Impaired incretin effect is an early sign of glucose dysmetabolism in nondiabetic patients with psoriasis

Oral glucose has little or no effect on appetite and satiety sensations despite a significant gastrointestinal response

OBJECTIVE

The effect of oral glucose-induced release of gastrointestinal hormones on satiety and appetite independently of prevailing plasma glucose excursions is unknown. The objective is to investigate the effect of oral glucose on appetite and satiety sensations as compared to isoglycemic IV glucose infusion (IIGI) in healthy volunteers.

DESIGN

A crossover study involving two study days for each participant.

PARTICIPANTS

Nineteen healthy participants (6 women, mean age 55.1 [SD 14.2] years; mean body mass index 26.7 [SD 2.2] kg/m2).

INTERVENTIONS

Each participant underwent a 3-h 50-g oral glucose tolerance test (OGTT) and, on a subsequent study day, an IIGI mimicking the glucose excursions from the OGTT. On both study days, appetite and satiety were indicated regularly on visual analog scale (VAS), and blood was drawn regularly for measurement of pancreatic and gut hormones.

PRIMARY OUTCOMES

Difference in appetite and satiety sensations during OGTT and IIGI.

RESULTS

Circulating concentrations of glucose-dependent insulinotropic polypeptide (P < .0001), glucagon-like peptide 1 (P < .0001), insulin (P < .0001), C-peptide (P < .0001), and neurotensin (P = .003) increased significantly during the OGTT as compared to the IIGI, whereas glucagon responses were similarly suppressed (P = .991). Visual analog scale-assessed ratings of hunger, satiety, fullness, thirst, well-being, and nausea, respectively, were similar during OGTT and IIGI whether assessed as mean 0-3-h values or area under the curves. For both groups, a similar, slow increase in appetite and decrease in satiation were observed. Area under the curve, for prospective food consumption (P = .049) and overall appetite score (P = .044) were slightly lower during OGTT compared to IIGI, whereas mean 0-3-h values were statistically similar for prospective food consumption (P = .053) and overall appetite score (P = .063).

CONCLUSIONS

Despite eliciting robust responses of appetite-reducing and/or satiety-promoting gut hormones, we found that oral glucose administration has little or no effect on appetite and satiety as compared to an IIGI, not affecting the release of appetite-modulating hormones.

TRIAL REGISTRY NO

ClinicalTrials.gov: NCT01492283 and NCT06064084.

Exploring the molecular mechanism underlying the psoriasis and T2D by using microarray data analysis

Although a large number of evidence has identified that psoriasis is significantly correlated with type 2 diabetes (T2D), the common molecular mechanism of its occurrence remains unclear. Our study aims to further elucidate the mechanism of the occurrence of this complication. We obtained the gene expression data of psoriasis (GSE30999) and T2D (GSE28829) from the Gene Expression Omnibus (GEO) dataset. Then the common differentially expressed genes (DEGs) of T2D and psoriasis were identified. After that, we performed three types of analyses about these DEGs, including functional enrichment analysis, protein-protein interaction (PPI) network and module manufacture, hub genes identification and co-expression analysis. 132 common DEGs (14 upregulated genes and 118 downregulated genes) were identified for subsequent a series of analyses. Function enrichment analysis demonstrated that Rap1 signaling pathway, PI3K-Akt signaling pathway, and cGMP-PKG signaling pathway may play a significant role in pathogenesis of psoriasis and T2D. Finally, 3 important hub genes were selected by utilizing cytoHubba, including SNRPN, GNAS, IGF2. Our work reveals the potential common signaling pathways of psoriasis and T2D. These Hub genes and common signaling pathways provide insights for further investigation of molecular mechanism about psoriasis and T2D.

