Growth Hormone, Atherosclerosis and Peripheral Arterial Disease: Exploring the Spectrum from Acromegaly to Growth Hormone Deficiency.

Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) are increasingly recognised for their role in cardiovascular (CV) physiology. The GH-IGF-1 axis plays an essential role in the development of the CV system as well as in the complex molecular network that regulates cardiac and endothelial structure and function. A considerable correlation between GH levels and CV mortality exists even among individuals in the general population without a notable deviation in the GHIGF- 1 axis functioning. In addition, over the last decades, evidence has demonstrated that pathologic conditions involving the GH-IGF-1 axis, as seen in GH excess to GH deficiency, are associated with an increased risk for CV morbidity and mortality. A significant part of that risk can be attributed to several accompanying comorbidities. In both conditions, disease control is associated with a consistent improvement of CV risk factors, reduction of CV mortality, and achievement of standardised mortality ratio similar to that of the general population. Data on the prevalence of peripheral arterial disease in patients with acromegaly or growth hormone deficiency and the effects of GH and IGF-1 levels on the disease progression is limited. In this review, we will consider the pivotal role of the GH-IGF-1 axis on CV system function, as well as the far-reaching consequences that arise when disorders within this axis occur, particularly in relation to the atherosclerosis process.

Efficacy and safety of once-weekly semaglutide 1.0mg vs once-daily liraglutide 1.2mg as add-on to 1-3 oral antidiabetic drugs in subjects with type 2 diabetes (SUSTAIN 10).

AIMS: SUSTAIN 10 compared the efficacy and safety of the anticipated most frequent semaglutide dose (1.0mg) with the current most frequently prescribed liraglutide dose in Europe (1.2mg), reflecting clinical practice. METHODS: In this phase 3b, open-label trial, 577 adults with type 2 diabetes (HbA1c 7.0-11.0%) on 1-3 oral antidiabetic drugs were randomized 1:1 to subcutaneous once-weekly semaglutide 1.0mg or subcutaneous once-daily liraglutide 1.2mg. Primary and confirmatory secondary endpoints were changes in HbA1c and body weight from baseline to week 30, respectively. RESULTS: Mean HbA1c (baseline 8.2%) decreased by 1.7% with semaglutide and 1.0% with liraglutide (estimated treatment difference [ETD] -0.69%; 95% confidence interval [CI] -0.82 to -0.56, P<0.0001). Mean body weight (baseline 96.9kg) decreased by 5.8kg with semaglutide and 1.9kg with liraglutide (ETD -3.83kg; 95% CI -4.57 to -3.09, P<0.0001). The proportions of subjects achieving glycaemic targets of<7.0% and=6.5%, weight loss of=5% and=10%, and a composite endpoint of HbA1c<7.0% without severe or blood glucose-confirmed symptomatic hypoglycaemia and no weight gain were greater with semaglutide vs liraglutide (all P<0.0001). Both treatments had similar safety profiles, except for more frequent gastrointestinal disorders (the most common adverse events [AEs]) and AEs leading to premature treatment discontinuation with semaglutide vs liraglutide (43.9% vs 38.3% and 11.4% vs 6.6%, respectively). CONCLUSION: Semaglutide was superior to liraglutide in reducing HbA1c and body weight. Safety profiles were generally similar, except for higher rates of gastrointestinal AEs with semaglutide vs liraglutide.

Effects of liraglutide on obesity-associated functional hypogonadism in men.

Lifestyle measures (LSMs) should be the first-line approach offered for obesity-related functional hypogonadism (FH). When LSMs fail, the role of testosterone replacement treatment (TRT) is unclear. GLP1 receptor agonist liraglutide is linked to progressive and sustained weight loss. A potential direct impact of GLP1 on hypothalamus-pituitary-testicular (HPT) axis was reported in animal models. We aimed to compare the effects of liraglutide and TRT on FH in obese men that had been poor responders to LSM, by means of reversal of FH and weight reduction. We designed a 16-week prospective randomized open-label study with 30 men (aged 46.5 ± 10.9 years, BMI 41.2 ± 8.4 kg/m2, mean ± s.d.) that were randomized to liraglutide 3.0 mg QD (LIRA) or 50 mg of 1% transdermal gel QD (TRT). Sexual function and anthropometric measures were assessed. Fasting blood was drawn for determination of endocrine and metabolic parameters followed by OGTT. Model-derived parameters including HOMAIR and calculated free testosterone (cFT) were calculated. Total testosterone significantly increased in both arms (+5.9 ± 7.2 in TRT vs +2.6 ± 3.5 nmol/L in LIRA) and led to improved sexual function. LIRA resulted in a significant increase of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) (P < 0.001 for between-treatment effect). Subjects treated with LIRA lost on average 7.9 ± 3.8 kg compared with a 0.9 ± 4.5 kg loss in TRT (P < 0.001). Metabolic syndrome was resolved in two patients in LIRA and in no subjects in TRT. Liraglutide was superior to TRT in improving an overall health benefit in men with obesity-associated FH after LSM failed.

