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Proinsulin (PI) processing is altered in beta-cells during T2D progression. However, the molecular mechanisms driving such alterations are not fully characterized neither their occurrence were correlated with patients’ metabolic profile. To fill this gap, we investigated the correlation between pancreatic proinsulin (PI) expression and phenotypic/functional changes of beta-cells during metabolic stress in extensively clinical characterized impaired glucose tolerant (IGT, n=7) and T2D (n=4) individuals, compared to normal glucose tolerant (NGT, n=4). We analyzed microdissected pancreatic islets collected from surgical pancreas biopsies. The expression of genes associated to ER stress and β cell phenotype were evaluated. Given the high heterogeneity among pancreatic islets, we also performed a single islets analysis in n=88 islets from n=3 NGT, n=3 IGT and n=3 T2D patients. PDIA1, GRP78 and XBP1 genes, involved in unfolded protein response (UPR), were significantly upregulated in pancreatic islets of IGT and T2D patients vs. NGT (p Disclosure N. Brusco: None. C. Cefalo: None. U. Capece: None. F. Impronta: None. A. Mari: Research Support; Self; Eli Lilly and Company. F. Dotta: None. A. Giaccari: None. T. Mezza: None. G. Sebastiani: None. G. Licata: None. G. E. Grieco: None. G. Di giuseppe: None. L. Nigi: None. D. Fignani: None. S. Moffa: None. F. Cinti: None. Funding Università Cattolica del Sacro Cuore (FondiAteneo Linea D.1, anno 2020); Italian Ministry of Education, University and Research (GR-2018-12365577); European Foundation for the Study of Diabetes; AstraZeneca

Sotagliflozin is a dual sodium–glucose co-transporter-2 and 1 (SGLT2/1) inhibitor for the treatment of both type 1 (T1D) and type 2 diabetes (T2D). Sotagliflozin inhibits renal sodium–glucose co-transporter 2 (determining significant excretion of glucose in the urine, in the same way as other, already available SGLT-2 selective inhibitors) and intestinal SGLT-1, delaying glucose absorption and therefore reducing post prandial glucose. Well-designed clinical trials, have shown that sotagliflozin (as monotherapy or add-on therapy to other anti-hyperglycemic agents) improves glycated hemoglobin in adults with T2D, with beneficial effects on bodyweight and blood pressure. Similar results have been obtained in adults with T1D treated with either continuous subcutaneous insulin infusion or multiple daily insulin injections, even after insulin optimization. A still ongoing phase 3 study is currently evaluating the effect of sotagliflozin on cardiovascular outcomes (ClinicalTrials.gov NCT03315143). In this review we illustrate the advantages and disadvantages of dual SGLT 2/1 inhibition, in order to better characterize and investigate its mechanisms of action and potentialities.

Aims/hypothesis Type 2 diabetes (T2D) is characterized by a progressive loss of beta-cell function, and the “disappearance” of beta-cells in T2D may also be caused by the process of beta -cell dedifferentiation. Since noradrenergic innervation inhibits insulin secretion and density of noradrenergic fibers is increased in type 2 diabetes mouse models, we aimed to study the relation between islet innervation, dedifferentiation and beta-cell function in humans. Methods Using immunohistochemistry and electron microscopy, we analyzed pancreata from organ donors and from patients undergoing pancreatic surgery. In the latter, a pre-surgical detailed metabolic characterization by oral glucose tolerance test (OGTT) and hyperglycemic clamp was performed before surgery, thus obtaining in vivo functional parameters of beta-cell function and insulin secretion. Results The islets of diabetic subjects were 3 times more innervated than controls (0.91 ± 0.21 vs 0.32 ± 0.10, n.fibers/islet; p = 0.01), and directly correlated with the dedifferentiation score (r = 0.39; p = 0.03). In vivo functional parameters of insulin secretion, assessed by hyperglycemic clamp, negatively correlated with the increase in fibers [beta-cell Glucose Sensitivity (r = −0.84; p = 0.01), incremental second-phase insulin secretion (r = −0.84, p = 0.03) and arginine-stimulated insulin secretion (r = −0.76, p = 0.04)]. Moreover, we observed a progressive increase in fibers, paralleling worsening glucose tolerance (from NGT through IGT to T2D). Conclusions/interpretation Noradrenergic fibers are significantly increased in the islets of diabetic subjects and this positively correlates with beta-cell dedifferentiation score. The correlation between in vivo insulin secretion parameters and the density of pancreatic noradrenergic fibers suggests a significant involvement of these fibers in the pathogenesis of the disease, and indirectly, in the islet dedifferentiation process.

