The role of the growth hormone-insulin-like growth factor axis in glucose homeostasis

In vitro and in silico studies of silver nanoparticles (AgNPs) from Allium sativum against diabetes

In the present study, the silver nanoparticles (AgNPs) were synthesized from the bulbs of Allium sativum, characterized by UV-visible spectroscopy, FT-IR, SEM, HR-TEM, EDAX analysis and investigated its action on the inhibition of starch digestion. The results proved that the biosynthesized nanoparticles were uniformly dispersed, spherical shaped with the size ranging from 10 to 30 nm. The phytochemical and FT-IR analysis showed the presence of phenols, terpenoids, and amino acids in the synthesized AgNPs. The cytotoxicity analysis revealed that the synthesized AgNPs were non-toxic to the normal cells. The synthesized AgNPs exhibited significant free radical scavenging activity. The in vitro antidiabetic activity showed that the synthesized AgNPs increased glucose utilization, decreased hepatic glucose production, inhibited the activity of starch digestive enzymes such as α-amylase and α-glucosidase, and were not involved in the stimulation of pancreatic cells for the secretion of insulin. The in silico antidiabetic activity analysis (molecular docking) also revealed that the silver atoms of the AgNPs interacted with the amino acid residues of α-amylase, α-glucosidase, and insulin. The present study proved that the AgNPs synthesized from A. sativum have prominent antidiabetic activity in terms of reducing the hyperglycemia through the increased glucose utilization, decreased hepatic glucose production, and the inhibition of α-amylase and α-glucosidase enzymes. So it can be used as a promising nanomedicine for the treatment of diabetes.

Bronchopulmonary Dysplasia and Impaired Neurodevelopment-What May Be the Missing Link?

Bronchopulmonary dysplasia (BPD) and poor neurodevelopmental outcome after preterm birth are closely associated. However, mechanistic links are uncertain. We are exploring the hypothesis that decreased circulating insulin-like growth factor (IGF)-1 after preterm birth due to the abrupt end of supply by the placenta impairs growth during critical windows of development in most organs, including the lung and brain. Throughout gestation, the fetus uses glycolysis as its main source of energy. Metabolism is mainly stopped at pyruvate, which serves as a "metabolic crossroad", allowing for the production of amino acids and other "building blocks" for new cells. Metabolic pathways are differentially regulated in the nucleus and the cytoplasm. The ratio between pyruvate dehydrogenase (PDH) and pyruvate dehydrogenase kinase (PDK) determines the biochemical activity which irreversibly metabolizes pyruvate to acetyl-co-A. Metabolites in the nucleus modulate epigenetic remodeling, an essential mechanism of normal growth and maturation during development. IGF-1 has been shown to contribute significantly to the development of virtually all organs, especially related to the regulation of microvascular growth, based on extensive studies of the brain, retina, lung, and intestine. With a preterm birth, the abrupt withdrawal of the placental supply of IGF-1 and its local production directly affects metabolism and microvascular development, which may contribute to a high risk for organ maldevelopment and injury after birth. We speculate that reduced bioavailability of IGF-1 is a possible link between lung and brain development disruption and increases susceptibility for major pulmonary and neurocognitive morbidities in preterm babies. KEY POINTS: · Metabolic changes inherent to prterm birth may cause epigenetic changes which cause "dysmaturational" development.. · IGF-1 may be the potential link between BPD and brain development.. · The ratio between pyruvate dehydrogenase and pyruvate dehydrogenase kinase determines the biochemical activity..

Association between gestational diabetes mellitus and bioavailability of insulin-like growth factors and role of their binding proteins

OBJECTIVE

Insulin-like growth factors (IGFs) are involved in regulating growth and metabolism and increase insulin sensitivity, improve glucose metabolism, and are potentially related to gestational diabetes mellitus (GDM) and its complications for mothers and fetuses.

DESIGN

This study aimed to assess serum levels and cord blood levels of IGF system components in pregnant women with (39 participants) and without GDM (22 participants). Blood samples were obtained at 28-32 and 36-38 weeks of gestation and 6-12 months after delivery. Cord blood samples were obtained during delivery. Results between both groups as well as between single visits were statistically compared.

