were discounted at 5% annually. Univariate and probabilistic sensitivity analyses were performed. Incremental cost-effectiveness ratios (ICERs) were calculated.

RESULTS

Cumulative incidence (standard deviation) of T2D was 89.7% (0.2), 83.8% (0.2) and 73.4% (0.3%) for control, metformin and ILC respectively. Lifetime incremental direct costs were $1217 (4411) per subject for metformin versus control, with cost savings of $289 (4296) for ILC versus control. ILC therefore dominated control, with improvements in clinical outcomes and overall cost savings. Incremental costs per QALY-gained for metformin versus control were $10,142. Probability of cost-effectiveness at willingness-to-pay threshold of $50,000 was 78% and 100% for metformin or ILC respectively. Results were most sensitive to probabilities of developing T2D and costs of implementing the interventions.

CONCLUSIONS/INTERPRETATION

Substantial improvements in lifetime clinical outcomes could be expected in high risk subjects treated with metformin or ILC. Prevention of T2D in this group of subjects is good value for money, and may even lead to long term cost savings.

Beta-cell preservation…Is weight loss the answer?

Obesity is associated with an increased risk of type 2 diabetes (T2D). Pancreatic beta-cell failure is an early event in the development of glucose dysregulation and diabetes. Interventions to halt beta-cell failure in T2D include diet modification, exercise, and use of pharmacologic agents. There is evidence that abdominal obesity may contribute to diabetes through insulin resistance and beta-cell impairment. Pivotal long-term studies into the prevention of T2D have shown the importance of weight loss beside diet, lifestyle, and medication. The Finnish Diabetes Prevention Program (DPP) showed that weight loss gradually reduces the risk of diabetes, and that even modest weight loss can significantly reduce the incidence of T2D. Similarly, in the US DPP, weight loss as part of intensive lifestyle modification was the major factor in reducing the incidence of T2D in high-risk subjects, being more effective than drug intervention. While understanding the relationship between obesity and diabetes is complex, we know that weight loss has positive effects on adipose tissue. It causes an increase in the beneficial fat cell hormone adiponectin, and a decrease in adipose tissue inflammation. Also, it is associated with reduced insulin resistance and a consequential reduction in glucolipotoxicity, which can improve beta-cell function. In summary, weight loss improves glycemic control and thereby mitigates diabetes symptoms and complications, possibly through the preservation of beta-cell function. Therefore, efforts to prevent diabetes and preserve beta-cell function in patients with T2D should more consequently emphasize and target weight loss.

The renin-angiotensin system in the pathophysiology of type 2 diabetes

Increased activation of the renin-angiotensin system (RAS) has been related to cardiovascular disease and type 2 diabetes mellitus. Most randomized clinical trials have demonstrated that RAS blockade reduces the incidence of type 2 diabetes, which has been explained by improved insulin secretion and insulin sensitivity. In this review, an overview of the mechanisms that may underlie the association between the RAS and type 2 diabetes will be provided, with focus on skeletal muscle and adipose tissue function. This will include discussion of several human studies performed in our laboratory to investigate the metabolic and hemodynamic effects of the RAS, combining in vivo measurements of whole-body and tissue metabolism with molecular and immunohistochemical approaches. Available data suggest that the detrimental effects of the RAS on insulin secretion are mediated by a reduction in pancreatic blood flow and induction of islet fibrosis, oxidative stress as well as inflammation, whereas both impaired skeletal muscle function and adipose tissue dysfunction may underlie RAS-induced insulin resistance. Thus, although future studies in humans are warranted, current evidence supports that targeting the RAS in intervention studies may improve metabolic and cardiovascular function in conditions of insulin resistance like obesity and type 2 diabetes.

The effects of rosiglitazone on inflammatory biomarkers and adipokines in diabetic, hypertensive patients

OBJECTIVE

To compare the effects of a 12-week treatment course of a rosiglitazone-based versus a metformin- or glyburide-based strategy on inflammatory biomarkers and adipokine levels in hypertensive, type 2 diabetes patients.

METHODS

One hundred three treatment-naive patients or patients on monotherapy with either metformin or glyburide, and a hemoglobin A1C (A1C) ≥7.5%, were randomly assigned to either rosiglitazone add-on (4 mg/day ± titration to 8 mg/day) or a combination of metformin (250 mg twice per day [BID] titrated to 500 BID if A1C ≥7.5% and ≤8.0%; 500 mg BID titrated to 1 g BID if A1C >8.0%) and glyburide (2.5 mg BID titrated to 5 mg BID if A1C ≥7.5% and ≤8.0%; 5 mg BID titrated to 10 mg BID if A1C >8.0%).

