Significant elevation of serum dipeptidyl peptidase-4 activity in young-adult type 1 diabetes

Linagliptin in combination with insulin suppresses apoptotic unfolded protein response in ovaries exposed to type 1 diabetes

Type 1 diabetes mellitus (T1DM) is one of the main causes of ovarian atresia, but its molecular effect on the ovaries is not fully understood. Accumulating evidence suggests that T1DM causes excessive endoplasmic reticulum (ER) stress and insufficient adaptive unfolded protein response that triggers proapoptotic signaling pathways in ovarian tissue. In addition, problems such as amenorrhea and infertility, which are frequently seen in women with T1DM, continue despite the intensification of insulin therapy and improvement of metabolic control. Therefore new, and adjunctive treatments for women with T1DM need to be explored. We aimed to examine how the use of linagliptin, which has blood sugar-lowering effects and high antioxidant activity, together with insulin affects the expression levels of proteins and genes that play a role in ER stress in type 1 diabetic mouse ovaries. Eighty-four Balb/C 6-week-old female mice were randomly divided into seven groups: control, vehicle, diabetes + insulin, diabetes + linagliptin, diabetes + linagliptin + insulin, diabetes + TUDCA, and diabetes + TUDCA + insulin. TUDCA (an inhibitor of ER stress) groups are positive control groups created to compare linagliptin groups in terms of ER stress. Linagliptin and TUDCA were given by oral gavage and 1U insulin was administered subcutaneously for 2 weeks. A significant decrease was observed in the MDA and NOX1 levels and the number of atretic follicles in the ovaries of the diabetes + linagliptin + insulin group compared to the diabetes + insulin group. The use of linagliptin and insulin increased the expression of pro-survival XBP1s transmembrane protein and decreased the expression of proapoptotic ATF4, pJNK1/2, cleaved caspase 12, and cleaved caspase 3 in mouse ovaries. Our study provides new therapeutic evidence that linagliptin administered in addition to insulin induces ER stress mechanism-dependent survival in ovaries with type 1 diabetes.

Characteristic changes in plasma glutamate levels and free amino acid profiles in Japanese patients with type 1 diabetes mellitus

AIMS/INTRODUCTION

In addition to absolute insulin deficiency, dysregulated glucagon in type 1 diabetes is considered pathophysiologically important. Previously, we confirmed the presence of dysregulated glucagon in Japanese patients with type 1 diabetes, and found a significant correlation between plasma glucagon and blood urea nitrogen levels, suggesting an association between glucagon and amino acid metabolism. In this study, we evaluated plasma amino acid levels in Japanese patients with type 1 diabetes in the context of their functional relationship with glucagon.

MATERIALS AND METHODS

We assessed plasma free amino acid levels using liquid chromatography-mass spectrometry in 77 Japanese patients with type 1 diabetes, and statistically analyzed their characteristics and relationships with clinical parameters, including glucagon.

RESULTS

Participants with type 1 diabetes showed a large decrease in glutamate levels together with a characteristic change in plasma free amino acid profiles. The network structural prediction analyses showed correlations between each amino acid and glucagon in type 1 diabetes.

CONCLUSIONS

Participants with type 1 diabetes showed characteristic changes in plasma glutamate levels and free amino acid profiles compared with controls and type 2 diabetes patients. Glucagon showed a closer correlation with amino acids than with parameters of glucose metabolism, suggesting that type 1 diabetes includes dysregulation in amino acids through dysregulated glucagon from remaining pancreatic α-cells, together with that in glucose by insulin deficiency.

Emerging Role of Dipeptidyl Peptidase-4 in Autoimmune Disease

Dipeptidyl-peptidase IV (DPP4), originally identified as an aminopeptidase in 1960s, is an ubiquitously expressed protease presented as either a membrane-bound or soluble form. DPP4 cleaves dipeptide off from the N-terminal of its substrates, altering the bioactivity of its substrates. Subsequent studies reveal that DPP4 is also involved in various cellular processes by directly binding to a number of ligands, including adenosine deaminase, CD45, fibronectin, plasminogen, and caveolin-1. In recent years, many novel functions of DPP4, such as promoting fibrosis and mediating virus entry, have been discovered. Due to its implication in fibrotic response and immunoregulation, increasing studies are focusing on the potential role of DPP4 in inflammatory disorders. As a moonlighting protein, DPP4 possesses multiple functions in different types of cells, including both enzymatic and non-enzymatic functions. However, most of the review articles on the role of DPP4 in autoimmune disease were focused on the association between DPP4 enzymatic inhibitors and the risk of autoimmune disease. An updated comprehensive summary of DPP4’s immunoregulatory actions including both enzymatic dependent and independent functions is needed. In this article, we will review the recent advances of DPP4 in immune regulation and autoimmune rheumatic disease.

