OBJECTIVEComprehensive proteomic profiling of the human adipocyte secretome identified dipeptidyl peptidase 4 (DPP4) as a novel adipokine. This study assessed the functional implications of the adipokine DPP4 and its association to the metabolic syndrome.RESEARCH DESIGN AND METHODSHuman adipocytes and skeletal and smooth muscle cells were used to monitor DPP4 release and assess the effects of soluble DPP4 on insulin signaling. In lean and obese subjects, depot-specific expression of DPP4 and its release from adipose tissue explants were determined and correlated to parameters of the metabolic syndrome.RESULTSFully differentiated adipocytes exhibit a substantially higher release of DPP4 compared with preadipocytes or macrophages. Direct addition of DPP4 to fat and skeletal and smooth muscle cells impairs insulin signaling. A fivefold higher level of DPP4 protein expression was seen in visceral compared with subcutaneous fat of obese patients, with no regional difference in lean subjects. DPP4 serum concentrations significantly correlated with adipocyte size. By using adipose tissue explants from lean and obese subjects, we observed a twofold increase in DPP4 release that strongly correlated with adipocyte volume and parameters of the metabolic syndrome and was decreased to the lean level after weight reduction. DPP4 released from adipose tissue correlated positively with an increasing risk score for the metabolic syndrome.CONCLUSIONSDPP4 is a novel adipokine that may impair insulin sensitivity in an autocrine and paracrine fashion. Furthermore, DPP4 release strongly correlates with adipocyte size, potentially representing an important source of DPP4 in obesity. Therefore, we suggest that DPP4 may be involved in linking adipose tissue and the metabolic syndrome.

AimsTo investigate the pharmacodynamics, efficacy and safety of empagliflozin as adjunct to insulin in patients with type 1 diabetes.MethodsA total of 75 patients with glycated haemoglobin (HbA1c) concentrations of ≥7.5 to ≤10.5% (≥58 to ≤91 mmol/mol) were randomized to receive once‐daily empagliflozin 2.5 mg, empagliflozin 10 mg, empagliflozin 25 mg, or placebo as adjunct to insulin for 28 days. Insulin dose was to be kept as stable as possible for 7 days then adjusted, at the investigator's discretion, to achieve optimum glycaemic control. The primary exploratory endpoint was change from baseline in 24‐h urinary glucose excretion (UGE) on day 7.ResultsEmpagliflozin significantly increased 24‐h UGE versus placebo on days 7 and 28. On day 28, adjusted mean differences with empagliflozin versus placebo in changes from baseline in: HbA1c were −0.35 to −0.49% (−3.8 to −5.4 mmol/mol; all p < 0.05 vs. placebo); total daily insulin dose −0.07 to −0.09 U/kg (all p<0.05 vs placebo); and weight were −1.5 to −1.9 kg (all p < 0.001 vs. placebo). In the placebo, empagliflozin 2.5, 10 and 25 mg groups, respectively, adverse events were reported in 94.7, 89.5, 78.9 and 100.0% of patients, and the rate of symptomatic hypoglycaemic episodes with glucose ≤3.0 mmol/l not requiring assistance was 1.0, 0.4, 0.5 and 0.8 episodes per 30 days.ConclusionsIn patients with type 1 diabetes, empagliflozin for 28 days as adjunct to insulin increased UGE, improved HbA1c and reduced weight with lower insulin doses compared with placebo and without increasing hypoglycaemia.

Adipose tissue is a major endocrine organ, releasing signaling and mediator proteins, termed adipokines, via which adipose tissue communicates with other organs. Expansion of adipose tissue in obesity alters adipokine secretion, which may contribute to the development of metabolic diseases. Although recent profiling studies have identified numerous adipokines, the amount of overlap from these studies indicates that the adipokinome is still incompletely characterized. Therefore, we conducted a complementary protein profiling on concentrated conditioned medium derived from primary human adipocytes. SDS-PAGE/liquid chromatography-electrospray ionization tandem MS and two-dimensional SDS-PAGE/matrixassisted laser desorption ionization/time of flight MS identified 347 proteins, 263 of which were predicted to be secreted. Fourty-four proteins were identified as novel adipokines. Furthermore, we validated the regulation and release of selected adipokines in primary human adipocytes and in serum and adipose tissue biopsies from morbidly obese patients and normal-weight controls. Validation experiments conducted for complement factor H, ␣B-crystallin, cartilage intermediate-layer protein, and heme oxygenase-1 show that the release and expression of these factors in adipocytes is regulated by differentiation and stimuli, which affect insulin sensitivity, as well as by obesity. Heme oxygenase-1 especially reveals to be a novel adipokine of interest. In vivo, circulating levels and adipose tissue expression of heme oxygenase-1 are significantly increased in obese subjects compared with lean controls. Collectively, our profiling study of the human adipokinome expands the list of adipokines and further highlights the pivotal role of adipokines in the regulation of multiple biological processes within adipose tissue and their potential dysregulation in obesity. Molecular