Efficacy of ixekizumab in patients with moderate-to-severe plaque psoriasis and prediabetes or type 2 diabetes

Objective

Patients with psoriasis have an increased prevalence of type 2 diabetes when compared to the general population. Research suggests that type 2 diabetes (T2D) as well as obesity may have an impact on patients' response to treatment. This post-hoc analysis reports the efficacy of ixekizumab in treating moderate-to-severe psoriasis in patients with prediabetes or T2D.

Method and materials

UNCOVER-1, UNCOVER-2, and UNCOVER-3 were three Phase 3, multicenter, randomized, double-blind, placebo-controlled trials that evaluated the efficacy and safety of ixekizumab in adult patients with moderate-to-severe psoriasis. Patients were aged ≥18 years with chronic moderate-to-severe psoriasis (defined as ≥10% body surface area affected, static Physician Global Assessment ≥3, and Psoriasis Area and Severity Index [PASI] ≥12 at screening and baseline) who were candidates for phototherapy or systemic therapy. UNCOVER-1, UNCOVER-2, and UNCOVER-3 participants received ixekizumab as per label (that is, an initial dose of two subcutaneous injections [160 mg in total] at Week 0, followed by 80 mg every 2 weeks through Week 12 and 80 mg every 4 weeks thereafter through Week 60).

Results

The proportions of patients with prediabetes, T2D and normoglycemia that achieved PASI75, PASI90, and PASI100 at Week 60 were similar. Results suggest that patients with T2D were slower to achieve PASI100 than patients with prediabetes or those with normoglycemia. Ixekizumab had no effect on any metabolic markers in patients receiving the treatment.

Conclusions

Despite the higher rate of obesity and extreme obesity in patients with prediabetes and T2D, ixekizumab was an efficacious treatment in treating patients with psoriasis.

Loss of the Incretin Effect in Type 2 Diabetes: A Systematic Review and Meta-analysis

CONTEXT

Loss of the incretin effect (IE) in type 2 diabetes (T2D) contributes to hyperglycemia and the mechanisms underlying this impairment are unclear.

OBJECTIVE

To quantify the IE impairment in T2D and to investigate the factors associated with it using a meta-analytic approach.

METHODS

PubMed, Scopus, and Web-of-Science were searched. Studies measuring IE by the gold-standard protocol employing an oral glucose tolerance test (OGTT) and an intravenous glucose infusion at matched glucose levels were selected. We extracted IE, sex, age, body mass index (BMI), and hemoglobin A1c, fasting values, and area under curve (AUC) of glucose, insulin, C-peptide, glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide 1 (GLP-1). In subjects with T2D, we also recorded T2D duration, age at diagnosis, and the percentage of subjects taking antidiabetic medications.

RESULTS

The IE weighted mean difference between subjects with T2D and those with normal glucose tolerance (NGT) was -27.3% (CI -36.5% to -18.1%; P < .001; I2 = 86.6%) and was affected by age (P < .005). By meta-regression of combined NGT and T2D data, IE was inversely associated with glucose tolerance (lower IE in T2D), BMI, and fasting GIP (P < .05). By meta-regression of T2D studies only, IE was associated with the OGTT glucose dose (P < .0001). IE from insulin was larger than IE from C-peptide (weighted mean difference 11.2%, CI 9.2-13.2%; P < .0001; I2 = 28.1%); the IE difference was inversely associated with glucose tolerance and fasting glucose.

CONCLUSION

The IE impairment in T2D vs NGT is consistent though considerably variable, age being a possible factor affecting the IE difference. Glucose tolerance, BMI, and fasting GIP are independently associated with IE; in subjects with T2D only, the OGTT dose is a significant covariate.

The role of incretins and incretin-based drugs in autoimmune diseases

Incretin hormones, including glucagon-like peptide (GLP)-1, GLP-2 and glucose-dependent insulinotropic polypeptide (GIP), are gastrointestinal peptides secreted from enteroendocrine cells. These hormones play significant roles in many physiological processes via binding to G-protein coupled receptors (GPCRs) on different organs and tissues; one of them is the immunomodulatory effect on the immune system and its molecular components such as cytokines and chemokines. Anti-inflammatory effects of incretins and dependent molecules involving long-acting analogs and DPP4 inhibitors through regulation of T and B cell activation may attenuate autoimmune diseases caused by immune system disorders in mistakenly recognizing self as the foreign agent. In this review, we investigate incretin effects on the immune system response and the potential benefits of incretin-based therapy for treating autoimmune diseases.