BACKGROUNDThe appearance of hyperglycemia is due to insulin resistance, functional deficits in the secretion of insulin, and a reduction of β cell mass. There is a long-standing debate as to the relative contribution of these factors to clinically manifesting β cell dysfunction. The aim of this study was to verify the acute effect of one of these factors, the reduction of β cell mass, on the subsequent development of hyperglycemia.METHODSTo pursue this aim, nondiabetic patients, scheduled for identical pancreaticoduodenectomy surgery, underwent oral glucose tolerance tests (OGTT) and hyperglycemic clamp (HC) procedures, followed by arginine stimulation before and after surgery. Based on postsurgery OGTT, subjects were divided into 3 groups depending on glucose tolerance: normal glucose tolerance (post-NGT), impaired glucose tolerance (post-IGT), or having diabetes mellitus (post-DM).RESULTSAt baseline, the 3 groups showed similar fasting glucose and insulin levels; however, examining the various parameters, we found that reduced first-phase insulin secretion, reduced glucose sensitivity, and rate sensitivity were predictors of eventual postsurgery development of IGT and diabetes.CONCLUSIONDespite comparable functional mass and fasting glucose and insulin levels at baseline and the very same 50% mass reduction, only reduced first-phase insulin secretion and glucose sensitivity predicted the appearance of hyperglycemia. These functional alterations could be pivotal to the pathogenesis of type 2 diabetes (T2DM).TRIAL REGISTRATIONClinicalTrials.gov NCT02175459.FUNDINGUniversita Cattolica del Sacro Cuore; Italian Ministry of Education, University and Research; European Foundation for the Study of Diabetes.

Increased circulating levels of proinsulin (PI) and proinsulin-to-insulin ratio (PI/INS) is a well-known abnormality in type 2 diabetes (T2D). The exact mechanism behind this increase in T2D, as well as in T1D, is unknown. The aim of this study was to analyze proinsulin and insulin expression in pancreatic islets of tissue biopsies of patients undergoing partial pancreatectomy (PP) with normal glucose tolerance (NGT), impaired glucose tolerance (IGT) and T2D, in order to explore the alterations that occur in islets during metabolic stress. Frozen sections of pancreatic tissue biopsies (n=17) classified following OGTT into n=5 NGT, n=9 IGT and n=3 T2D were stained for INS and PI through double immunofluorescence staining. β-cell glucose sensitivity (calculated as the ratio of insulin secretion and glucose increments), basal insulin secretion, and glucose levels 2-hours following OGTT were analyzed. Image analysis was performed on each individual islet through Volocity software. In-situ staining measurements were correlated with patients’ clinical parameters. PI-INS colocalization as well as the area (µm2) of PI positivity and PI/INS ratio gradually increased from NGT to IGT and T2D pancreatic islets (p In conclusion, our results suggest that the increase of PI/INS ratio in pancreatic islets is directly related to metabolic defects in dysfunctional β cells, highlighting the importance of correct PI processing and folding in the maintenance of glucose homeostasis. Disclosure N. Brusco: None. G. Sebastiani: None. G. Licata: None. G.E. Grieco: None. L. Nigi: None. D. Fignani: None. S. Moffa: None. G. Sorice: None. G. Di Giuseppe: None. C. Cefalo: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. F. Dotta: None. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis. T. Mezza: None. Funding European Foundation for the Study of Diabetes; AstraZeneca