RESULTS

Both IGF1 and IGF2 maternal serum levels did not differ between the GDM and non-GDM groups. However, levels of IGF-binding proteins (IGFBPs) were different. IGFBP4 levels were decreased during pregnancy and after delivery in women with GDM, while IGFBP7 levels were increased during pregnancy in women with GDM. Cord blood IGFBP3 and IGFBP7 levels were increased (p < 0.001 for IGFBP3, p = 0.003 for IGFBP7), while IGFBP4 levels were decreased (p < 0.001) in the GDM group compared with the non-GDM group.

CONCLUSIONS

Although IGF levels did not differ, changes in their function level could still persist possibly because of the effects of the binding proteins, especially their promoting or inhibitory effects on IGFs. These results should be considered in interpretation of IGF levels.

Growth Hormone and Counterregulation in the Pathogenesis of Diabetes

PURPOSE OF REVIEW

Canonical growth hormone (GH)-dependent signaling is essential for growth and counterregulatory responses to hypoglycemia, but also may contribute to glucose homeostasis (even in the absence of hypoglycemia) via its impact on metabolism of carbohydrates, lipids and proteins, body composition, and cardiovascular risk profile. The aim of this review is to summarize recent data implicating GH action in metabolic control, including both IGF-1-dependent and -independent pathways, and its potential role as target for T2D therapy.

RECENT FINDINGS

Experimental blockade of the GHR can modulate glucose metabolism. Moreover, the soluble form of the GH receptor (GHR, or GHBP) was recently identified as a mediator of improvement in glycemic control in patients with T2D randomized to bariatric surgery vs. medical therapy. Reductions in GHR were accompanied by increases in plasma GH, but unchanged levels of both total and free IGF-1. Likewise, hepatic GHR expression is reduced following both RYGB and VSG in rodents. Emerging data indicate that GH signaling is important for regulation of long-term glucose metabolism in T2D. Future studies will be required to dissect tissue-specific GH signaling and sensitivity and their contributions to systemic glucose metabolism.

Beneficial effects of cinnamon and its extracts in the management of cardiovascular diseases and diabetes

Cardiovascular diseases (CVDs) and diabetes are the leading causes of death worldwide, which underlines the urgent necessity to develop new pharmacotherapies. Cinnamon has been an eminent component of spice and traditional Chinese medicine for thousands of years. Numerous lines of findings have elucidated that cinnamon has beneficial effects against CVDs in various ways, including endothelium protection, regulation of immune response, lowering blood lipids, antioxidative properties, anti-inflammatory properties, suppression of vascular smooth muscle cell (VSMC) growth and mobilization, repression of platelet activity and thrombosis and inhibition of angiogenesis. Furthermore, emerging evidence has established that cinnamon improves diabetes, a crucial risk factor for CVDs, by enhancing insulin sensitivity and insulin secretion; regulating the enzyme activity involved in glucose; regulating glucose metabolism in the liver, adipose tissue and muscle; ameliorating oxidative stress and inflammation to protect islet cells; and improving diabetes complications. In this review, we summarized the mechanisms by which cinnamon regulates CVDs and diabetes in order to provide a theoretical basis for the further clinical application of cinnamon.

Immunoendocrine Dysregulation during Gestational Diabetes Mellitus: The Central Role of the Placenta

Gestational Diabetes Mellitus (GDM) is a transitory metabolic condition caused by dysregulation triggered by intolerance to carbohydrates, dysfunction of beta-pancreatic and endothelial cells, and insulin resistance during pregnancy. However, this disease includes not only changes related to metabolic distress but also placental immunoendocrine adaptations, resulting in harmful effects to the mother and fetus. In this review, we focus on the placenta as an immuno-endocrine organ that can recognize and respond to the hyperglycemic environment. It synthesizes diverse chemicals that play a role in inflammation, innate defense, endocrine response, oxidative stress, and angiogenesis, all associated with different perinatal outcomes.

