Mechanism of Glucagon-Like Peptide 1 Improvements in Type 2 Diabetes Mellitus and Obesity

Dietary impact on fasting and stimulated GLP-1 secretion in different metabolic conditions - a narrative review

Glucagon-like peptide 1 (GLP-1), a gastrointestinal peptide and central mediator of glucose metabolism, is secreted by L cells in the intestine in response to food intake. Postprandial secretion of GLP-1 is triggered by nutrient-sensing via transporters and G-protein-coupled receptors (GPCRs). GLP-1 secretion may be lower in adults with obesity/overweight (OW) or type 2 diabetes mellitus (T2DM) than in those with normal glucose tolerance (NGT), but these findings are inconsistent. Because of the actions of GLP-1 on stimulating insulin secretion and promoting weight loss, GLP-1 and its analogs are used in pharmacologic preparations for the treatment of T2DM. However, physiologically stimulated GLP-1 secretion through the diet might be a preventive or synergistic method for improving glucose metabolism in individuals who are OW, or have impaired glucose tolerance (IGT) or T2DM. This narrative review focuses on fasting and postprandial GLP-1 secretion in individuals with different metabolic conditions and degrees of glucose intolerance. Further, the influence of relevant diet-related factors (e.g., specific diets, meal composition, and size, phytochemical content, and gut microbiome) that could affect fasting and postprandial GLP-1 secretion are discussed. Some studies showed diminished glucose- or meal-stimulated GLP-1 response in participants with T2DM, IGT, or OW compared with those with NGT, whereas other studies have reported an elevated or unchanged GLP-1 response in T2DM or IGT. Meal composition, especially the relationship between macronutrients and interventions targeting the microbiome can impact postprandial GLP-1 secretion, although it is not clear which macronutrients are strong stimulants of GLP-1. Moreover, glucose tolerance, antidiabetic treatment, grade of overweight/obesity, and sex were important factors influencing GLP-1 secretion. The results presented in this review highlight the potential of nutritional and physiologic stimulation of GLP-1 secretion. Further research on fasting and postprandial GLP-1 concentrations and the resulting metabolic consequences under different metabolic conditions is needed.

The Impact of Glucagon-like Peptide 1 Receptor Agonists on Obstructive Sleep Apnoea: A Scoping Review

BACKGROUND

Obstructive sleep apnoea (OSA) and associated hypopnoea syndromes are chronic conditions of sleep-disordered breathing with significant sequelae if poorly managed, including hypertension, cardiovascular disease, metabolic syndrome and increased mortality. Glucagon-like peptide 1 receptor agonists (GLP-1RA) have recently garnered significant interest as a potential therapeutic, attributed to their durable effects in weight loss and glycaemic control in metabolic syndromes, such as obesity and type 2 diabetes mellitus. This has led to significant investment into companies that produce these medications and divestment from traditional gold standard methods of OSA management such as continuous positive airway pressure machines. Despite these sentiments, the impacts of these medications on OSA outcomes are poorly characterised, with no high-quality evidence at this stage to support this hypothesis. This scoping review therefore aims to address the research question of whether GLP-1RAs lead to a direct improvement in OSA and associated hypopnoea syndromes.

METHODS

A scoping review was performed following a computer-assisted search of Medline, Embase and Cochrane Central databases. Papers that evaluated the use of GLP-1RA medications related to sleep-disordered breathing, OSA or other sleep-related apnoeic or hypopnoeic syndromes were included.

RESULTS

Literature search and evaluation identified 9 articles that were eligible for inclusion. Of these, 1 was a study protocol, 1 was a case report, 1 was an abstract of a randomised controlled trial (RCT), 1 was a non-randomised clinical trial and the remaining 5 were randomised clinical trials of variable rigour. All studies evaluated the outcomes of GLP-1RAs in patients with diagnosed OSA or symptoms suggestive of this condition.