AimTo compare day‐to‐day and within‐day variability in glucose‐lowering effect between insulin degludec (IDeg) and insulin glargine 300 U/mL (IGlar‐U300) in type 1 diabetes.Materials and methodsIn this double‐blind, crossover study, patients were randomly assigned to 0.4 U/kg of IDeg or IGlar‐U300 once daily for two treatment periods lasting 12 days each. Pharmacodynamic variables were assessed at steady‐state from the glucose infusion rate profiles of three 24‐hour euglycaemic glucose clamps (days 6, 9 and 12) during each treatment period.ResultsOverall, 57 patients completed both treatment periods (342 clamps). The potency of IGlar‐U300 was 30% lower than IDeg (estimated ratio 0.70, 95% confidence interval [CI] 0.61; 0.80; P < .0001). The distribution of glucose‐lowering effect was stable across 6‐hour intervals (24%‐26%) for IDeg, while IGlar‐U300 had greater effects in the first (35%) and last (28%) intervals compared with 6 to 12 hours (20%) and 12 to 18 hours (17%). Within‐day variability (relative fluctuation) was 37% lower with IDeg than with IGlar‐U300 (estimated ratio IDeg/IGlar‐U300: 0.63, 95% CI 0.54; 0.73; P < .0001). The day‐to‐day variability in glucose‐lowering effect with IDeg was approximately 4 times lower than IGlar‐U300 (variance ratio IGlar‐U300/IDeg: 3.70, 95% CI 2.42; 5.67; P < .0001). The day‐to‐day variability in glucose‐lowering effect assessed in 2‐hour intervals was consistently low with IDeg over 24 hours, but steadily increased with IGlar‐U300 to a maximum at 10 to 12 hours and 12 to 14 hours after dosing (variance ratios 12.4 and 11.4, respectively).Conclusion IDeg has lower day‐to‐day and within‐day variability than IGlar‐U300 and a more stable glucose‐lowering effect, which might facilitate titration and enable tighter glycaemic control with a reduced risk of hypoglycaemia.

Objective: Pigment epithelium-derived factor (PEDF) is a multifunctional protein with neurotrophic and anti-angiogenic properties. More recently it became evident that PEDF is upregulated in patients with type 2 diabetes and also contributes to insulin resistance in mice. During characterization of the secretome of in vitro differentiated human adipocytes by two-dimensional polyacrylamide gel electrophoresis and matrix-assisted laser desorption/ionization-MS, we found that PEDF is one of the most abundant proteins released by adipocytes. The aim of this study was to investigate the regulation and autocrine function of PEDF in human adipocytes and to determine its paracrine effects on human skeletal muscle cells (hSkMC) and human smooth muscle cells (hSMC). Methods and results: Human primary adipocytes secrete 130 ng ml À1 PEDF over 24 h from 1 million cells, which is extremely high as compared with adiponectin, interleukin-6 (IL-6) or IL-8. This release of PEDF is significantly higher than from other primary cells, such as adipose-tissue located macrophages (50-times), hSkMC and hSMC (5-times). PEDF protein expression significantly increases during adipogenesis, which is paralleled by increased PEDF secretion. Furthermore, tumor necrosis factor-a and hypoxia significantly downregulate PEDF protein levels. PEDF secretion was significantly reduced by troglitazone and hypoxia and significantly increased by insulin. Treatment of adipocytes and hSkMC with PEDF induced insulin resistance in adipocytes, skeletal and smooth muscle cells at the level of insulin-stimulated Akt phosphorylation, which was dose dependent and more prominent in adipocytes. Furthermore, inflammatory nuclear factor-kB (NF-kB) signaling was induced by PEDF. In hSMC, PEDF induced proliferation (1.7-fold) and acutely activated proliferative and inflammatory signaling pathways (NF-kB, p38 mitogen-activated protein kinase and mammalian target of rapamycin). Conclusion: PEDF is one of the most abundant adipokines and its secretion is inversely regulated by insulin and hypoxia. PEDF induces insulin resistance in adipocytes and hSkMC and leads to inflammatory signaling in hSMC. Because of these diverse actions, PEDF is a key adipokine, which could have an important role in diabetes and obesity-related disorders.