Insulin-Like Growth Factor 1 (IGF-1) Signaling in Glucose Metabolism in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common aggressive carcinoma types worldwide, characterized by unfavorable curative effect and poor prognosis. Epidemiological data re-vealed that CRC risk is increased in patients with metabolic syndrome (MetS) and its serum components (e.g., hyperglycemia). High glycemic index diets, which chronically raise post-prandial blood glucose, may at least in part increase colon cancer risk via the insulin/insulin-like growth factor 1 (IGF-1) signaling pathway. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. Hyperactivated glucose uptake and aerobic glycolysis (the Warburg effect) are considered as a one of six hallmarks of cancer, including CRC. However, the role of insulin/IGF-1 signaling during the acquisition of the Warburg metabolic phenotypes by CRC cells is still poorly understood. It most likely results from the interaction of multiple processes, directly or indirectly regulated by IGF-1, such as activation of PI3K/Akt/mTORC, and Raf/MAPK signaling pathways, activation of glucose transporters (e.g., GLUT1), activation of key glycolytic enzymes (e.g., LDHA, LDH5, HK II, and PFKFB3), aberrant expression of the oncogenes (e.g., MYC, and KRAS) and/or overexpression of signaling proteins (e.g., HIF-1, TGF-β1, PI3K, ERK, Akt, and mTOR). This review describes the role of IGF-1 in glucose metabolism in physiology and colorectal carcinogenesis, including the role of the insulin/IGF system in the Warburg effect. Furthermore, current therapeutic strategies aimed at repairing impaired glucose metabolism in CRC are indicated.

The IGF-1/GH-GLUTs-plasma glucose regulating axis in hybrid grouper (Epinephelus fuscoguttatus♀ × epinephelus lanceolatus♂) fed a high-carbohydrate diet

The carnivorous teleost fish is often intolerant to high levels of postprandial plasma glucose. This study aimed to evaluate the effects of insulin-like growth factor-1 (IGF-1) and growth hormone (GH) administrations on plasma glucose levels and expression of glucose transporters (GLUTs) in various tissues of hybrid grouper, and hence to further clarify the hormone-GLUTs-plasma glucose regulating axis. Twenty-four experimental fish (average body weight: 77.5 ± 5.4 g) were selected and injected with recombinant human IGF-1 (0.2 μg/g body weight) and PBS (0.01 mol/L) in enterocoelia, respectively, and in the GH injected experiment, the same quantity of fish (average body weight: 103.8 ± 5.8 g) were administrated with GH at a dose of 0.5 μg/g body weight or with PBS at a dose of 0.01 mol/L. Results showed that plasma glucose level was significantly (P < 0.05) declined by the IGF-1 administration but elevated by the GH administration. Plasma IGF-1 concentration was significantly (P < 0.01) elevated by the IGF-1 administration, while GH concentration did not significantly (P ≥ 0.05) respond to the GH administration. The relative mRNA levels of insulin-like growth factor-1 receptor a (IGF-Ra) in liver and muscle were decreased significantly with the IGF-1 administration, and a similar variation tendency was also found in insulin-like growth factor-1 receptor b (IGF-Rb) in liver, muscle and adipose tissues. Besides, the relative mRNA level of insulin receptor (IRS) in liver was significantly increased in the IGF-1 administrated group. After the GH administration, the mRNA levels of hepatic growth factor receptor 2 (GHR2) and IGF-1 were significantly elevated. As for GLUTs, the relative mRNA levels of GLUT1 and GLUT2 in liver were obviously elevated by the IGF-1 administration, while the mRNA level of GLUT4 in muscle was reduced. In liver, the protein levels of GLUT1, 2 and 4 were significantly elevated by the IGF-1 administration, and in adipose, only GLUT1 was observed to have a significantly increased protein level. The mRNA expression of GLUTs was less affected by the GH administration. The protein level of GLUT1 in liver was significantly reduced by the GH administration, while in adipose, it was significantly increased. The protein level of GLUT2 in liver or adipose showed an opposite variation as that of GLUT1. Overall, IGF-1 had a hypoglycemic effect on hybrid grouper, and this probably was through up-regulating the protein levels of hepatic GLUT1, 2 and 4 and adipose GLUT1. GH showed an opposite role in regulating plasma glucose level as IGF-1.