CONCLUSION

This scoping review identified early evidence to suggest that GLP-1RAs may improve OSA as defined by reduction in apnoea-hypopnoea index (AHI). This evidence is however conflicting due to contradicting results demonstrated from other studies. Overall, these medications were tolerated well, with minor gastrointestinal side-effects reported in some cases. Of all included studies, the quality of evidence was low, with short lengths of follow-up to identify durable effects of these medications on OSA outcomes and identify adverse events. More rigorous, RCTs with sufficient length of follow-up are required before consideration of formalising these medications into OSA treatment guidelines, frameworks and policies are warranted.

Obesity Management in Adults: A Review

Importance

Obesity affects approximately 42% of US adults and is associated with increased rates of type 2 diabetes, hypertension, cardiovascular disease, sleep disorders, osteoarthritis, and premature death.

Observations

A body mass index (BMI) of 25 or greater is commonly used to define overweight, and a BMI of 30 or greater to define obesity, with lower thresholds for Asian populations (BMI ≥25-27.5), although use of BMI alone is not recommended to determine individual risk. Individuals with obesity have higher rates of incident cardiovascular disease. In men with a BMI of 30 to 39, cardiovascular event rates are 20.21 per 1000 person-years compared with 13.72 per 1000 person-years in men with a normal BMI. In women with a BMI of 30 to 39.9, cardiovascular event rates are 9.97 per 1000 person-years compared with 6.37 per 1000 person-years in women with a normal BMI. Among people with obesity, 5% to 10% weight loss improves systolic blood pressure by about 3 mm Hg for those with hypertension, and may decrease hemoglobin A1c by 0.6% to 1% for those with type 2 diabetes. Evidence-based obesity treatment includes interventions addressing 5 major categories: behavioral interventions, nutrition, physical activity, pharmacotherapy, and metabolic/bariatric procedures. Comprehensive obesity care plans combine appropriate interventions for individual patients. Multicomponent behavioral interventions, ideally consisting of at least 14 sessions in 6 months to promote lifestyle changes, including components such as weight self-monitoring, dietary and physical activity counseling, and problem solving, often produce 5% to 10% weight loss, although weight regain occurs in 25% or more of participants at 2-year follow-up. Effective nutritional approaches focus on reducing total caloric intake and dietary strategies based on patient preferences. Physical activity without calorie reduction typically causes less weight loss (2-3 kg) but is important for weight-loss maintenance. Commonly prescribed medications such as antidepressants (eg, mirtazapine, amitriptyline) and antihyperglycemics such as glyburide or insulin cause weight gain, and clinicians should review and consider alternatives. Antiobesity medications are recommended for nonpregnant patients with obesity or overweight and weight-related comorbidities in conjunction with lifestyle modifications. Six medications are currently approved by the US Food and Drug Administration for long-term use: glucagon-like peptide receptor 1 (GLP-1) agonists (semaglutide and liraglutide only), tirzepatide (a glucose-dependent insulinotropic polypeptide/GLP-1 agonist), phentermine-topiramate, naltrexone-bupropion, and orlistat. Of these, tirzepatide has the greatest effect, with mean weight loss of 21% at 72 weeks. Endoscopic procedures (ie, intragastric balloon and endoscopic sleeve gastroplasty) can attain 10% to 13% weight loss at 6 months. Weight loss from metabolic and bariatric surgeries (ie, laparoscopic sleeve gastrectomy and Roux-en-Y gastric bypass) ranges from 25% to 30% at 12 months. Maintaining long-term weight loss is difficult, and clinical guidelines support the use of long-term antiobesity medications when weight maintenance is inadequate with lifestyle interventions alone.

Conclusion and Relevance

Obesity affects approximately 42% of adults in the US. Behavioral interventions can attain approximately 5% to 10% weight loss, GLP-1 agonists and glucose-dependent insulinotropic polypeptide/GLP-1 receptor agonists can attain approximately 8% to 21% weight loss, and bariatric surgery can attain approximately 25% to 30% weight loss. Comprehensive, evidence-based obesity treatment combines behavioral interventions, nutrition, physical activity, pharmacotherapy, and metabolic/bariatric procedures as appropriate for individual patients.