Dipeptidyl peptidase-4 inhibitor-induced autoimmune diseases: Current evidence

Dipeptidyl peptidase-4 inhibitors (DPP-4i) have an important place in the management of type 2 diabetes. The DPP-4 enzyme is ubiquitously distributed throughout the human body and has multiple substrates through which it regulates several important physiological functions. DPP-4 regulates several immune functions, including T-cell activation, macrophage function, and secretion of cytokines. Studies have reported an increase in autoimmune diseases like bullous pemphigoid, inflammatory bowel disease, and arthritis with DPP-4i use. The relationship of DPP-4i and autoimmune diseases is a complex one and warrants further research into the effect of DPP-4 inhibition on the immune system to understand the pathogenesis more clearly. Whether a particular cluster of autoimmune diseases is associated with DPP-4i use remains an important contentious issue. Nevertheless, a heightened awareness from the clinicians is required to identify and treat any such diseases. Through this review, we explore the clinical and pathophysiological characteristics of this association in light of recent evidence.

Combination of vitamin D and dipeptidyl peptidase-4 inhibitors (VIDPP-4i) as an immunomodulation therapy for autoimmune diabetes

Type 1 diabetes (T1D) and latent autoimmune diabetes in adults (LADA) represent the most common types of autoimmune diabetes and are characterized by different age of onset, degrees of immune-mediated destruction of pancreatic beta cells and rates of disease progression towards insulin dependence. Several immunotherapies aimed to counteract autoimmune responses against beta cells and preserve beta-cell function are currently being investigated, particularly in T1D. Preliminary findings suggest a potential role of combination therapy with vitamin D and dipeptidyl peptidase-4 (DPP-4) inhibitors (VIDPP-4i) in preserving beta-cell function in autoimmune diabetes. This manuscript aims to provide a comprehensive overview of the immunomodulatory properties of vitamin D and DPP-4 inhibitors, as well as the rationale for investigation of their combined use as an immunomodulation therapy for autoimmune diabetes.

Emerging Roles of Dipeptidyl Peptidase-4 Inhibitors in Delaying the Progression of Type 1 Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) results from the immune cell-mediated destruction of functional pancreatic β-cells. In the presymptomatic period, T1DM is characterized by the presence of two or more autoantibodies against the islet cells in patients without glycemic decompensation. Therapeutic strategies that can modify the autoimmune process could slow the progression of T1DM. Dipeptidyl peptidase-4 (DPP-4) or CD26, a multifunctional serine protease with a dual function (regulatory protease and binding protein), can modulate inflammation and immune cell-mediated β-cell destruction. CD26 is involved in T-cell co-stimulation, migration, memory development, thymic maturation, and emigration patterns. DPP-4 degrades the peptide hormones GLP-1 and GIP. In addition to regulating glucose metabolism, DPP-4 exerts anti-apoptotic, regenerative, and proliferative effects to promote β-cell mass expansion. GLP-1 receptor signaling may regulate murine lymphocyte proliferation and maintenance of peripheral regulatory T-cells. In patients with T1DM, the serum DPP-4 activity is upregulated. Several studies have suggested that the upregulated DPP-4 activity is correlated with T1DM pathophysiology. DPP-4, which is preferentially expressed on the Th1 surface, can promote the polarization of Th1 immunity, a prerequisite for T1DM development. CD26 inhibition can suppress T-cell proliferation and Th1 cytokine production and stimulate tumor growth factor beta-1 (TGF-β1) secretion, which plays an important role in the regulation of autoimmunity in T1DM. Studies on humans or animal models of T1DM have suggested that DPP-4 inhibitors can improve β-cell function and attenuate autoimmunity in addition to decreasing insulin dependence. This review summarizes the emerging roles of DPP-4 inhibitors in potentially delaying the progression of T1DM.