RESULTS

Rosiglitazone add-on produced significantly greater reductions in high-sensitivity C-reactive protein (2.1 mg/L to 0.9 mg/L) and increases in adiponectin (8.7 mg/mL to 14.8 mg/mL) levels compared with metformin/glyburide (both P<0.005). At close-out, all patients had improved fasting plasma glucose and A1C levels (8.5% to 7.4% and 8.8% to 7.1% for rosiglitazone add-on and metformin-glyburide, respectively [P<0.001 for both arms]) relative to the corresponding baseline values.

CONCLUSIONS

The present study demonstrated that in hypertensive, diabetic subjects, a rosiglitazone-based treatment strategy results in favourable changes in inflammatory biomarkers compared with metformin/glyburide.

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.

Elevated intact proinsulin levels are indicative of Beta-cell dysfunction, insulin resistance, and cardiovascular risk: impact of the antidiabetic agent pioglitazone

BACKGROUND

Insulin resistance (IR) and deterioration of beta-cell secretion are main features in the development of type 2 diabetes, which is reflected in increasing serum intact proinsulin levels in later disease stage. Introduction of stable assays that are able to distinguish between intact proinsulin and its specific and unspecific cleavage products has resulted in the finding that serum intact proinsulin values can serve as a direct marker for beta-cell dysfunction, are a highly specific indicator of IR, and can predict cardiovascular risk.

METHOD

Determination of fasting intact proinsulin may be used to monitor and optimize antidiabetic therapeutic approaches. Our study group has been involved in a variety of clinical studies investigating drug effects on beta-cell secretory capacity, IR, and intact proinsulin levels. One focus was on the impact of insulin-sensitizing therapy with pioglitazone on the pancreatic beta-cell load.

RESULTS

Treatment with pioglitazone resulted in significant decreases in elevated proinsulin levels in type 2 diabetes patients. This effect was independent from glycemic control.

CONCLUSIONS

Measurement of fasting intact proinsulin values allows a staging of beta-cell dysfunction and evaluation of IR, thus providing an interesting diagnostic tool for both selection of appropriate therapy and monitoring of treatment success.

Long-term effect of rosiglitazone and/or ramipril on the incidence of diabetes

AIMS/HYPOTHESIS

The Diabetes Reduction Assessment with Ramipril and Rosiglitazone Medication (DREAM) trial reported that 3 years of therapy with rosiglitazone reduced the primary outcome of diabetes or death by 60%. Here we investigated whether an effect on diabetes prevention persists more than 1.5 years after therapy has been discontinued.

METHODS

The DREAM On passive follow-up study was conducted at 49 of the 191 DREAM sites. Consenting participants were invited to have a repeat OGTT 1-2 years after active therapy ended. A diagnosis of diabetes at that time was based on either a fasting or 2 h plasma glucose level of ≥7.0 mmol/l or ≥11.1 mmol/l, respectively, or a confirmed diagnosis by a non-study physician. Regression to normoglycaemia was defined as a fasting and 2 h plasma glucose level of <6.1 mmol/l and <7.8 mmol/l, respectively.

RESULTS

After a median of 1.6 years after the end of the trial and 4.3 years after randomisation, rosiglitazone participants had a 39% lower incidence of the primary outcome (hazard ratio [HR] 0.61, 95% CI 0.53-0.70; p < 0.0001) and 17% more regression to normoglycaemia (95% CI 1.01-1.34; p = 0.034). When the analysis was restricted to the passive follow-up period, a similar incidence of both the primary outcome and regression was observed in people from both treatment groups (HR 1.00, 95% CI 0.81-1.24 and HR 1.14, 95% CI 0.97-1.32, respectively). Similar effects were noted when new diabetes was analysed separately from death. Ramipril did not have any significant long-term effect.

CONCLUSIONS/INTERPRETATION

Time-limited exposure to rosiglitazone reduces the longer term incidence of diabetes by delaying but not reversing the underlying disease process.

Hypertension 2010: what was new for the cardiologist?