Quercetin‑conjugated superparamagnetic iron oxide nanoparticles modulate glucose metabolism-related genes and miR-29 family in the hippocampus of diabetic rats

Quercetin (QC) is a dietary bioflavonoid that can be conjugated with nanoparticles to facilitate its brain bioavailability. We previously showed that quercetin-conjugated superparamagnetic iron oxide nanoparticles (QCSPIONs) reduced the level of blood glucose in diabetic rats. Glucose transporters (GLUTs), insulin-like growth factor-1 (IGF-1), and microRNA-29 (miR-29) play a critical role in brain glucose homeostasis. In the current study, we examined the effects of QCSPION on the expression of glucose metabolism-related genes, and the miR-29 family as a candidate regulator of glucose handling in the hippocampus of diabetic rats. Our in silico analyses introduce the miR-29 family as potential regulators of glucose transporters and IGF-1 genes. The expression level of the miR-29 family, IGF-1, GLUT1, GLUT2, GLUT3, and GLUT4 were measured by qPCR. Our results indicate that diabetes significantly results in upregulation of the miR-29 family and downregulation of the GLUT1, 2, 3, 4, and IGF-1 genes. Interestingly, QCSPIONs reduced miR-29 family expression and subsequently enhanced GLUT1, 2, 3, 4, and IGF-1expression. In conclusion, our findings suggest that QCSPION could regulate the expression of the miR-29 family, which in turn increases the expression of glucose transporters and IGF-1, thereby reducing diabetic complications.

Doege-Potter Syndrome with a Benign Solitary Fibrous Tumor: A Case Report and Literature Review

Doege-Potter syndrome is a rare paraneoplastic syndrome that is often diagnosed incidentally during the workup of hypoglycemia of unclear etiology. It is characterized by a non-islet cell tumor hypoglycemia secondary to excessive production of partially processed IGF-II hormone from a solitary fibrous tumor (SFT). Often these tumors are intrathoracic, benign, and asymptomatic. Occasionally they present as a paraneoplastic event; hypertrophic osteoarthropathy in Pierre-Marie-Bamberger syndrome and hypoglycemia in Doege-Potter syndrome. The NAB2-STAT6 gene fusion is the hallmark of the SFT. Complete surgical resection of the tumor often results in resolution of symptoms and cure in most cases. Here we present the case of an 83-year-old non-diabetic female with recurrent syncopal events who was diagnosed with the Doege-Potter syndrome secondary to a SFT of pleura. Her tumor was positive for NAB2-STAT6 gene fusion on RT-PCR. Following the resection of the giant tumor mass, she became symptom-free within 24 h, and has remained asymptomatic at 4 months follow-up.

Type of training has a significant influence on the GH/IGF-1 axis but not on regulating miRNAs

The growth hormone (GH)/insulin-like growth factor-1 axis is responsible for glucose homeostasis. In the present study we assessed the expression levels of miRNA-124, miRNA-210 and miRNA-375 and immunoexpression of IGFBP-3 in relation to the concentrations of IGF-1 and glucose in athletes performing different types of effort. Sixty-six young male athletes (age 25.4±4.1 years) were divided into: group EN (33 male athletes; age 25.6±4.4 years) with endurance-type efforts (disciplines: triathlon, long distance running, cycling) and group ST (33 male athletes; age 25.2±3.9 years) with strength-type efforts (disciplines: weightlifting, body building, CrossFit). The control group consisted of 28 non-training men (age 29.1±4.7 years). Statistically significantly higher IGF-1 concentration and lower glucose concentration (P<0.05) in serum were observed in the group of athletes (vs. controls). Immunoexpression of IGFBP-3 was higher in athletes (vs. controls), and a higher value of immunoexpression was obtained in athlete group ST vs. group EN (P>0.05). Levels of expression of miRNA-210 and miRNA-375 were higher in athletes vs. controls (P>0.05). The obtained data confirmed the importance of the somatotropic axis in the regulation of metabolic adaptation to physical exercise. The detected variation in the concentrations and expression levels of the studied molecules involved in the somatotropic axis in athletes confirmed the role of the somatotropic axis in adaptation to physical effort. Statistically significant reduction of glucose concentration and the highest expression of IGF-1in serum in athletes suggest the anabolic effect of IGF-1 through insulin receptors on many tissues under the influence of moderate physical exercises (mainly during resistance training).