Real-world evaluation of weekly subcutaneous treatment with semaglutide in a cohort of Italian diabetic patients

PURPOSE

Registered trials and real-world evidence (RWE) studies provided evidence on the efficacy of once-weekly (OW) semaglutide on hyperglycaemia and cardiovascular risk factors as add-on or de-novo treatment in type 2 diabetes (T2D).

METHODS

In a retrospective analysis of electronic data files from 258 T2D patients, this RWE study aimed to explore the impact of OW semaglutide on biochemical and anthropometric outcomes after 6 and 12 months in patients receiving at least one prescription of OW semaglutide between September 2019 and May 2021.

RESULTS

During the study period, 154 and 56 consecutive patients completed the 6 and 12 months of OW semaglutide treatment. HbA1c levels decreased by -1.02±0.1% after 6 months and -1.1±0.1% after 12 months of OW semaglutide (p<0.0001 for both). At these time-points, HbA1c values were <7% in 61% and 57% of cases. HbA1c reduction was greater in patients with higher baseline HbA1c levels and it occurred irrespective of gender, age, insulin therapy and complications. The residual number of cases with HbA1c ≥9% by the study end was low (5.3% vs 18.9% at baseline). Weight loss occurred in 73.5% and 78.1% of cases and, compared to baseline, it was ≥5% in 21.2- 25.4% and ≥10% in 6.8-18.2% after 6 and 12 months, respectively. Significant predictors of HbA1c reduction after 6 months of OW semaglutide treatment were baseline HbA1c (p<0.0001), bodyweight reduction (p<0.0001) and disease duration (p<0.001), while baseline HbA1c was the only predictor of HbA1c response after 12 months (p<0.0001). Reported adverse events were consistent with the known safety profile of semaglutide.

CONCLUSIONS

Real-world evaluation of weekly subcutaneous treatment with semaglutide in a cohort of Italian diabetic patients.

Glucagon-Like Peptide 1 Receptor Agonist Improves Renal Tubular Damage in Mice with Diabetic Kidney Disease

PURPOSE

This study aims to investigate the renal protective effect of glucagon-like peptide 1 receptor agonist (GLP-1RA) on improving renal tubular damage in diabetic kidney disease (DKD) and to explore the potential mechanism of GLP-1RA on renal tubular protection.

METHODS

Long-acting GLP-1RA was used to treat DKD mice for 12 weeks. The label-free quantitative proteomic analysis of renal proteins was conducted to explore the differentially expressed proteins (DEPs) in the renal tissues of the control, DKD and GLP-1RA groups. The DEPs and markers of renal tubular injury were verified by qPCR in vivo and in vitro. The expression of glucagon-likepeptide-1 receptor (GLP-1R) in renal tubules was determined by immunofluorescence staining.

RESULTS

GLP-1RA treatment significantly improved the tubular damages in kidney tissues of DKD mice and mTEC cells stimulated by high glucose (HG). Proteomics analysis revealed that 30 proteins in kidney tissue were differentially expressed among three groups. Seminal vesicle secretory protein 6 (SVS6) was the most differentially expressed protein in kidney tissues among three groups of mice. The expression changes of Svs6 mRNA in vitro and in vivo detected by qPCR were consistent with the results of proteomic analysis. Furthermore, reduction of Svs6 expression by SVS6 siRNA could attenuate HG-stimulated tubular injury in mTEC cells. Immunofluorescence staining also found that GLP-1R was widely expressed in renal tubules in vitro and in vivo.

CONCLUSION

GLP-1RA significantly improved renal tubular damage in DKD mice. SVS6 may be a potential therapeutic target for GLP-1RA in the treatment of DKD.

Clinical Impact of GLP-1 receptor agonists in veterans receiving basal-bolus insulin

BACKGROUND

In 2017, an estimated 7.4 million Americans used insulin to treat diabetes. Insulin is proven to lower A1c but can result in hypoglycemia and weight gain. Combining insulin with a glucagon-like peptide-1 receptor agonist (GLP-1-RA) may provide additional blood glucose control while limiting undesirable effects including weight gain.