Insulin resistance and β-cell dysfunction are the main actors in the pathogenesis of type 2 diabetes mellitus, causing both quantitative and qualitative loss of insulin secretion and therefore hyperglycemia. The molecular mechanisms underlying progressive β-cell dysfunction, however, are still unknown. In order to correlate changes in the insular proteome to different metabolic conditions in vivo, a mass spectrometry analysis was performed on human islets, extracted by Laser Capture Microdissection, from surgical samples of 14 subjects who underwent duodeno-cephalopancreasectomy, and previously studied through OGTT and mixed meal test. The subjects were classified based on glucose tolerance into normal (n: 7 NGT), intolerant (n: 5 IGT) and diabetic (n: 2 DM2). A first quantitative analysis showed about 150 proteins differently expressed in the 3 groups. Among these, a protein, SEL1L, which regulates the differentiation of pancreatic precursors in the endocrine line was significantly increased in IGT rather than DM2 and NGT subjects and was inversely correlated with β-cell glucose sensitivity (r = -0.81, p = 0.01). The TCPD protein, involved in the folding and transport of neosynthesized proteins, which progressively decreases from NGT to DM2, was inversely correlated with the AUC of glycemia during OGTT (r = 0.5, p = 0.04). Finally, the expression of IQAG1 which was significantly reduced in DM2 compared to the other groups, and implicated in GLP-1 induced insulin production was inversely correlated with insulin resistance evaluated using the HOMA-IR index (r = -0.70, p = 0.004). The results suggest that both insulin resistance and/or β-cell dysfunction in vivo are closely linked to the intrainsular proteome in diabetic subjects. Disclosure C. Cefalo: None. T. Mezza: None. F. Cinti: None. S. Moffa: None. U. Capece: None. R. Kulkarni: None. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis.

PCSK9 inhibitors are monoclonal antibodies effective in reducing LDL-C and cardiovascular events by neutralizing circulating PCSK9. Since PCSK9 is also expressed in other organs, including pancreas, studies on PCSK9 KO mice, have shown impaired insulin secretion. Other murine models in which PCSK9 was silenced only in the liver (mimicking the action of PCSK9i) had normal glucose metabolism. The aim of our study was to evaluate the effect of PCSK9 inhibitors on glucose metabolism and beta cell function in humans. 11 nondiabetic subjects candidate for PCSK9i therapy were enrolled in the study. All subjects underwent an OGTT at baseline and after 6 months of therapy, at which point surrogate insulin sensitivity indices were obtained (Matsuda; OGIS). During OGTT, insulin secretion parameters were derived from C-peptide levels by deconvolution; we evaluated basal insulin secretion rate, total insulin secretion rate and β-cell glucose sensitivity, for 6 of the 11 enrolled subjects. All patients showed a 53.3% reduction in LDL cholesterol after 6 months of therapy; the mean LDL-C baseline level (B) was 202.5 ± 45 mg/dl, while mean LDL-C post therapy (PT) value was 94.6 ± 27 mg/dl. Glycemic and insulinemic curves showed no significant differences between baseline and follow-up. Matsuda index (B 4.1 ± 1, PT 3.4 ± 0.7 mL min-1kg-1) and OGIS (B 396.9 ± 32, PT 386.2 ± 28 ml min-1m-2), showed no differences between baseline and post-therapy evaluation. There were no significant differences in insulin secretion parameters: basal insulin secretion rate (B 63.7 ± 34, PT 66.4 ± 23 pmol min-1m-2), total insulin secretion rate (B 48.7 ± 17, PT 46.9 ± 16, nmol m-2) and β-cell glucose sensitivity (B 117.5 ± 69, PT 141.2 ± 47 pmol min-1m-2mM-1) obtained from c-peptide deconvolution. Our study, although preliminary and in a small sample of patients, suggests that PCSK9is does not cause alterations in glucose metabolism and beta cell function. Further studies and a longer follow-up may provide us with further data to confirm our observations. Disclosure S. Moffa: None. T. Mezza: None. C. Cefalo: None. F. Cinti: None. G. Sorice: None. F. Impronta: None. U. Capece: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis.

β-cell functional defects temporally anticipate (and eventually cause) the subsequent development of hyperglycemia, whereas a significant reduction (∼50%) of beta-cell mass is observed at diagnosis of T2D. To further investigate the relative role of beta-cell mass reduction/dysfunction in the development of T2D, we performed, pre- and post-surgery, oral glucose tolerance tests (OGTT) and hyperglycemic clamps (HC), followed by arginine stimulation and mixed meal test (MMT), in 39 patients undergoing pancreatoduodenectomy (PD), as model of acute mass reduction. Based on post-surgery OGTT, subjects were divided into 3 groups depending on glucose tolerance: normal (NGT, n=11), impaired (IGT, n=10) or diabetic (DM, n=18) (23 F/16 M, 63±13.7 yrs, BMI 23.9±4.5 kg/m2). To evaluate β-cell function, β-cell glucose sensitivity (GS) was calculated during HC, MMT e OGTT as the ratio of insulin secretion (IS) and glucose increments. Comparison among the 3 groups revealed that PD had a significantly different effect on time-dependent change of glucose and insulin levels during all tests (P Disclosure T. Mezza: None. P. Ferraro: None. G. Di Giuseppe: None. C. Cefalo: None. S. Moffa: None. G. Quero: None. F. Cinti: None. F. Impronta: None. U. Capece: None. S. Alfieri: None. A. Mari: Consultant; Self; Lilly Diabetes. Research Support; Self; Boehringer Ingelheim International GmbH. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis.