Mechanisms of putative IGF-I receptor resistance in active acromegaly

Acromegaly is a disease characterized by overproduction of growth hormone (GH). As a consequence of excessive GH secretion, circulating insulin-like growth factor-I (IGF-I) is elevated in active (untreated) acromegaly. IGF-I is often used as a marker of disease activity and growth hormone status in acromegaly. Although IGF-I can directly improve insulin sensitivity and glucose uptake in muscles, the excessive GH secretion in active acromegaly frequently leads to insulin resistance, glucose intolerance and even diabetes. In this review evidence will be discussed that in active acromegaly chronically elevated IGF-I, insulin and soluble Klotho (S-Klotho) levels play a pathophysiological role in the development of IGF-I receptor (IGF-IR) resistance. It is postulated that as soon as circulating IGF-I, insulin and S-Klotho rise above a certain level the IGF-IR becomes relatively resistant to actions of IGF-I. The development of a degree of IGF-IR resistance for metabolic actions may help to explain why in active acromegaly diabetogenic effects of GH predominate and are not completely counteracted and neutralized by elevated circulating levels of IGF-I. Further studies are necessary in order to support this hypothesis.

Insulin-Like Growth Factor Dysregulation Both Preceding and Following Type 1 Diabetes Diagnosis

Insulin-like growth factors (IGFs), specifically IGF1 and IGF2, promote glucose metabolism, with their availability regulated by IGF-binding proteins (IGFBPs). We hypothesized that IGF1 and IGF2 levels, or their bioavailability, are reduced during type 1 diabetes development. Total serum IGF1, IGF2, and IGFBP1-7 levels were measured in an age-matched, cross-sectional cohort at varying stages of progression to type 1 diabetes. IGF1 and IGF2 levels were significantly lower in autoantibody (AAb)⁺ compared with AAb^- relatives of subjects with type 1 diabetes. Most high-affinity IGFBPs were unchanged in individuals with pre-type 1 diabetes, suggesting that total IGF levels may reflect bioactivity. We also measured serum IGFs from a cohort of fasted subjects with type 1 diabetes. IGF1 levels significantly decreased with disease duration, in parallel with declining β-cell function. Additionally, plasma IGF levels were assessed in an AAb⁺ cohort monthly for a year. IGF1 and IGF2 showed longitudinal stability in single AAb⁺ subjects, but IGF1 levels decreased over time in subjects with multiple AAb and those who progressed to type 1 diabetes, particularly postdiagnosis. In sum, IGFs are dysregulated both before and after the clinical diagnosis of type 1 diabetes and may serve as novel biomarkers to improve disease prediction.

Encapsulation of cinnamon oil in whey protein counteracts the disturbances in biochemical parameters, gene expression, and histological picture of the liver and pancreas of diabetic rats

This study aimed to evaluate the protective role of encapsulated cinnamon oil emulsion (COE) in whey protein concentrate (WPC) against the disturbance in lipid profile, oxidative stress markers, and gene expression in streptozotocin (STZ)-treated rats. COE was analyzed using GC-MS, and the emulsion was prepared and characterized. In the in vivo study, six groups of male rats were treated orally for 4 weeks, including the control group, the group treated with STZ (D-rats), the groups received a low or high dose of COE (200 or 400 mg/kg B.w.), and the D-rats groups received COE at the low or high dose. Blood and tissue samples were collected after the end of the treatment period for biochemical, genetical, and histological analyses. The GC-MS results revealed that the major components of the oil were cinnamaldehyde, 1,8 cineole, acetic acid, 1,7,7-trimethylbicyclo[2.2.1]hept2yl ester, α-Pinene, and α-Terpineol. The size, zeta potential, and polydispersity index (PDI) of COE were 240 ± 1.03 nm, - 7.09 ± 0.42, and 0.36, respectively. The in vivo results revealed that COE at the two tested doses improved the levels of glucose, insulin, amylase, lipid profile, hepatic MDA, SOD, and GSH. COE also downregulated hepatic GLU2, FAS, SREBP-1c, and PEPCK gene expression and upregulated IGF-1 mRNA expression in diabetic rats in a dose-dependent manner. Moreover, COE improved and the histological picture of the liver and pancreas. It could be concluded that COE overcomes the disturbances in biochemical, cytological, and histopathological changes in D-rats via the enhancement of antioxidant capacity; reduces the oxidative stress; modulates the concerned gene expression; and may be promising to develop new drugs for diabetic treatment.