OBJECTIVE

To characterize the clinical impact of adding a GLP-1-RA to a basal-bolus insulin regimen in patients with type 2 diabetes.

METHODS

This retrospective observational study used national Veteran's Health Administration data to identify patients with an existing basal-bolus insulin regimen who initiated a GLP-1-RA between January 1, 2005 and December 31, 2017. A1c, insulin total daily dose (TDD), and weight were collected at GLP-1-RA initiation (baseline), 3-, 6-, and 12-month time points and then analyzed using an intent-to-treat approach with the last observation carried forward. Decreases in A1c ≥ 0.5% and weight ≥2 kg were deemed clinically significant.

RESULTS

Among 7651 patients initiating GLP-1-RA therapy, mean A1c had a clinically significant decline at 3, 6, and 12 months by -0.5%, -0.7%, and -0.7%, respectively, from a mean baseline of 9%. Patients with lower baseline A1c levels did not have clinically significant changes in A1c, whereas patients with baseline A1c ≥9% had more clinically significant declines. Insulin TDD decreased by -32, -38, and -42 units/day at 3, 6, and 12 months, respectively, where the mean decrease in insulin TDD at 12 months was 79 units/day among patients who discontinued bolus insulin (52.3%) compared with a mean decrease of 2 units/day among those who continued bolus insulin. Mean weight reductions at 3, 6, and 12 months were -1.2, -2.3, and -2.9 kg, respectively, from a mean baseline of 120.6 kg.

CONCLUSION

Combining a GLP-1-RA with basal-bolus insulin had a clinically significant improvement on blood glucose control, lowered insulin TDD, and reduced weight. These outcomes were achieved within 3 to 6 months following GLP-1-RA initiation and were maintained through 1 year.

Berberine activates the β-catenin/TCF4 signaling pathway by down-regulating miR-106b to promote GLP-1 production by intestinal L cells

Berberine facilitates the production of glucagon-like peptide-1 (GLP-1) by intestinal L cells. Here, we aimed to reveal the mechanism of berberine facilitating the production of GLP-1 by intestinal L cells. In this study, we confirmed that the 100 mg/kg berberine daily through diet decreased the miR-106b expression and elevated the expressions of β-catenin and T-cell factor 4 (TCF4) in colon tissues of high-fat diet mice; berberine decreased the concentrations of triglycerides, total cholesterol and the ratio of low-density lipoprotein cholesterol and high-density lipoprotein cholesterol in mouse serum samples; berberine decreased the blood glucose in the mouse tail vein blood and promoted GLP-1 production by intestinal L cells in mouse serum samples and elevated the GLP-1 expression in mouse colon tissues. Meanwhile, the mechanism analysis demonstrated that a dose of 100 μM berberine down-regulated the miR-106b expression by elevating the methylation levels of miR-106b in STC-1 cells and miR-106b bound to TCF4 in 293T cells. Moreover, the 100 mg/kg berberine daily through diet activated the β-catenin/TCF4 signaling pathway by decreasing miR-106b, thereby facilitating GLP-1 production in intestinal L cells through the in vivo assays. Conclusively, our experimental data illustrated that berberine decreased miR-106b expression by increasing its methylation levels and then activated the β-catenin/TCF4 signaling pathway, thereby facilitating GLP-1 production by intestinal L cells.

Effect of dulaglutide 3.0 and 4.5 mg on weight in patients with type 2 diabetes: Exploratory analyses of AWARD-11

AIM

To evaluate the impact of dulaglutide 3.0 and 4.5 mg versus 1.5 mg on body weight in patients with type 2 diabetes (T2D) based on exploratory analyses of the AWARD-11 trial.