Psoriasis and Diabetes, a Dangerous Association: Evaluation of Insulin Resistance, Lipid Abnormalities, and Cardiovascular Risk Biomarkers

Aims: Psoriasis is an immune-mediated dermatosis with cardio-metabolic comorbidities. The aim of this study was to assess insulin-resistance, lipid abnormalities, and cardiovascular risk biomarkers in psoriatic patients with or without type 2 diabetes mellitus (T2DM).

Methods and materials: We enrolled 425 patients: 86 psoriatics, 69 psoriatics with T2DM, 120 T2DM patients, and 150 healthy subjects. We measured the Psoriasis Area and Severity Index (PASI), body mass index (BMI), insulin-resistance parameters [glycosylated hemoglobin (HbA_1c), fasting plasma glucose (FPG), fasting plasma insulin (FPI), and with homeostasis model assessment index (HOMA index)], lipidic panel, plasminogen activator inhibitor-1 (PAI-1), homocysteine, soluble adhesion molecules, matrix metalloproteinase, and adipocytokines.

Results: FPG, HbA_1c, and HOMA-IR were higher in diabetics with psoriasis (p < 0.0001) than in psoriatics. FPI levels were higher in diabetics with psoriasis than in diabetics and psoriatics (p < 0.0001), and higher in psoriatics than controls (p < 0.0001). Psoriatics and diabetics with psoriasis showed higher triglyceride and LDL-C levels (p < 0.0001) than diabetics. Homocysteine was higher in psoriatics and diabetics with psoriasis (p < 0.0001) than in diabetics. PAI-1 was higher in diabetics with psoriasis than diabetics (p < 0.01). sICAM-1 and sVCAM-1 were higher in diabetics with psoriasis than diabetics (p < 0.001 and p < 0.01) and psoriatics (p < 0.001 and p < 0.0001). Visfatin and resistin were lower in psoriatics (p < 0.0001) and in diabetics with psoriasis (p < 0.001 and p < 0.0001, respectively) than diabetics.

Conclusions: A limitation of this study is that there is a significant difference in mean age between controls and other study groups: the lack of matching between case and control groups may interfere with the external validity of the study findings. Despite this, the study highlights a pathogenetic link between psoriasis, considered a pre-diabetic condition, and diabetes. Insulin-resistance seems to be the keystone of psoriasis comorbidities. Psoriasis reinforces diabetes, causing a greater cardiometabolic risk.

The Diabetes Syndrome - A Collection of Conditions with Common, Interrelated Pathophysiologic Mechanisms

The four basic pathophysiologic mechanisms which damage the β-cell within diabetes (ie, genetic and epigenetic changes, inflammation, an abnormal environment, and insulin resistance [IR]) also contribute to cell and tissue damage and elevate the risk of developing all typical diabetes-related complications. Genetic susceptibility to damage from abnormal external and internal environmental factors has been described including inflammation and IR. All these mechanisms can promote epigenetic changes, and in total, these pathophysiologic mechanisms interact and react with each other to cause damage to cells and tissues ultimately leading to disease. Importantly, these pathophysiologic mechanisms also serve to link other common conditions including cancer, dementia, psoriasis, atherosclerotic cardiovascular disease (ASCVD), nonalcoholic fatty liver disease (NAFLD), and nonalcoholic steatohepatitis (NASH). The "Diabetes Syndrome", an overarching group of interrelated conditions linked by these overlapping mechanisms, can be viewed as a conceptual framework that can facilitate understanding of the inter-relationships of superficially disparate conditions. Recognizing the association of the conditions within the Diabetes Syndrome due to common pathophysiologies has the potential to provide both benefit to the patient (eg, prevention, early detection, precision medicine) and to the advancement of medicine (eg, driving education, research, and dynamic decision-based medical practice).