Adiponectin/leptin ratio and insulin resistance in pregnancy.

OBJECTIVE: Pregnancy is characterized by progressive insulin resistance. The present study evaluated whether the adiponectin/leptin ratio is associated with insulin resistance in pregnancy, since this ratio has been shown to be associated with insulin resistance in obesity, type 2 diabetes mellitus, metabolic syndrome and polycystic ovary syndrome. METHODS: In this cross-sectional study, adiponectin and leptin concentrations were measured in pregnant women using enzyme-linked immunosorbent assays. Insulin resistance was assessed using the homeostasis model assessment of insulin resistance (HOMA-IR). RESULTS: Mean ± SD age of the participants (n = 74) was 30.76 ± 4.27 years, mean ± SD gestational age was 26.81 ± 3.52 weeks and median body mass index (BMI) before pregnancy was 22.68 kg/m(2) (interquartile range 20.75-26.79 kg/m(2)). There was a significant correlation between the HOMA-IR and leptin concentration, but not between the HOMA-IR and adiponectin concentration. There was a significant inverse correlation between the HOMA-IR and adiponectin/leptin ratio. The adiponectin/leptin ratio was inversely correlated with BMI before pregnancy. CONCLUSION: The adiponection/leptin ratio inversely correlates with HOMA-IR in pregnancy.

Insulinoma causing liver metastases 15 years after initial surgery, accompanied by glomerulonephritis.

Insulinoma is a rare pancreatic endocrine tumor that is typically sporadic, solitary, and less than 2 cm in diameter. Ninety percent of all insulinomas are benign. Up to 10 percent are malignant and are usually larger in size. We report a case of an unusual, not yet described association of two diseases: a malignant pancreatic insulinoma recurred as a multiple liver metastasis 15 years after the initial complete enucleation of a primary tumor with a histomorphological fairly benign outlook, accompanied by ANCA positive crescentic glomerulonephritis.

Continuous subcutaneous insulin infusion in adult type 1 diabetes mellitus: data from a registry at the University Medical Centre Ljubljana, Slovenia.

OBJECTIVE: To evaluate the treatment indications, effectiveness and adverse events of continuous subcutaneous insulin infusion (CSII) in adults with type 1 diabetes mellitus using data from a registry at the University Medical Centre Ljubljana, Ljubljana, Slovenia. METHODS: The registry included patients with type 1 diabetes who had converted from multiple daily injection (MDI) to CSII. Patients with complete data sets covering a period of ≥3 years were included in the study (n=184). Complications, glycaemic control and insulin dose during CSII were compared with data obtained during MDI. RESULTS: CSII resulted in significant reductions in glycosyated haemoglobin level and total daily insulin dose. The mean number of severe hypoglycaemic episodes during CSII was 0.17 per patient per year. CONCLUSIONS: Treatment of adults with type 1 diabetes mellitus by CSII can improve glycaemic control and reduce insulin requirements compared with MDI, however patient selection, education and continuous care are important parts of this therapy.

Adipocytokines and insulin resistance across various degrees of glucose tolerance in pregnancy.

OBJECTIVE: Gestational diabetes mellitus is characterized by progressive insulin resistance. Adipocytokines are thought to be associated with insulin resistance. This cross-sectional study evaluated the associations between serum concentrations of several adipocytokines and insulin resistance at different stages of glucose tolerance in pregnancy, using the homeostasis model assessment of insulin resistance (HOMA-IR) as a reference. METHODS: According to oral glucose tolerance test results, 74 pregnant women were divided into three groups: normal glucose tolerance (n = 25); intermediate glucose tolerance (n = 19); gestational diabetes mellitus (n = 30). Adiponectin, leptin, resistin, visfatin and retinol-binding protein 4 (RBP4) concentrations were measured using enzyme-linked immuno sorbent assays. RESULTS: Groups were comparable regarding age, week of gestation and body mass index before gestation. There were statistically significant between-group differences in HOMA-IR, but no significant differences regarding serum adipocytokine concentrations. CONCLUSIONS: Adipo nectin, leptin, resistin, visfatin and RBP4 were not associated with the degree of glucose tolerance in pregnancy. Concentrations of these adipocytokines are not sufficiently sensitive to replace HOMA- IR in pregnancy.