Prevalence of diabetes among children treated with growth hormone in Israel

AIMS

To determine the long-term risk of diabetes in a cohort of children treated with recombinant human growth hormone in Israel, using data from the Israeli National Diabetes Register.

METHODS

Between 1988 and 2009, 2513 children were approved for growth hormone treatment. They were assigned to one of two groups. The first group included children treated for isolated growth hormone deficiency and who were small for gestational age and the second included those treated for multiple pituitary hormone deficiency, chronic renal failure, Turner syndrome or Prader-Willi syndrome. The cohort was cross-linked with the Israeli National Diabetes Register for 2014 (mean follow-up duration 12.1±5.3 years), and prevalent cases of diabetes were identified. Standardized prevalence ratios for diabetes were calculated for people aged 10-29 years.

RESULTS

In 2014, a total of 23 individuals were identified with diabetes (four with pre-existing diabetes, seven developed diabetes before age 17 years and 12 developed it at a later age). In the isolated growth hormone deficiency and small-for-gestational-age group there was no difference in the prevalence of diabetes compared with the general population (standardized prevalence ratio 2.05, 95% CI 0.94-3.89). In the group that included people with multiple pituitary hormone deficiency, chronic renal failure, Turner syndrome and Prader-Willi syndrome there was a significantly higher diabetes prevalence (standardized prevalence ratio 11.94, 95% CI 6.53-20.00) compared with the general population.

CONCLUSIONS

No difference in diabetes prevalence was found in the isolated growth hormone deficiency and small-for-gestational-age group, compared with the general population. Children treated with growth hormone with pre-existing risk factors had an increased prevalence of diabetes. It is advisable to monitor blood glucose levels closely during and after growth hormone treatment, especially in such children.

Insulin-like growth factor axis in pregnancy and gestational diabetes mellitus

The insulin-like growth factor (IGF) is involved in the regulation of growth and metabolism. The aim of this study was to determine selected parameters of IGF system at systemic and local levels [subcutaneous (SAT) and visceral adipose tissue (VAT)] to assess its possible role in gestational diabetes mellitus (GDM). 37 pregnant women (21 with GDM and 16 without GDM) and 15 age-matched non-pregnant females were included in the study. Blood samples were taken in 28-32 and 36-38 weeks of gestation and 6-12 months after delivery. SAT and VAT samples were obtained during delivery or surgery. Compared with non-pregnant women, serum IGF-1 and IGFBP-3 were increased in both groups of pregnant women. IGF-2 was elevated only in GDM women from 36 weeks of gestation culminating 6 months after delivery (p=0.003). Serum IGFBP-3 was increased and IGFBP-4 decreased in GDM women vs. pregnant women without GDM during the whole study (IGFBP-3: p?0.001 for GDM vs. non-GDM; IGFBP-4: p=0.004 for GDM vs. non-GDM). Pregnant women with GDM had decreased mRNA expression of IGF-1, IGF-1R and IGF-2R and IGFBP-4 in VAT and IGF-1R in SAT compared to pregnant women without GDM. Changes in local activity of IGF are associated with the development of GDM.