Serum Dipeptidyl peptidase-4 level is related to adiposity in type 1 diabetic adolescents

BACKGROUND

Insulin resistance (IR) plays a great role in type 1 diabetes (T1DM) disease process than is commonly recognized. Dipeptidyl peptidase-4 (DPP-4) is an enzyme that deactivates many bioactive peptides involved in glucose regulation.

AIMS

This study evaluates DPP-4 level in adolescent patients with T1DM compared to controls and investigates the relationship between DPP-4 level and IR in these patients.

MATERIALS AND METHODS

We measured serum DPP-4 level in 50 patients with T1DM recruited from the Diabetes Endocrine Metabolism Pediatric Unit, and in 80 healthy controls. IR was assessed by the equation for estimated glucose disposal rate (eGDR). Biochemical evaluation including glycated haemoglobin (HbA1C) and lipid profile were included.

RESULTS

IR was found in 80% of patients with T1DM. DPP-4 was significantly higher in control group than patients with T1DM. Patients with T1DM were classified into 3 groups according to DPP-4 tertiles showing significant increase in BMI SDS and total cholesterol across the 3 groups. Significant correlation was found between DPP-4 levels and insulin dose. DPP-4 was significantly higher in patients with T1DM with good glycemic control.

CONCLUSION

In sample of individuals researched by us, serum DPP-4 was related to adiposity and not to the hyperglycemia in patients with T1DM. Larger sample should be researched to make firm conclusions.

Plasma lipopolysaccharide binding protein level statistically mediates between body mass index and chronic microinflammation in Japanese patients with type 1 diabetes

Recently, it is widely recognized that microinflammation plays important roles in the pathophysiology of metabolic diseases, especially obesity-related disorders, diabetes and their complications. Lipopolysaccharide-binding protein (LBP) is a liver-derived acute-phase protein responsive to lipopolysaccharides (LPS) produced by gram-negative bacteria, thus reflects the systemic inflammation caused by the infection of those bacteria including gut dysbiosis. In this study, we evaluated the plasma LBP levels and investigated its clinical significance in 67 Japanese patients with type 1 diabetes. Univariable analysis showed that LBP levels were significantly associated with body mass index (BMI; r = 0.43, p < 0.01) and serum high-sensitivity C-reactive protein (hs-CRP; r = 0.64, p < 0.001) levels. However, there was no significant association between plasma LBP levels and diabetic complications. Mediation analysis revealed that LBP had significant mediation effects on the association between hs-CRP and BMI (0.27 [95% confidence interval 0.10-0.48]). These results suggest that the systemic condition where the LBP level increases, such as gut dysbiosis, at least partly, impacts on chronic microinflammation in patients with type 1 diabetes.

Consistency of plasma glucagon levels in patients with type 1 diabetes after a 1-year period

Recent progress in research on glucagon and α-cells highlights their pathophysiological roles in diabetes. We previously showed that plasma glucagon levels measured by newly developed enzyme-linked immunosorbent assay were dysregulated in patients with type 1 diabetes with respect to plasma glucose levels, suggesting dysregulated secretion. In the current study, the annual change in plasma glucagon levels was assessed in these same patients. We found that the plasma glucagon levels in the 66 Japanese patients involved in the study were significantly correlated between both years. In addition, they were significantly associated with serum blood urea nitrogen levels in a multivariate linear regression analysis, as reported in our previous study. The statistical correlation in glucagon levels between annual checkups and the sustained significant correlation between glucagon and blood urea nitrogen suggest a constant dysregulation of glucagon in association with altered amino acid metabolism in patients with type 1 diabetes.

Neuropeptide Y system mRNA expression changes in the hippocampus of a type I diabetes rat model

BACKGROUND

Neuropeptide Y (NPY) plays a crucial role in many neurobiological functions, such as cognition and memory. Cognitive and memory impairment have been described in diabetic patients. The metabolism of NPY is determined by the activity of proteases, primarily dipeptidyl-peptidase-IV (DPP-IV). Therefore, DPP-IV inhibitors, such as sitagliptin, may modulate the function of NPY. In this study, we investigated the effect of type 1 diabetes and sitagliptin treatment on the regulation of the mRNA encoding for NPY and its receptors (Y1, Y2, and Y5 receptors) in the hippocampus.

METHODS

Type 1 diabetes was induced in male Wistar rats by i.p. injection of streptozotocin. Starting two weeks after diabetes onset, animals were treated orally with sitagliptin (5mg/kg, daily) for two weeks. The mRNA expression of Npy and its receptors (Npy1r, Npy2r, and Npy5r) in the hippocampus was evaluated using in situ hybridization with ³³P-labeled oligonucleotides.