Psoriasis Exacerbates the State of Insulin Resistance in Patients with Type 2 Diabetes

PURPOSE

Although psoriasis (PsO) is highly associated with insulin resistance (IR), the role of PsO on activity of insulin secretion or its action in diabetic patients has not been explored.

MATERIALS AND METHODS

In-patient data on type 2 diabetes (T2D) with or without PsO from 2016-2019 in our hospital were analyzed. Data for 42 diabetic patients with PsO were compared with that of the control group (T2D only). Blood examinations with reference to the levels of fasting blood glucose, C-peptide, insulin, HbA1c, plasma lipids, lipoproteins, and kidney function were explored. HOMA-IR and HOMA-β models were established to explore IR and pancreatic β-cell function.

RESULTS

HOMA-IR level was significantly higher (P=0.0003<0.05) in patients with PsO compared with the controls. Although the durations of diabetes in patients with PsO were significantly shorter compared with that of patients with diabetes only (P=0.012<0.05), analysis of mean BMI, eGFR, plasma lipids, and lipoprotein showed no significant differences. Analysis of the level of fasting glucose and HOMA-β showed no statistical differences between the two groups. On the other hand, the levels of C-peptide of PsO group were significantly high in both fasting state (P=0.0182<0.05) and after glucose challenge (P=0.0011<0.01).

CONCLUSION

The findings of this study show that under the same fasting conditions, patients with PsO may have relatively preserved pancreatic β-cell function, and PsO significantly increases IR.

Causal Relationship and Shared Genetic Loci between Psoriasis and Type 2 Diabetes through Trans-Disease Meta-Analysis

Psoriasis and type 2 diabetes (T2D) are complex conditions with significant impacts on health. Patients with psoriasis have a higher risk of T2D (∼1.5 OR) and vice versa, controlling for body mass index; yet, there has been a limited study comparing their genetic architecture. We hypothesized that there are shared genetic components between psoriasis and T2D. Trans-disease meta-analysis was applied to 8,016,731 well-imputed genetic markers from large-scale meta-analyses of psoriasis (11,024 cases and 16,336 controls) and T2D (74,124 cases and 824,006 controls), adjusted for body mass index. We confirmed our findings in a hospital-based study (42,112 patients) and tested for causal relationships with multivariable Mendelian randomization. Mendelian randomization identified a causal relationship between psoriasis and T2D (P = 1.6 × 10^‒4, OR = 1.01) and highlighted the impact of body mass index. Trans-disease meta-analysis further revealed four genome-wide significant loci (P < 5 × 10^‒8) with evidence of colocalization and shared directions of effect between psoriasis and T2D not present in body mass index. The proteins coded by genes in these loci (ACTR2, ERLIN1, TRMT112, and BECN1) are connected through NF-κB signaling. Our results provide insight into the immunological components that connect immune-mediated skin conditions and metabolic diseases, independent of confounding factors.

Diabetes and Psoriasis: Different Sides of the Same Prism

Diabetes and psoriasis are prevalent conditions with a spectrum of serious adverse outcomes. Both diseases are common comorbidities for each other, and diabetes is considered as a risk factor for psoriasis and vice versa. However, it is our contention that these diseases are not merely comorbidities of each other but rather share common underlying pathophysiologies (ie, genes and epigenetic changes, inflammation, abnormal environment, and insulin resistance) that drive disease. As such, they can be viewed as facets of the same prism. Genes can cause or permit susceptibility to damage from abnormal external and internal environmental factors, inflammation, and insulin resistance which can also drive epigenetic changes. These co-existing mechanisms act in a vicious cycle over time to potentiate cell and tissue damage to ultimately drive disease. Viewing diabetes and psoriasis through the same prism suggests potential for therapies that could be used to treat both conditions. Although additional controlled trials and research are warranted, we believe that our understanding of the overlapping pathophysiologies continues to grow, so too will our therapeutic options.