β dedifferentiation is recognized as one of the main mechanisms responsible for the disappearance of β cells from pancreatic islets of diabetic subjects, but the underlying process is still unclear. Noradrenergic innervation is known to inhibit insulin secretion, and in pancreas of diabetic subjects a 3-fold increase of noradrenergic fibers was observed compared to nondiabetic subjects, directly related to the % of dedifferentiated cells within the islets. The increase in fibers has been associated with worsening β cell function, suggesting a role in the pathogenesis of the disease and perhaps in the process of dedifferentiation. The aim of our study was to use in vitro human β cell models to explore a direct role of innervation in the process of noradrenergic dedifferentiation. The human β cell line EndoC-βH1 was exposed to different concentrations of noradrenaline (NA) (0.4 μM, 4 μM and 40 μM) for 24 and 72 h. The expression of β cell dedifferentiation markers was assessed before and after stimulation of the α2A adrenergic receptor, by morphology (immunofluorescence (IF)), qPCR and ELISA. FGF2 (100 ng/mL), a known inducer of β dedifferentiation in vitro, was used as a positive control. NA treatment did not have any impact on β cell viability, while, as expected, it slightly reduced insulin secretion after 24 h. The expression of β cell dedifferentiation markers (ALDH1a3) was increased by approximately 30% after stimulation with NA, while mature β cell marker were reduced (NKX6.1) up to 60% after 72 h (by IF detection). Moreover, the mRNA expression of FOXO1, the main transcription factor involved in the dedifferentiation process, was reduced up to 35.4% after 72 h stimulation with NA. We observed a dose and time dependent pattern in all the experiments. In conclusion, the data suggest a direct role of noradrenergic fibers in the dedifferentiation process, potentially identifying a new target for the prevention and therapy of type 2 diabetes. Disclosure F. Cinti: None. F. Fantuzzi: None. A. Carfí: None. T. Mezza: None. C. Cefalo: None. S. Moffa: None. G. Sorice: None. A. Giaccari: Speaker’s Bureau; Self; Amgen, AstraZeneca, Eli Lilly and Company, Merck Sharp & Dohme Corp., Mundipharma, Novo Nordisk A/S, Sanofi-Aventis. M. Cnop: None. Funding European Foundation for the Study of Diabetes

The study investigated the diagnostic performance for diabetic cardiovascular autonomic neuropathy (CAN) and diabetic polyneuropathy (DPN) of the combined use of composite autonomic symptom score (COMPASS) 31, validated questionnaire for autonomic symptoms of CAN, and electrochemical skin conductance (ESC), proposed for detecting DPN and CAN. One-hundred and two participants with diabetes (age 57 ± 14 years, duration 17 ± 13 years) completed the COMPASS 31 before assessing cardiovascular reflex tests (CARTs), neuropathic symptoms, signs, vibratory perception threshold (VPT), thermal thresholds (TT), and ESC using Sudoscan. Two patterns were evaluated: (a) the combined abnormalities in both tests (COMPASS 31+ESC), and (b) the abnormality in COMPASS 31 and/or ESC (COMPASS 31 and/or ESC). CAN (≥1 abnormal CART) and confirmed CAN (≥2 abnormal CARTs) were present in 28.1% and 12.5%, DPN (two abnormalities among symptoms, signs, VPT, and TT) in 52%, abnormal COMPASS 31 (total weighted score >16.44) in 48% and abnormal ESC (hands ESC

Although it is well established that diabetes can also develop as a result of diseases or maneuvers on the exocrine pancreas, the complex relationship between glucose disorders and underlying pancreatic disease is still debated. There is evidence that several features linked to pancreatic diseases can modify endocrine and metabolic conditions before and after surgery. However, pancreatic surgery provides a rare opportunity to correlate in vivo endocrine and metabolic pathways with ex vivo pancreatic samples, to examine the endocrine and metabolic effects of acute islet removal, and finally to clarify the pathogenesis of diabetes. This approach could therefore represent a unique method to shed light on the molecular mechanisms, predicting factors, and metabolic consequences of insulin resistance, islet plasticity, 13 cell failure, and type 2 diabetes.