Insulin-like growth factor-1 and non-alcoholic fatty liver disease: a systemic review and meta-analysis

AIM

The prevalence of non-alcoholic fatty liver disease (NAFLD) is rapidly increasing worldwide. A number of researchers have studied the relationship between Insulin-like growth factor-1(IGF-1) and NAFLD. However, the results are controversial. This meta-analysis, aimed to systemically evaluate the correlation between IGF-1 and NAFLD.

METHODS

We searched for four online databases: PubMed, Web of Science, Embase and CNKI up to Feb 2018. We then applied a random-effects model to evaluate the overall effect sizes by calculating Standard mean difference (SMD) and its 95% confidence intervals (CIs).

RESULTS

Twelve articles were included in this meta-analysis. The pooled analysis showed that the level of IGF-1 in the control group was significantly higher than that in the NAFLD group. (SMD: 1.00, 95% CI: 0.54-1.46, P < 0.00001). However, significant heterogeneity was discovered among the included studies (P < 0.00001, I² = 96%). Then a series of subgroup analyses were performed. Compared to the nonalcoholic steatohepatitis (NASH) group, the level of IGF-1 was significantly higher in the Non- or probable-NASH group (SMD: 1.42, 95% CI: 0.25-2.58, P = 0.02). The level of IGF-1 in patients with increased insulin resistance (SMD: 0.49; 95% CI: 0.36-0.63; P < 0.00001) and high Body Mass Index (SMD: 0.50; 95% CI: 0.22-0.79; P < 0.05) were significantly lower than healthy control. In addition, the same conclusion were found in studies carried out in Asia and Europe (Asia: SMD: 0.69, 95% CI: -0.29-1.66, P = 0.17; Europe: SMD: 0.89, 95% CI: 0.41-1.38, P < 0.05).

CONCLUSION

The level of IGF-1 is down-regulated in NAFLD patients compared to healthy controls, suggesting that IGF-1 might be used as a potential biomarker and therapeutic target for NAFLD.

Pleiotropic roles of the insulin-like growth factor axis in type 1 diabetes

PURPOSE OF REVIEW

We review studies demonstrating lowered levels of insulin-like growth factors (IGFs) in patients with recent-onset type 1 diabetes (T1D) and discuss their potential roles in the disorder's pathogenesis.

RECENT FINDINGS

IGFs have long been recognized as a class of hormones that promote growth, development, and cellular metabolism throughout the human body. More recently, studies have noted an association between reduced pancreatic weight/volume and T1D. Thus, we believe it is important to understand pancreatic regulation of IGF expression and bioavailability, as well as the impact of IGFs on pancreatic growth and islet health. Additional studies of IGFs have been extended to their influence on the inflammatory/regulatory balance of monocytes, B cells, and T cells; features which have been previously established to show dysregulation in settings of T1D.

SUMMARY

These data suggest that IGFs may prevent known impairments in the pancreas and immune system in T1D and underscore the need to extend these studies, some of which were performed in health or other autoimmune diseases, toward T1D specifically. Collectively, the work emphasized here support the potential therapeutic use of IGFs in T1D prevention efforts as pancreatic growth factors and/or immunoregulatory agents.

Insulin-like growth factor-1 is inversely associated with liver fibrotic markers in patients with type 2 diabetes mellitus

AIMS/INTRODUCTION

Insulin-like growth factor-1 (IGF-1) regulates mitochondrial function, oxidative stress, inflammation, stellate cells and insulin sensitivity in the liver, and it might be associated with liver fibrosis from non-alcoholic steatohepatitis. In contrast, type 2 diabetes mellitus is closely associated with the progression from non-alcoholic fatty liver to non-alcoholic steatohepatitis and cirrhosis, so careful evaluation of liver fibrosis is required for patients with type 2 diabetes mellitus. Therefore, we examined the relationship between IGF-1 and liver fibrosis markers in type 2 diabetes patients without obvious alcoholic consumption and determined whether IGF-1 is associated with fibrosis of non-alcoholic fatty liver disease.

MATERIALS AND METHODS

We selected 415 patients with type 2 diabetes without obvious alcohol consumption, who were admitted to Uwajima City Hospital between May 2013 and December 2016. We collected and analyzed clinical data to determine correlations between IGF-1 or IGF-1 standard deviation score and fibrosis-4 index or 7S domain of type IV collagen.