IMPORTANCE OF THE FIELD

Despite extensive clinical research, still there is some uncertainty regarding management of hypertension, in particular initial and goal blood pressure levels and selection of optimal pharmacotherapy, as well as concomitant medications, to reduce other risk factors.

AREAS COVERED IN THIS REVIEW

An overview of recent findings from major clinical trials in hypertension (until July 2010), along with a reappraisal of the European Society of Hypertension 2009 guidelines.

WHAT THE READER WILL GAIN

Practical overview of the management of hypertension, including threshold and goal blood pressure in specific situations, choice of antihypertensive medications and indications for treatment of concomitant risk factors.

TAKE HOME MESSAGE

Primary benefits of antihypertensive therapy are mediated by blood pressure reduction and the majority of patients will require at least two drugs, with the preference of fixed-dose combinations for effective blood pressure control.

Weight considerations in pharmacotherapy for type 2 diabetes

Obesity has been increasing in prevalence worldwide and the majority of patients with type 2 diabetes are either overweight or obese. Diabetes management in this population has been difficult since a number of antidiabetes agents are associated with weight gain. The effects of various antidiabetes agents and antiobesity agents on glycemic control and body weight will be reviewed. Briefly, sulfonylureas, thiazolidinediones, and insulin are associated with weight gain, whereas metformin and amylin analogs are weight neutral or associated with modest weight loss. Dipeptidyl-peptidase-4 inhibitors are weight neutral, whereas glucagon-like peptide-1 analogs are associated with weight loss. The effect of orlistat and sibutramine in type 2 diabetes is also evaluated. The treatment of diabetes should not only focus on glycemic control as its sole intention, but it should factor in the effect of these various agents on weight, as well, since obesity aggravates insulin resistance, beta cell failure, and cardiovascular risk.

The role of peroxisome proliferator-activated receptor γ in pancreatic β cell function and survival: therapeutic implications for the treatment of type 2 diabetes mellitus

The pathogenesis of type 2 diabetes mellitus involves both peripheral insulin resistance and dysfunctional insulin secretion from the pancreatic β cell. Currently, there is intense research focus on delineating the etiologies of pancreatic β cell dysfunction in type 2 diabetes. However, there remains an unmet clinical need to establish therapeutic guidelines and strategies that emphasize the preservation of pancreatic β cell function in at-risk and affected individuals. Thiazolidinediones are orally active agents approved for use in type 2 diabetes and act as agonists of the nuclear hormone receptor PPAR-γ. These drugs improve insulin sensitivity, but there is also a growing appreciation of PPAR-γ actions within the β cell. PPAR-γ has been shown to regulate directly key β cell genes involved in glucose sensing, insulin secretion and insulin gene transcription. Further, pharmacologic PPAR-γ activation has been shown to protect against glucose-, lipid-, cytokine- and islet amyloid polypeptide (IAPP)-induced activation of numerous stress pathways. This article will review the mechanisms by which PPAR-γ activation acts to maintain β cell function and survival in type 2 diabetes mellitus and highlight some of the current controversies in this field.

Prediabetes as a therapeutic target

BACKGROUND

The term "prediabetes" is used to describe a condition that involves impaired glucose tolerance (IGT) or impaired fasting glucose (IFG). IGT is defined by a 2-h oral glucose tolerance test plasma glucose concentration >140 mg/dL (7.8 mmol/L) but <200 mg/dL (11.1 mmol/L), and IFG is defined by a fasting plasma glucose concentration ≥100 mg/dL (5.6 mmol/L), but <126 mg/dL (7.0 mmol/L). Studies have shown that people with prediabetes tend to develop type 2 diabetes within 10 years and are at increased risk for cardiovascular disease and death even before the development of diabetes.

CONTENT

In this minireview we discusses the epidemiology, pathophysiology, and clinical implications of prediabetes. The rationale for therapeutic intervention in people with prediabetes, the goals of intervention, and the specific tools for intervention are presented. Emphasis is placed on data from randomized controlled clinical trials, whenever such data are available.

SUMMARY

Approximately 57 million Americans have prediabetes and are consequently at risk for cardiometabolic complications. Lifestyle modifications (dietary restriction and exercise) and certain medications can prevent the development of diabetes in persons with prediabetes. Lifestyle intervention also has been demonstrated to decrease cardiovascular disease risk markers, although data on clinical events are lacking.

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.