Psoriasis and Cardiovascular Risk: A Comprehensive Review

Psoriasis is a systemic inflammatory disorder that involves complex pathogenic interactions between the innate and adaptive immune systems. Individuals with psoriasis have an increased risk of developing other chronic health diseases such cardiovascular disorders. The high incidence of cardiovascular events in the population with psoriasis could be explained by several mechanisms. The high prevalence of traditional cardiovascular risk factors and metabolic abnormalities contributes to the high cardiovascular burden in patients with psoriasis. Likewise, the presence of systemic inflammation in combination with metabolic abnormalities may act in a synergistic manner to increase cardiovascular risk in these patients. This review focused on epidemiologic and clinical evidence linking psoriasis to cardiovascular risk factors and cardiovascular disease. We described the possible pathophysiological mechanisms that justify this association and analyzed the best way to stratify the cardiovascular risk in patients with psoriasis. We also described the usefulness of the therapies frequently used in cardiovascular prevention and analyzed the impact of the specific psoriasis medication on cardiovascular risk factors or major atherosclerotic events. Knowledge of the application of different cardiovascular prevention strategies could mean an advantage in performing the difficult task of estimating cardiovascular risk and treating cardiovascular risk factors in this particular group of patients.

Evaluation of the incretin effect in humans using GIP and GLP-1 receptor antagonists

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) potentiate glucose-induced insulin secretion and are therefore thought to be responsible for the incretin effect. The magnitude of the incretin effect, defined as the fraction of postprandial insulin secretion stimulated by intestinal factors, has been reported to be up to ∼60% in healthy individuals. In several pathological conditions but especially in patients with type 2 diabetes, the incretin effect is severely reduced or even absent. In line with this, the insulinotropic effects of GIP and GLP-1 are impaired in patients with type 2 diabetes, even when administered in supraphysiological doses. In healthy individuals, GIP has been proposed to be the most important incretin hormone of the two, but the individual contribution of the two is difficult to determine. However, using incretin hormone receptor antagonists: the novel GIP receptor antagonist GIP(3-30)NH₂ and the widely used GLP-1 receptor antagonist exendin(9-39)NH₂, we can now distinguish between the effects of the two hormones. In this review, we present and discuss studies in which the individual contribution of GIP and GLP-1 to the incretin effect in healthy individuals have been estimated and discuss the limitations of using incretin hormone receptor antagonists.

Glucose metabolism in patients with psoriasis

BACKGROUND

Epidemiological studies strongly suggest that psoriasis predisposes to type 2 diabetes. Several theories have been proposed to explain how these disease entities might be pathophysiologically connected.

OBJECTIVES

Our primary objective was to elucidate whether clinical data support the notion of common pathophysiological denominators in patients with psoriasis and type 2 diabetes, and thus to delineate the association between the two conditions that has arisen on the basis of epidemiological studies.

METHODS

We reviewed clinical studies investigating parameters of glucose metabolism in patients with psoriasis. The PubMed and Embase databases were searched for studies investigating glucose metabolism in adult patients with psoriasis as a primary or secondary end point. Studies had to include a relevant control group.

RESULTS

Twenty-six clinical studies reporting on insulin resistance, glucose tolerance or insulin secretion were eligible for review. The results were widely conflicting, with less than half of the studies showing results suggestive of defective glucose metabolism in patients with psoriasis. In general, the studies suffered from a lack of information regarding possible confounders and patient characteristics. Furthermore, the research methods varied, and in all but one study they might not have been appropriate to detect early and subtle defects in glucose metabolism.

CONCLUSIONS

The available literature does not unequivocally support common pathophysiological denominators in psoriasis and type 2 diabetes. Well-designed clinical studies are needed to expose potential diabetogenic defects in the glucose metabolism in patients with psoriasis.