MATERIALS AND METHODS

Patients were randomized to once-weekly dulaglutide 1.5 (n = 612), 3.0 (n = 616) or 4.5 mg (n = 614) for 52 weeks. The primary objective was superiority of dulaglutide 3.0 and/or 4.5 mg over 1.5 mg in HbA1c reduction at 36 weeks. Secondary and exploratory assessments included weight reduction in the overall trial population and baseline body mass index (BMI) and HbA1c subgroups.

RESULTS

At baseline, patients had a mean age of 57.1 years, HbA1c 8.6% (70 mmol/mol), weight 95.7 kg and BMI 34.2 kg/m² . At 36 weeks, dulaglutide 3.0 and 4.5 mg were superior to 1.5 mg for weight change from baseline (1.5 mg, -3.1 kg; 3.0 mg, -4.0 kg [P = .001]; 4.5 mg, -4.7 kg [P < .001]). Higher dulaglutide doses were associated with numerically greater weight reduction compared with 1.5 mg in each baseline BMI and HbA1c subgroup. Absolute weight reduction increased with increasing BMI category, but percentage weight loss was similar between subgroups. Weight reductions with dulaglutide were greater in patients with lower versus higher baseline HbA1c.

CONCLUSIONS

In patients with T2D, inadequately controlled by metformin, incremental weight loss was observed with dulaglutide 1.5, 3.0 and 4.5 mg doses regardless of baseline BMI or HbA1c. Although absolute weight loss was numerically greater in patients with higher baseline BMI, percentage of weight loss was similar between BMI subgroups.

Future perspectives in diabesity treatment: Semaglutide, a glucagon-like peptide 1 receptor agonist (Review)

Given their endemic prevalence in the past decades, obesity and type 2 diabetes mellitus (T2DM) have become a major sanitary burden with an important economic impact. Novel treatment options have been designed with the aim of reducing the numerous complications associated with these metabolic disorders, as well as reducing morbidity and mortality and improving the quality of life of those who suffer from these disorders. Glucagon-like peptide 1 receptor agonists (GLP-1 RAs) are among the most modern therapeutics that target ‘diabesity’, a term used to describe the pathophysiological link between obesity and T2DM. Their glucose-lowering effects are mainly attributed to glucose-dependent insulin secretion, glucagon inhibition and decreased gastric emptying. Given the effects on the central nervous system, GLP-1 RA usage may lead to body weight reduction. GLP-1 RAs are classified based on their pharmacokinetic properties as short- and long-acting agents, with both types being administered by subcutaneous injection. The latest agent from this drug class approved for use in T2DM is semaglutide, a long-acting compound that is the only GLP-1 RA available as an oral pill. The present narrative review highlights the most recently published data on the effects and safety of semaglutide in diabetic obesity, also emphasizing its cardiovascular benefits and potential side effects. In addition, an overview of the role of semaglutide in the treatment of non-diabetic obesity is provided.

A 2021 Update on the Use of Liraglutide in the Modern Treatment of 'Diabesity': A Narrative Review

Obesity and type 2 diabetes mellitus have become a significant public health problem in the past decades. Their prevalence is increasing worldwide each year, greatly impacting the economic and personal aspects, mainly because they frequently coexist, where the term “diabesity” may be used. The drug class of glucagon-like peptide 1 receptor agonists (GLP-1 RAs) is one of the most modern therapy options in managing these metabolic disorders. This review focuses on the effects of liraglutide, a long-acting GLP-1 RA, in diabesity and non-diabetic excess weight. This drug class improves glycemic control by enhancing insulin secretion from the beta-pancreatic cells and inhibiting glucagon release. Furthermore, other effects include slowing gastric emptying, increasing postprandial satiety, and reducing the appetite and food consumption by influencing the central nervous system, with weight reduction effects. It also reduces cardiovascular events and has positive effects on blood pressure and lipid profile. A lower-dose liraglutide (1.2 or 1.8 mg/day) is used in patients with diabetes, while the higher dose (3.0 mg/day) is approved as an anti-obesity drug. In this review, we have summarized the role of liraglutide in clinical practice, highlighting its safety and efficacy as a glucose-lowering agent and a weight-reduction drug in patients with and without diabetes.