Increased proinsulin secretion, which characterizes type 2 diabetes and insulin resistance, may be due to an intrinsic, primitive defect in proinsulin processing or be secondary to increased demand on β-cells (hyperinsulinemia secondary to insulin resistance). An alternative way to investigate the relation between relative hyperproinsulinemia and increased secretory demand is to study the dynamic changes in the proinsulin-to-insulin ratio after partial pancreatectomy, a model of acute increased β-cell workload on the remaining pancreas. To pursue this aim, patients without diabetes, scheduled for partial pancreatectomy, underwent 4-h mixed-meal tests and hyperinsulinemic-euglycemic clamps before and after surgery. After acute β-cell mass reduction, no changes were observed in the fasting proinsulin-to-insulin ratio, whereas the fold change in the proinsulin-to-insulin ratio significantly increased over time after the meal. Further, our data demonstrate that whole-body insulin resistance is associated with underlying defects in proinsulin secretion, which become detectable only in the presence of increased insulin secretion demand.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are the latest therapeutic strategy in the treatment of type 2 diabetes mellitus (T2DM). Using an insulin-independent mechanism (glycosuria), they reduce glucose toxicity and improve insulin sensitivity and β-cell function. The promising results obtained in clinical trials show that SGLT2 significantly improves glycemic control and provides greater cardiovascular protection, combined with a reduction in body weight and blood pressure (BP). This review focuses on ertugliflozin, a new, highly selective, and reversible SGLT2 inhibitor. Clinical trials published to date show that ertugliflozin, both as a monotherapy and as an add-on to oral antidiabetic agents, is safe and effective in reducing glycosylated hemoglobin (HbA1c), body weight, and BP in T2DM patients.

Several evidences suggest that the functional β cell defects anticipate the onset of hyperglycemia and the reduction of mass. To assess whether the β-cell deterioration corresponds to a loss of β-cell mass, we performed glucose oral tolerance test (OGTT) and hyperglycemic clamp (HC) followed by arginine stimulation, in 16 nondiabetic patients who underwent pancreatoduodenectomy (PD), pre and post-surgery. Based on the post-operative OGTT, the subjects were divided into 3 glucose tolerance groups: normal (NGT, n = 5), altered (IGT, n = 4) or diabetes (DM, n = 7) (8F/8M, 51 ± 15 years). To evaluate β cell function, βcell glucose sensitivity (GS) was calculated during HC, as a ratio between insulin secretion and glucose increase. On surgical pancreas samples, the% of intraparenchymal white adipose tissue (WATi score) was measured. Before surgery, insulin secretion after arginine (AIS) was similar between groups, while GS was lower in IGT and DM compared to NGT subjects (62.9 ± 23.1 and 45.5 ± 11.2 vs. 90.6 ± 18.7 pmol • min-1 • m-2, respectively). After 50% PD, the GS decreased in all patients (p Disclosure F. Cinti: None. T. Mezza: None. C. Cefalo: None. G. Sorice: None. S. Moffa: None. I. Severi: None. S. Cinti: None. A. Giaccari: Advisory Panel; Self; Sanofi. Board Member; Self; Novo Nordisk A/S. Speaker's Bureau; Self; Amgen Inc., AstraZeneca, Merck Sharp & Dohme Corp., Sanofi.