Determinants of Fasting Hyperglucagonemia in Patients with Type 2 Diabetes and Nondiabetic Control Subjects

BACKGROUND

Fasting hyperglucagonemia can be detrimental to glucose metabolism in patients with type 2 diabetes (T2D) and may contribute to metabolic disturbances in obese and/or prediabetic subjects. However, the mechanisms underlying fasting hyperglucagonemia remain elusive.

METHODS

We evaluated the interrelationship between fasting hyperglucagonemia and demographic and biochemical parameters in 106 patients with T2D (31% female, age: 57 ± 9 years [mean ± standard deviation; body mass index (BMI): 30.1 ± 4.4 kg/m²; fasting plasma glucose (FPG): 9.61 ± 2.39 mM; hemoglobin A1c (HbA1c): 57.1 ± 13.1 mmol/mol] and 163 nondiabetic control subjects (29% female; age: 45 ± 17 years; BMI: 25.8 ± 4.1 kg/m²; FPG: 5.2 ± 0.4 mM; and HbA1c: 35.4 ± 3.8 mmol/mol). Multiple linear regression analysis was applied using a stepwise approach with fasting plasma glucagon as dependent parameter and BMI, waist-to-hip ratio (WHR), blood pressure, hemoglobin A1c, FPG, and insulin concentrations as independent parameters.

RESULTS

Fasting plasma glucagon concentrations were significantly higher among patients with T2D (13.5 ± 6.3 vs. 8.5 ± 3.8 mM, P < 0.001) together with HbA1c (P < 0.001), FPG (P < 0.001), and insulin (84.9 ± 56.4 vs. 57.7 ± 35.3 mM, P < 0.001). When adjusted for T2D, HbA1c and insulin were significantly positive determinants for fasting plasma glucagon concentrations. Furthermore, WHR comprised a significant positive determinant.

CONCLUSIONS

We confirm that fasting plasma glucagon concentrations are abnormally high in patients with T2D, and show that fasting plasma glucagon concentrations are influenced by WHR (in addition to glycemic control and fasting plasma insulin concentrations), which may point to visceral fat deposition as an important determinant of increased fasting plasma glucagon concentrations.

EJE PRIZE 2018: A gut feeling about glucagon

Hyperglucagonaemia (in the fasting as well as in the postprandial state) is considered a core pathophysiological component of diabetes and is found to contribute substantially to the hyperglycaemic state of diabetes. Hyperglucagonaemia is usually viewed upon as a consequence of pancreatic alpha cell insensitivity to the glucagon-suppressive effects of glucose and insulin. Since we observed that the well-known hyperglucagonaemic response to oral glucose in patients with type 2 diabetes is exchanged by normal suppression of plasma glucagon levels following isoglycaemic intravenous glucose administration in these patients, we have been focusing on the gut and gut-derived factors as potential mediators of diabetic hyperglucagonaemia. In a series of clinical experiments, we have elucidated the role of gut-derived factors in diabetic hyperglucagonaemia and shown that glucose-dependent insulinotropic polypeptide promotes hyperglucagonaemia and that glucagon, hitherto considered a pancreas-specific hormone, may also be secreted from extrapancreatic tissues - most likely from proglucagon-producing enteroendocrine cells. Furthermore, our observation that fasting hyperglucagonaemia is unrelated to the diabetic state, but strongly correlates with obesity, liver fat content and circulating amino acids, has made us question the common 'pancreacentric' and 'glucocentric' understanding of hyperglucagonaemia and led to the hypothesis that steatosis-induced hepatic glucagon resistance (and reduced amino acid turnover) and compensatory glucagon secretion mediated by increased circulating amino acids constitute a complete endocrine feedback system: the liver-alpha cell axis. This article summarises the physiological regulation of glucagon secretion in humans and considers new findings suggesting that the liver and the gut play key roles in determining fasting and postabsorptive circulating glucagon levels.