Efficacy and Safety of Dulaglutide in Older Patients: A post hoc Analysis of the REWIND trial

CONTEXT

Dulaglutide reduced major adverse cardiovascular events (MACE) in the Researching Cardiovascular Events with a Weekly INcretin in Diabetes (REWIND) trial. Its efficacy and safety in older vs younger patients have not been explicitly analyzed.

OBJECTIVE

This work aimed to assess efficacy and safety of dulaglutide vs placebo in REWIND by age subgroups (≥ 65 and < 65 years).

METHODS

A post hoc subgroup analysis of REWIND was conducted at 371 sites in 24 countries. Participants included type 2 diabetes patients aged 50 years or older with established cardiovascular (CV) disease or multiple CV risk factors, and a wide range of glycemic control. Patients were randomly assigned (1:1) to dulaglutide 1.5 mg or placebo as an add-on to country-specific standard of care. Main outcomes measures included MACE (first occurrence of the composite of nonfatal myocardial infarction, nonfatal stroke, or death from CV or unknown causes).

RESULTS

There were 5256 randomly assigned patients who were 65 years or older (mean = 71.0), and 4645 were younger than 65 years (mean = 60.7). Baseline characteristics were similar in randomized treatment groups. Dulaglutide treatment showed a similar reduction in the incidence (11% vs 13%) of MACE in older vs younger patients. The rate of permanent study drug discontinuation, incidence of all-cause mortality, hospitalizations for heart failure, severe hypoglycemia, severe renal or urinary events, and serious gastrointestinal events were similar between randomized treatment groups within each age subgroup. The incidence rate of serious cardiac conduction disorders was numerically higher in the dulaglutide group compared to placebo within each age subgroup but the difference was not statistically significant.

CONCLUSION

Dulaglutide had similar efficacy and safety in REWIND in patients65 years and older and those younger than 65 years.

Incretin Hormones in Obesity and Related Cardiometabolic Disorders: The Clinical Perspective

The prevalence of obesity continues to grow rapidly worldwide, posing many public health challenges of the 21st century. Obese subjects are at major risk for serious diet-related noncommunicable diseases, including type 2 diabetes mellitus, cardiovascular disease, and non-alcoholic fatty liver disease. Understanding the mechanisms underlying obesity pathogenesis is needed for the development of effective treatment strategies. Dysregulation of incretin secretion and actions has been observed in obesity and related metabolic disorders; therefore, incretin-based therapies have been developed to provide new therapeutic options. Incretin mimetics present glucose-lowering properties, together with a reduction of appetite and food intake, resulting in weight loss. In this review, we describe the physiology of two known incretins—glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), and their role in obesity and related cardiometabolic disorders. We also focus on the available and incoming incretin-based medications that can be used in the treatment of the above-mentioned conditions.

Prominent and emerging anti-diabetic molecular targets

Diabetes is on the rise across the globe affecting more than 463 million people and crucially increasing morbidities of diabetes-associated diseases. Urgent and immense actions are needed to improve diabetes prevention and treatment. Regarding the correlation of diabetes with many associated diseases, inhibition of the disease progression is more crucial than controlling symptoms. Currently, anti-diabetic drugs are accompanied by undesirable side-effects and target confined types of biomolecules. Thus, extensive research is demanding to identify novel disease mechanisms and molecular targets as probable candidates for effective treatment of diabetes. This review discusses the conventional molecule targets that have been applied for their therapeutic rationale in treatment of diabetes. Further, the emerging and prospective molecular targets for the future focus of library screenings are presented.