RESULTS

The mRNA expression of Npy, Npy1r and Npy5r was higher in the dentate gyrus, whereas Npy2r highest level was observed in the CA3 subregion. The mRNA expression of Npy, Npy1r and Npy5r in dentate gyrus, CA1 and CA3 was not affected by diabetes and/or by sitagliptin treatment. Type 1 diabetes increased the mRNA expression of Npy2r in the CA3 subregion, which was prevented by sitagliptin treatment.

CONCLUSIONS

Our results show that type 1 diabetes, at early stages, induces mild changes in the NPY system in the hippocampus that were counteracted by sitagliptin treatment.

CD26 in autoimmune diseases: The other side of "moonlight protein"

Dipeptidyl peptidase 4 (DPP-4) is a serine protease, which has enzymatic activity to selectively clean the N-terminal dipeptide of peptides and proteins with proline or alanine in the second position. DPP-4 inhibitor has been widely used for the treatment of type 2 diabetes by increasing the level of the glucagon-like peptide-1 and decreasing the glucose level. DPP-4, also known as lymphocyte cell surface protein CD26, plays a core role of T cell immunity. Many roles of CD26 in other immune cells have been found. As a "moonlight protein", the effect of CD26 in autoimmune diseases has attracted more and more attention. The paper reviewed the function and potential effect of CD26 in autoimmune diseases, which shows CD26 may be a new target of autoimmune diseases deserved further study.

The impact of the glucagon-like peptide 1 receptor agonist liraglutide on the streptozotocin-induced diabetic mouse kidney proteome

In diabetes mellitus (DM), the kidneys are exposed to increased levels of hyperglycemia-induced oxidative stress. Elevated amounts of reactive oxygen species (ROS) are believed to provoke ultrastructural changes in kidney tissue and can eventually result in DM late complications such as diabetic nephropathy. While it is reported that glucagon-like peptide 1 receptors (GLP-1R) are present in the kidney vasculature, the effects of GLP-1 on the kidney proteome in DM is not well described. Thus, we set out to investigate potential effects on the proteomic level. Here the effects of GLP-1R agonism using the GLP-1 analogue liraglutide are studied in the kidneys of streptozotocin (STZ)-treated mice (n = 6/group) by label-free shotgun mass spectrometry (MS) and targeted MS. Unsupervised and supervised multivariate analyses are followed by one-way ANOVA. Shotgun MS data of vehicle and liraglutide-treated mouse groups are separated in the supervised multivariate analysis and separation is also achieved in the subsequent unsupervised multivariate analysis using targeted MS data. The mouse group receiving the GLP-1R agonist liraglutide has increased protein abundances of glutathione peroxidase-3 (GPX3) and catalase (CATA) while the abundances of neuroplastin (NPTN) and bifunctional glutamate/proline-tRNA ligase (SYEP) are decreased compared to the STZ vehicle mice. The data suggest that GLP-1R agonism mainly influences abundances of structurally involved proteins and proteins involved in oxidative stress responses in the STZ mouse kidney. The changes could be direct effects of GLP-1R agonism in the kidneys or indirectly caused by a systemic response to GLP-1R activation.

Role of Milk-Derived Opioid Peptides and Proline Dipeptidyl Peptidase-4 in Autism Spectrum Disorders

Opioid peptides released during digestion of dietary proteins such as casein, were suggested to contribute to autism development, leading to the announcement of opioid excess hypothesis of autism. This paper examines role of enzyme proline dipeptidyl peptidase-4 (DPPIV; EC 3.4.14.5) and it is exogenous substrate, β-casomorphin-7 (BCM7) in autism etiology. Our study included measurements of DPPIV and BCM7 concentrations in serum and urine, which were analyzed with ELISA assays and activity of DPPIV was measured by colorimetric test. The effect of opioid peptides from hydrolysed bovine milk on DPPIV gene expression in peripheral blood mononuclear cells (PBMC) in autistic and healthy children was determined using the Real-Time PCR (Polymerase Chain Reaction) method. Our research included 51 healthy children and 86 children diagnosed with autism spectrum disorder (ASD, ICDF84). We determined that the concentration of BCM7 in serum was significantly, 1.6-fold, higher in the ASD group than in controls (p < 0.0001). Concentration of DPPIV was found to also be significantly higher in serum from ASD children compared to the control group (p < 0.01), while we did not notice significant difference in enzymatic activity of serum DPPIV between the two study groups. We confirmed correlation according to the gender between analyzed parameters. The inspiration for this study emanated from clinical experience of the daily diet role in relieving the symptoms of autism. Despite this, we have concluded that milk-derived opioid peptides and DPPIV are potentially factors in determining the pathogenesis of autism; conducted studies are still limited and require further research.