Recent studies in mouse models showed that Liraglutide can modulate gut microbiota suggesting this as one of the factors favoring the drug-induced weight loss. We here aimed to observationally evaluate the effect of Liraglutide on gut microbiota composition in obese diabetic humans. 11 obese diabetic subjects (age 59.6 ± 9.8; HbA1C 7.7 ± 2.7%; weight: 95.5 ± 17 kg), candidates to receive GLP-1-analogs, were included. All subjects underwent, before (B) and after 6 weeks of treatment (PT) with Liraglutide 1.2 mg, metabolic evaluation (BMI, glucose, HbA1c and LDL-cholesterol). Lactulose Breath Test (LBT) was performed to characterize gut microbiota, measuring hydrogen (H2) and methane (CH4) production; while gastric emptying time (t/2) was assessed by Octanoic Acid Breath Test. All subjects experienced a significant weight loss (BMI B: 33.9 ± 4.5 kg/m2, PT: 29.9 ± 4.2 kg/m2, p 0,001), and a significant reduction of fasting plasma glucose (FPG) (FPG B: 146.4 ± 31.5 mg/dl, PT: 118.6 ± 33.1 mg/dl p 0.02), Hb1Ac (HbA1C B: 7.7 ± 2.7%, PT: 6.2 ± 1% p 0.001) and LDL-cholesterol (LDL B: 89.5 ± 39.3 mg/dl; PT: 68.4 ± 35.9 mg/dl, p 0.006). Methane and Hydrogen production (AUC) were significantly reduced by Liraglutide in the post-treatment group (H2 B: 5093.8 ± 933 ppm, PT: 2495.5 ± 525 ppm, p 0.02; CH4 B: 1887.9 ± 286.3, PT: 1212.3 ± 334 ppm, p 0.02); moreover, the LBT revealed that Liraglutide is able to significantly slow down the Oro-cecal Transit Time (OTT). As expected, gastric emptying was significantly delayed after Liraglutide treatment (t/2 B: 72.6 ± 8.2 min, PT: 118.2 ± 25 min p 0.05). We, here, show that Liraglutide reduces intestinal gases production, which is an indirect measure of changes in gut microbiota. In conclusion, we highlight the close relationship between glucose lowering effect of Liraglutide and the intestinal microbiota composition, suggesting that the treatment effect may be potentially mediated by changes in gut microbiota, which could in turn represent a new therapeutic target for treatment of type 2 diabetes. Disclosure S. Moffa: None. V. Tesori: None. T. Mezza: None. C. Cefalo: None. F. Cinti: None. G. Sorice: None. A. Giaccari: Advisory Panel; Self; Sanofi. Board Member; Self; Novo Nordisk A/S. Speaker's Bureau; Self; Amgen Inc., AstraZeneca, Merck Sharp & Dohme Corp., Sanofi.

Objective Changes in bile flow after bariatric surgery may beneficially modulate secretion of insulin and incretins, leading to diabetes remission. However, the exact mechanism(s) involved is still unclear. Here, we propose an alternative method to investigate the relationship between alterations in physiological bile flow and insulin and incretin secretion by studying changes in gut-pancreatic function in extrahepatic cholestasis in nondiabetic humans. Methods To pursue this aim, 58 nondiabetic patients with recent diagnosis of periampullary tumors underwent an oral glucose tolerance test (OGTT), and a subgroup of 16 patients also underwent 4-hour mixed meal tests and hyperinsulinemic-euglycemic clamps. Results The analysis of the entire cohort revealed a strong inverse correlation between total bilirubin levels and insulinogenic index. When subjects were divided on the basis of bilirubin levels, used as a marker of altered bile flow, subjects with high bilirubin levels displayed inferior glucose control and decreased insulin secretion during the OGTT. Altered bile flow elicited a markedly greater increase in glucagon and glucagon-like peptide 1 (GLP-1) secretion at fasting state, and following the meal, both glucagon and GLP-1 levels remained increased over time. Conversely, Glucose-dependent insulinotropic polypeptide (GIP) levels were comparable at the fasting state, whereas the increase following meal ingestion was significantly blunted with high bilirubin levels. We reveal strong correlations between total bilirubin and glucagon and GLP-1 levels. Conclusions Our findings suggest that acute extrahepatic cholestasis determines major impairment in enteroendocrine gut-pancreatic secretory function. The altered bile flow may determine a direct deleterious effect on β-cell function, perhaps mediated by the impairment of incretin hormone function.