The Coming Age of Flavonoids in the Treatment of Diabetic Complications

Diabetes mellitus (DM), and its micro and macrovascular complications, is one of the biggest challenges for world public health. Despite overall improvement in prevention, diagnosis and treatment, its incidence is expected to continue increasing over the next years. Nowadays, finding therapies to prevent or retard the progression of diabetic complications remains an unmet need due to the complexity of mechanisms involved, which include inflammation, oxidative stress and angiogenesis, among others. Flavonoids are natural antioxidant compounds that have been shown to possess anti-diabetic properties. Moreover, increasing scientific evidence has demonstrated their potential anti-inflammatory and anti-oxidant effects. Consequently, the use of these compounds as anti-diabetic drugs has generated growing interest, as is reflected in the numerous in vitro and in vivo studies related to this field. Therefore, the aim of this review is to assess the recent pre-clinical and clinical research about the potential effect of flavonoids in the amelioration of diabetic complications. In brief, we provide updated information concerning the discrepancy between the numerous experimental studies supporting the efficacy of flavonoids on diabetic complications and the lack of appropriate and well-designed clinical trials. Due to the well-described beneficial effects on different mechanisms involved in diabetic complications, the excellent tolerability and low cost, future randomized controlled studies with compounds that have adequate bioavailability should be evaluated as add-on therapy on well-established anti-diabetic drugs.

S100 proteins in obesity: liaisons dangereuses

Obesity is an endemic pathophysiological condition and a comorbidity associated with hypercholesterolemia, hypertension, cardiovascular disease, type 2 diabetes mellitus, and cancer. The adipose tissue of obese subjects shows hypertrophic adipocytes, adipocyte hyperplasia, and chronic low-grade inflammation. S100 proteins are Ca2+-binding proteins exclusively expressed in vertebrates in a cell-specific manner. They have been implicated in the regulation of a variety of functions acting as intracellular Ca2+ sensors transducing the Ca2+ signal and extracellular factors affecting cellular activity via ligation of a battery of membrane receptors. Certain S100 proteins, namely S100A4, the S100A8/S100A9 heterodimer and S100B, have been implicated in the pathophysiology of obesity-promoting macrophage-based inflammation via toll-like receptor 4 and/or receptor for advanced glycation end-products ligation. Also, serum levels of S100A4, S100A8/S100A9, S100A12, and S100B correlate with insulin resistance/type 2 diabetes, metabolic risk score, and fat cell size. Yet, secreted S100B appears to exert neurotrophic effects on sympathetic fibers in brown adipose tissue contributing to the larger sympathetic innervation of this latter relative to white adipose tissue. In the present review we first briefly introduce S100 proteins and then critically examine their role(s) in adipose tissue and obesity.

Differently Expressed Genes (DEGs) Relevant to Type 2 Diabetes Mellitus Identification and Pathway Analysis via Integrated Bioinformatics Analysis

BACKGROUND The aim of this study was to evaluate the differently expressed genes (DEGs) relevant to type 2 diabetes mellitus (T2DM) and pathway by performing integrated bioinformatics analysis. MATERIAL AND METHODS The gene expression datasets GSE7014 and GSE29221 were downloaded in GEO database, and DEGs from type 2 diabetes mellitus and normal skeletal muscle tissues were identified. Biological function analysis of the DEGs was enriched by GO and KEEG pathway. A PPI network for the identified DEGs was built using the STRING database. RESULTS Thirty top DEGs were identified from 2 datasets: GSE7014 and GSE29221. Of the 30 top DEGs, 20 were up-regulated and 10 were down-regulated. The 20 up-regulated genes were enriched in regulation of mRNA, protein biding, and phospholipase D signaling pathway. The 10 down-regulated genes were enriched in telomere maintenance via semi-conservative replication, AGE-RAGE signaling pathway in diabetic complications, and insulin resistance pathway. In the PPI network of 20 up-regulated DEGs, there were 40 nodes and 84 edges, with an average node degree of 4.2. For the 10 down-regulated DEGs, we found a total of 30 nodes and 105 edges, with an average node degree of 7.0 and local clustering coefficient of 0.812. Among the 30 DEGs, 10 hub genes (CNOT6L, CNOT6, CNOT1, CNOT7, RQCD1, RFC2, PRIM1, RFC4, RFC5, and RFC1) were also identified through Cytoscape. CONCLUSIONS DEGs of T2DM may play an essential role in disease development and may be potential pathogeneses of T2DM.