Dysregulated plasma glucagon levels in Japanese young adult type 1 diabetes patients

Currently, the clinical dynamics of glucagon need to be revised based on previous data obtained from conventional glucagon radioimmunoassays. In the present study, we evaluated plasma glucagon levels in type 1 diabetes patients using a newly-developed sandwich enzyme-linked immunosorbent assay, and its association with clinical parameters and markers of diabetes complications were statistically assessed. The plasma glucagon level in 77 Japanese type 1 diabetes patients was 28.1 ± 17.7 pg/mL, and comparable with that reported previously for type 2 diabetes patients. However, the values were widely spread and did not correlate with plasma glucose values. Additionally, the average glucagon levels in patients in a hypoglycemic state (glucose level <80 mg/dL) did not increase (21.7 ± 12.2 pg/mL). The average glucagon level of patients experiencing hypoglycemia unawareness was significantly lower. Plasma glucagon levels evaluated using the new enzyme-linked immunosorbent assay were dysregulated in type 1 diabetes patients in respect to plasma glucose levels, suggesting dysregulation of secretion.

DPP-4 Inhibitors as Treatments for Type 1 Diabetes Mellitus: A Systematic Review and Meta-Analysis

OBJECTIVE

Several clinical studies have reported the application of dipeptidyl peptidase-4 (DPP-4) inhibitors as treatments for type 1 diabetes mellitus (T1DM). This study aims to review the outcomes of these existing studies and to discuss the therapeutic effects of DPP-4 inhibitors on T1DM.

METHODS

We thoroughly searched the Medline, Embase, PubMed, and Cochrane Library databases and ClinicalTrials.gov for studies concerning the use of DPP-4 inhibitors in patients with T1DM.

RESULTS

In preclinical trials, DPP-4 inhibitors improved the pathogenesis of T1DM. However, only a portion of the studies showed potential efficacy regarding clinical glycemic control and other clinical parameters. From this meta-analysis, pooled data from 5 randomized controlled trials revealed that the additional use of DPP-4 inhibitors resulted in a greater decrease in glycated hemoglobin A1c (HbA1c) levels (0.07%, 95% CI (-0.37%-0.23%)) than insulin monotherapy, although the decrease was not significant. A small decrease in postprandial glucose or insulin consumption was confirmed.

CONCLUSION

Although DPP-4 inhibitors may be beneficial for T1DM, existing studies do not strongly support these positive effects in clinical practice. Further optimized clinical trials are needed.

Exploring the molecular mechanisms underlying α- and β-cell dysfunction in diabetes

Pancreatic islet dysfunction, including impaired insulin secretion in β cells and dysregulated glucagon secretion in α cells, is the chief pathology of diabetes. In β cells, oxidative stress, evoked by chronic hyperglycemia, was found to induce dysfunction of a critical transcription factor, PDX1, caused by its nucleocytoplasmic translocation via interactions with the insulin and JNK signaling pathways and another transcription factor, FOXO1. The significance of α-cell insulin signaling in the physiological and pathological regulation of α-cell biology was demonstrated in α-cell-specific insulin receptor knockout mice, which exhibited dysregulated glucagon secretion. Moreover, a high-glucose load directly induced excessive glucagon secretion in a glucagon-secreting cell line and isolated islets, together with impairment of insulin signaling. These findings indicate that disordered insulin signaling is central to the pathophysiology of islet dysfunction in both α and β cells. On the other hand, certain beneficial effects of GLP-1 on dysfunctional α and β cells indicate that it has therapeutic potential for diabetes patients who exhibit insulin resistance in islets. These studies, involving basic medical research approaches, have-at least in part-clarified the molecular mechanisms underlying α- and β-cell dysfunction in diabetes, and offer important clues that should aid the development of future therapeutic approaches to the disease.