Although it is well established that type 2 diabetes (T2D) is generally due to the progressive loss of β-cell insulin secretion against a background of insulin resistance, the actual correlation of reduced β-cell mass to its defective function continues to be debated. There is evidence that a compensatory increase in β-cell mass, and the consequent insulin secretion, can effectively cope with states of insulin resistance, until hyperglycemia supervenes. Recent data strongly indicate that the mechanisms by which islets are able to compensate in response to insulin resistance in peripheral tissues is secondary to hyperplasia, as well as the activation of multiple cellular machineries with diverse functions. Importantly, islet cells exhibit plasticity in altering their endocrine commitment; for example, by switching from secretion of glucagon to secretion of insulin and back (transdifferentiation) or from an active secretory state to a nonsecretory quiescent state (dedifferentiation) and back. Lineage tracing (a method used to track each cell though its differentiation process) has demonstrated these potentials in murine models. A limitation to drawing conclusions from human islet research is that most studies are derived from human autopsy and/or organ donor samples, which lack in vivo functional and metabolic profiling. In this review, we specifically focus on evidence of islet plasticity in humans—from the normal state, progressing to insulin resistance to overt T2D—to explain the seemingly contradictory results from different cross-sectional studies in the literature. We hope the discussion on this intriguing scenario will provide a forum for the scientific community to better understand the disease and in the long term pave the way for personalized therapies.

Diabetes is not a single and homogeneous disease, but a cluster of metabolic diseases characterized by the common feature of hyperglycemia. The pathogenesis of type 1 diabetes (T1D) and type 2 diabetes (T2D) (and all other intermediate forms of diabetes) involves the immune system, in terms of inflammation and autoimmunity. The past decades have seen an increase in all types of diabetes, accompanied by changes in eating habits and consequently a structural evolution of gut microbiota. It is likely that all these events could be related and that gut microbiota alterations might be involved in the immunomodulation of diabetes. Thus, gut microbiota seems to have a direct, even causative role in mediating connections between the environment, food intake, and chronic disease. As many conditions that increase the risk of diabetes modulate gut microbiota composition, it is likely that immune-mediated reactions, induced by alterations in the composition of the microbiota, can act as facilitators for the onset of diabetes in predisposed subjects. In this review, we summarize recent evidence in the field of gut microbiota and the role of the latter in modulating the immune reactions involved in the pathogenesis of diabetes.

The pathogenesis of type 2 diabetes is characterized by a progressive β-cell dysfunction resulting in both quantitative and qualitative loss of insulin secretion. However, the molecular mechanisms underlying this progressive functional loss are still unknown. The aim of the study is to highlight changes in the proteome of pancreatic human islets that can anticipate and eventually predict diabetes’ onset. High performance liquid chromatography mass spectrometry (HPLC-MS) analysis was applied to islets isolated by laser capture microdissection (LCM) from human samples of both diabetic and no diabetic subjects, underwent to duodeno-cefalopancreatectomy for extra-pancreatic, low grading tumors. The subjects were classified on the basis of glucose tolerance assessed by an OGTT before surgery in normal tolerant (NGT, n:7), glucose intolerant (IGT, n:5) and diabetic subjects (T2DM, n:2). Qualitative and quantitative analysis were performed to detect differential protein expression among the 3 study’s groups. Sixty-seven proteins were found to be differentially regulated in diabetic subjects compare to NGT, with 29 upregulated and 38 downregulated proteins, while 95 proteins were differentially expressed in IGT compare to NGT with 49 upregulated and 46 downregulated. These proteins are mainly involved in cellular and metabolic processes. In particular IGT and DM, compared to NGT, showed a lower expression of proteins involved in cell proliferation such as PURA and NAP1L1, as well as proteins involved in the insulin cleavage process, like ERO1B. While other proteins involved in endoplasmic reticulum stress, CASP14, ERP27 and PDIA3, resulted upregulated in both IGT and DM compare to NGT. Our data suggest that metabolic and cellular processes of islet cells are already dysregulated in patients with impaired glucose tolerance, highlighting some proteins as potential early markers of β-cell dysfunction and novel therapeutic targets to slow the progression to type 2 diabetes. Disclosure C. Cefalo: None. T. Mezza: None. R. Kulkarni: None. A. Giaccari: Advisory Panel; Self; Sanofi-Aventis. Speaker's Bureau; Self; AstraZeneca, Merck Sharp & Dohme Corp., Amgen Inc..