Comparison of alterations in insulin signalling pathway in adipocytes from Type II diabetic pregnant women and women with gestational diabetes mellitus.

AIMS/HYPOTHESIS: The cellular mechanisms for the insulin resistance in pregnancy and gestational diabetes mellitus are not known. The membrane protein plasma cell glycoprotein PC-1 has been identified as an inhibitor of insulin receptor tyrosine kinase activity and could have a role in insulin resistance. This study aimed to examine the effects of insulin on glucose transport and changes in insulin receptor tyrosine phosphorylation, IRS-1 and PC-1. METHODS: Adipocytes were obtained either during elective cesarean section from three groups of subjects (Type II diabetic pregnant women ( n=6) women with gestational diabetes mellitus ( n=10) and pregnant women with normal glucose tolerance ( n=6) as pregnant control subjects) or during elective gynaecological surgery from non-pregnant ( n=6) control subjects. RESULTS: Insulin stimulated glucose transport was reduced by 50% in women with gestational diabetes mellitus and 70% in pregnant women with Type II diabetes, compared to the non-pregnant control subjects. After maximal insulin stimulation of adipocytes, IRTK phosphorylation was reduced by 29.5% in women with gestational diabetes mellitus and 44.5% in women with Type II diabetes, compared to the non-pregnant control subjects. We also found that IRS-1 phosphorylation was reduced by 32% and 48%, respectively. On the other hand, PC-1 content in adipocytes in women with gestational diabetes mellitus increased by 320% and 668% in Type II diabetic women, compared to the non-pregnant control subjects. CONCLUSIONS/INTERPRETATION: Our results indicate that women with gestational diabetes mellitus and Type II diabetes have increased PC-1 content and suggest that this could contribute to lower phosphorylation levels of IRTK and IRS-1. Furthermore, these postreceptor defects in insulin signalling pathway are greater in both groups compared to the women with normal pregnancy. However, results from women with Type II diabetes show that pre-existing insulin resistance lead to an even greater deterioration of the signalling pathway.

Thiazolidinedione treatment prevents free fatty acid-induced insulin resistance in male wistar rats.

We sought to ascertain whether pretreatment with troglitazone (20 days) could prevent acute free fatty acid (FFA)-induced insulin resistance in male Wistar rats. Animals were divided into three groups: 1) control, 2) FFA infusion alone (FFA1), and 3) thiazolidinedione (TZD)-treated + FFA infusion (FFA1). Days before a hyperinsulinemic-euglycemic clamp, all animals were cannulated in the jugular vein (infusion) and carotid artery (sampling). Animals were allowed 5 days to recover from surgery and fasted 12 h before the experiment. Glucose (variable), insulin (40 mU. kg(-1). min(-1)), and Liposyn (heparinized 10% lipid emulsion) infusions were initiated simultaneously and continued from 0-120 min. Steady-state glucose, 8.3 +/- 0.14 mmol/l, and insulin concentrations, 7.3 +/- 2.45 nmol/l, were the same between groups. Interestingly, steady-state FFA levels were significantly lower in animals pretreated with TZD compared with FFA alone (1.83 +/- 0.26 vs. 2.96 +/- 0.25 mmol/l; P = 0.009), despite matched intralipid infusion rates. A second group of TZD-treated animals (TZD + FFA2) were infused with intralipid at a higher infusion rate (44%) to match the arterial concentrations of FFA1. The glucose infusion and insulin-stimulated glucose disposal rates (GDRs) were significantly decreased (40%) for untreated Liposyn infused (FFA1) compared with control rats. In addition, insulin receptor substrate-1 (IRS-1) phosphorylation and IRS-1-associated phosphatidylinositol (PI) 3-kinase activity was significantly reduced, 30-50%, in FFA1 rats. TZD pretreatment prevented the FFA-induced decrement in insulin signaling. Fatty acid translocase (FAT/CD36) also was significantly reduced (56%) in untreated FFA1 rats after the clamp but remained identical to control values for TZD-treated rats. In conclusion, acutely elevated FFA levels 1) induced a significant reduction in tracer-determined GDR paralleled by impaired tyrosine phosphorylation of IRS-1 and reduced IRS-1-associated PI 3-kinase activity and 2) induced a significant reduction in FAT/CD36 total protein. TZD pretreatment prevented FFA-induced decrements in insulin action and prevented the reduction in FAT/CD36 protein.