Influence of nutritional intervention on children with type 1 diabetes mellitus and DPP-4 in serum

The level of dipeptidyl peptidase-4 (DPP-4) of children with type 1 diabetes mellitus (T1DM) was observed to evaluate the improvement in function of the nutritional intervention. In total, 132 children with T1DM (T1DM group) and 132 healthy children (NC group) based on physical examination admitted to our hospital from September 2014 to June 2015 and were studied. General data of the two groups as well as the concentration of DPP-4 and various biochemical criterion in peripheral serum were collected and analyzed. Compared with NC group, DPP-4 level of T1DM group was obviously increased (P<0.05); after insulin treatment, the serum level of DPP-4 of T1DM group decreased, but was still significantly higher than that of NC group (P<0.05). After 3 months of clinical nutritional intervention, body mass index (BMI) of children with T1DM was significantly reduced compared with data before the treatment (P<0.05). However, the level of DPP-4 appeared unchanged (P>0.05). Pearson's correlation analysis showed that the level of DPP-4 had a positive correlation with diabetic duration, BMI and gamma (γ)-glutamyl transpeptidase for children suffering TIDM (P<0.05). Multiple linear regression analysis showed that BMI may be a factor influencing DPP-4 level in serum of T1DM children. In conclusion, the level of DPP-4 in serum increased, and insulin treatment was able to decrease DPP-4 level in T1DM children. However, clinical nutritional intervention could not improve the level of DPP-4 and BMI may be an influental factor of the DPP-4 level.

Hepatic Dipeptidyl Peptidase-4 Controls Pharmacokinetics of Vildagliptin In Vivo

The main route of elimination of vildagliptin, which is an inhibitor of dipeptidyl peptidase-4 (DPP-4), in humans is cyano group hydrolysis to produce a carboxylic acid metabolite M20.7. Our in vitro study previously demonstrated that DPP-4 itself greatly contributed to the hydrolysis of vildagliptin in mouse, rat, and human livers. To investigate whether hepatic DPP-4 contributes to the hydrolysis of vildagliptin in vivo, in the present study, we conducted in vivo pharmacokinetics studies of vildagliptin in mice coadministered with vildagliptin and sitagliptin, which is another DPP-4 inhibitor, and also in streptozotocin (STZ)-induced diabetic mice. The area under the plasma concentration-time curve (AUC) value of M20.7 in mice coadministered with vildagliptin and sitagliptin was significantly lower than that in mice administered vildagliptin alone (P < 0.01). Although plasma DPP-4 expression level was increased 1.9-fold, hepatic DPP-4 activity was decreased in STZ-induced diabetic mice. The AUC values of M20.7 in STZ-induced diabetic mice were lower than those in control mice (P < 0.01). Additionally, the AUC values of M20.7 significantly positively correlated with hepatic DPP-4 activities in the individual mice (Rs = 0.943, P < 0.05). These findings indicated that DPP-4 greatly contributed to the hydrolysis of vildagliptin in vivo and that not plasma, but hepatic DPP-4 controlled pharmacokinetics of vildagliptin. Furthermore, enzyme assays of 23 individual human liver samples showed that there was a 3.6-fold interindividual variability in vildagliptin-hydrolyzing activities. Predetermination of the interindividual variability of hepatic vildagliptin-hydrolyzing activity might be useful for the prediction of blood vildagliptin concentrations in vivo.

Incretin-Based Therapies for Diabetic Complications: Basic Mechanisms and Clinical Evidence

An increase in the rates of morbidity and mortality associated with diabetic complications is a global concern. Glycemic control is important to prevent the development and progression of diabetic complications. Various classes of anti-diabetic agents are currently available, and their pleiotropic effects on diabetic complications have been investigated. Incretin-based therapies such as dipeptidyl peptidase (DPP)-4 inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1RA) are now widely used in the treatment of patients with type 2 diabetes. A series of experimental studies showed that incretin-based therapies have beneficial effects on diabetic complications, independent of their glucose-lowering abilities, which are mediated by anti-inflammatory and anti-oxidative stress properties. Based on these findings, clinical studies to assess the effects of DPP-4 inhibitors and GLP-1RA on diabetic microvascular and macrovascular complications have been performed. Several but not all studies have provided evidence to support the beneficial effects of incretin-based therapies on diabetic complications in patients with type 2 diabetes. We herein discuss the experimental and clinical evidence of incretin-based therapy for diabetic complications.