Nondiabetic insulin-resistant subjects (InsRes) display an increased α-cell mass, suggesting a key role of α-cells in the compensatory mechanisms to cope with insulin resistance states. The mechanism contributing to greater GLP-1 secretion detected in healthy patients following pancreatoduodenectomy (PD), is not fully understood and suggests other potential sources of the incretin hormone, such as α-cells. To investigate the dynamic changes of in-vivo GLP-1 secretion, insulin secretion (IS), and incretin effect (IE), 16 nondiabetic patients (10 F/6 M, 51±15 years.) scheduled for PD underwent a mixed meal test (MMT), a 2-h hyperglycemic clamp (HC), and a hyperinsulinemic euglycemic clamp (HEC) before and after surgery. β-cell glucose sensitivity (GS) was calculated as the ratio of IS and glucose increments, both during HC and MMT. The IE was estimated as the ratio of GS during the HC and MMT. InsRes displayed a reduction in the 1st IS at baseline (p=0.04), which did not decrease following PD. Both groups experienced a reduction of 2nd phase ISR (p Disclosure T. Mezza: None. S. Moffa: None. G. Sorice: None. C. Cefalo: None. F. Cinti: None. A. Mari: None. A. Giaccari: Advisory Panel; Self; Sanofi-Aventis. Speaker's Bureau; Self; AstraZeneca, Merck Sharp & Dohme Corp., Amgen Inc..

Objective The aim was to investigate whether vitamin D supplementation, combined with a hypocaloric diet, could have an independent effect on insulin sensitivity in subjects with both overweight and hypovitaminosis D. Changes from baseline in anthropometric parameters, body composition, glucose tolerance, and insulin secretion were considered as secondary outcomes. Methods Eighteen volunteers who were nondiabetic and vitamin D deficient and had BMI > 25 kg/m2 were randomized (1:1) in a double-blind manner to a hypocaloric diet + either oral cholecalciferol at 25,000 IU/wk or placebo for 3 months. Hyperinsulinemic-euglycemic clamp to measure insulin sensitivity was performed at baseline and after intervention. Results Body weight in both groups decreased significantly (−7.5% in the vitamin D group and −10% in the placebo group; P

CONTEXT: Insulin resistance impacts virtually all tissues, including pancreatic β cells. Individuals with insulin resistance, but without diabetes, exhibit an increased islet size because of an elevated number of both β and α cells. Neogenesis from duct cells and transdifferentiation of α cells have been postulated to contribute to the β-cell compensatory response to insulin resistance. OBJECTIVE: Our objective was to explore parameters that could potentially predict altered islet morphology. METHODS: We investigated 16 nondiabetic subjects by a 2-hour hyperglycemic clamp to evaluate β-cell secretory function. We analyzed pancreas samples obtained during pancreatoduodenectomy in the same patients to examine glucagon and insulin double+ cells to assess islet morphology. RESULTS: Among all the functional in vivo parameters of insulin secretion that were explored (basal, first phase and total secretion, glucose sensitivity, arginine-stimulated insulin secretion), β-cell glucose sensitivity was unique in exhibiting a significant correlation with both islet size and α-β double+ islet cells. CONCLUSIONS: Our data suggest that poor β-cell glucose sensitivity is linked to islet transdifferentiation, possibly from α cells to β cells, in an attempt to cope with higher demands for insulin secretion. Understanding the mechanism(s) that underlies the adaptive response of the islet cells to insulin resistance is a potential approach to design tools to enhance functional β-cell mass for diabetes therapy.

Background Pancreaticoduodenectomy represents the major treatment for pancreatic and periampullary neoplasms. Complications related to pancreaticojejunostomy are still the leading cause of morbidity and mortality. A solution proposed by some surgeons is the occlusion of main pancreatic duct by acrylic glue, avoiding pancreaticojejunostomy. Nevertheless, the consequences of this procedure on glucose metabolism are not well-defined. Methods We retrospectively analyzed a cohort of 50 patients who underwent pancreaticoduodenectomy and had metabolic assessments available. The metabolic evaluation included the following: body composition and clinical evaluation, an oral glucose tolerance test, and an hyperinsulinemic euglycemic clamp procedure. Results Twenty-three patients underwent pancreatic duct occlusion and were compared with 27 patients, well-matched controls, who underwent pancreaticojejunostomy. Pancreatic duct occlusion leads to a greater impairment in insulin secretion compared with classic pancreaticojeunostomy. Conclusion Pancreatic duct occlusion is associated with a greater reduction in insulin secretion but does not lead to meaningful differences in the management of patients with diabetes.