Insulinoma induced hypoglycemia in a type 2 diabetic patient.

Insulinoma in a patient with pre-existing diabetes mellitus is extremely rare. We report a case of an insulinoma in a patient with type 2 diabetes mellitus who after 14 years of sulfonylurea treatment experienced recurrent episodes of hypoglycemia. Endogenous hyperinsulinism was confirmed and endoscopic ultrasonography identified a pancreatic tumor, which was positive for insulin by immuno-histological staining. After surgical excision of the tumor, no further hypoglycemic attacks occurred. Loss of body weight after removal of the tumor correlated with a dramatic reduction of insulin resistance to such a degree that diet alone proved sufficient for satisfactory glycemic control.

The osmotic shock-induced glucose transport pathway in 3T3-L1 adipocytes is mediated by gab-1 and requires Gab-1-associated phosphatidylinositol 3-kinase activity for full activation.

Osmotic shock treatment of 3T3-L1 adipocytes causes an increase in glucose transport activity and translocation of GLUT4 protein similar to that elicited by insulin treatment. Insulin stimulation of GLUT4 translocation and glucose transport activity was completely inhibited by wortmannin, however, activation by osmotic shock was only partially blocked. Additionally, we have found that the newly identified insulin receptor substrate Gab-1 (Grb2-associated binder-1) is tyrosine-phosphorylated following sorbitol stimulation. Treatment of cells with the tyrosine kinase inhibitor genistein inhibited osmotic shock-stimulated Gab-1 phosphorylation as well as shock-induced glucose transport. Furthermore, pretreatment with the selective Src family kinase inhibitor PP2 completely inhibited the ability of sorbitol treatment to cause tyrosine phosphorylation of Gab-1. We have also shown that microinjection of anti-Gab-1 antibody inhibits osmotic shock-induced GLUT4 translocation. Furthermore, phosphorylated Gab-1 binds and activates phosphatidylinositol 3-kinase (PI3K) in response to osmotic shock. The PI3K activity associated with Gab-1 was 82% of that associated with anti-phosphotyrosine antibodies, indicating that Gab-1 is the major site for PI3K recruitment following osmotic shock stimulation. Although wortmannin only causes a partial block of osmotic shock-stimulated glucose uptake, wortmannin completely abolishes Gab-1 associated PI3K activity. This suggests that other tyrosine kinase-dependent pathways, in addition to the Gab-1-PI3K pathway, contribute to osmotic shock-mediated glucose transport. To date, Gab-1 is the first protein identified as a member of the osmotic shock signal transduction pathway.

Insulin-mediated cellular insulin resistance decreases osmotic shock-induced glucose transport in 3T3-L1 adipocytes.

Similar to insulin, osmotic shock treatment of 3T3-L1 adipocytes causes translocation of GLUT4 protein to the plasma membrane and an increase in glucose transport activity. In our study, we evaluated the effect of chronic insulin treatment on the osmotic shock signaling pathway leading to GLUT4 translocation and glucose uptake. We found that chronic administration of insulin to the adipocytes induced cellular resistance to osmotic shock-stimulated GLUT4 translocation and glucose transport. We found that chronic insulin treatment attenuated shock-induced Gab-1 tyrosine phosphorylation. Furthermore, chronic insulin exposure led to a marked impairment in the ability of Gab-1 to associate with p85 subunit of PI 3-kinase in response to acute shock and insulin stimulation. Cells that were chronically treated with insulin showed a 70% and a 61% decrease in Gab-1 associated PI 3-kinase activity in shock- vs. insulin-treated cells, respectively. In addition, we found that chronic insulin treatment inhibited both insulin- and osmotic shock-induced membrane ruffling, indicating that two PI 3-kinase dependent effects, GLUT4 translocation and membrane ruffling are decreased in chronically insulin-treated cells. The results described above clearly demonstrate that chronic insulin treatment induces a state of cellular resistance to osmotic shock signal transduction.