RESULTS

Multiple linear regression analysis showed that the fibrosis-4 index was inversely correlated with IGF-1 and IGF-1 standard deviation score. Furthermore, the 7S domain of type IV collagen was also inversely correlated with IGF-1 and IGF-1 standard deviation score.

CONCLUSIONS

IGF-1 was inversely correlated with liver fibrosis markers in type 2 diabetes mellitus patients without obvious alcoholic consumption. Measuring serum IGF-1 levels might help clinicians to identify type 2 diabetes mellitus patients with advanced non-alcoholic steatohepatitis.

Growth hormone signaling and action in obese versus lean human subjects

Growth hormone (GH) levels are blunted in obesity, but it is not known whether this relates to altered GH sensitivity and whether this influences the metabolic adaptation to fasting. Therefore, we investigated the effect of obesity on GH signal transduction and fasting-induced changes in GH action. Nine obese (BMI 35.7 kg/m²) and nine lean (BMI 21.5 kg/m²) men were studied in a randomized crossover design with 1) an intravenous GH bolus, 2) an intravenous saline bolus, and 3) 72 h of fasting. Insulin sensitivity (hyperinsulinemic, euglycemic clamp) and substrate metabolism (glucose tracer and indirect calorimetry) were measured in studies 1 and 2. In vivo GH signaling was assessed in muscle and fat biopsies. GH pharmacokinetics did not differ between obese and lean subjects, but endogenous GH levels were reduced in obesity. GH signaling (STAT5b phosphorylation and CISH mRNA transcription), and GH action (induction of lipolysis and peripheral insulin resistance) were similar in the two groups, but a GH-induced insulin antagonistic effect on endogenous glucose production only occurred in the obese. Fasting-induced IGF-I reduction was completely abrogated in obese subjects despite a comparable relative increase in GH levels (ΔIGF-I: lean, -66 ± 10 vs. obese, 27 ± 16 µg/l; P < 0.01; ΔGH: lean, 647 ± 280 vs. obese, 544 ± 220%; P = 0.76]. We conclude that 1) GH signaling is normal in obesity, 2) in the obese state, the preservation of IGF-I with fasting and the augmented GH-induced central insulin resistance indicate increased hepatic GH sensitivity, 3) blunted GH levels in obesity may protect against insulin resistance without compromising IGF-I status.

Insulin-Like Growth Factor Axis Biomarkers and Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

The insulin-like growth factor (IGF) axis has been implicated in glucose homeostasis. It is plausible to hypothesize that the IGF axis is involved in the development of gestational diabetes mellitus (GDM). In a systematic review of the evidence on IGF axis biomarkers in relation to GDM, we searched the PubMed and EMBASE for publications up to May 31, 2018, on the associations of circulating IGF axis biomarkers with GDM. Eligible studies must meet the pre-specified quality assessment criteria. Meta-analyses were conducted where there were at least three studies on the same biomarker at the same gestational age window-early (<20 weeks), mid (20-29 weeks), or late (30+ weeks) gestation. Twelve studies were included (484 GDM, 1755 euglycemic pregnancies). Meta-analyses showed that GDM was consistently associated with higher IGF-I concentrations in mid-gestation (six studies) and late gestation (six studies). There were only two studies on IGF-I in early gestation and GDM with inconsistent findings. GDM was associated with lower IGFBP-2 concentrations in early, mid-, or late gestation, according to data from one or two studies. GDM was associated with higher IGFBP-3 concentrations in late gestation according to a meta-analysis of five studies. There was no association with GDM for IGFBP-3 in early or mid-gestation, according to data from one study. Other IGF axis biomarkers (IGF-II, IGFBP-1,-4,-5-6, and -7) showed no or inconsistent associations, and the data at early gestation were scanty or absent. Available evidence is suggestive but inconclusive concerning whether the IGF axis is involved in the development of GDM. More studies on IGF axis biomarkers in early gestation are warranted. If a specific IGF axis molecule is proven to be involved in the development of GDM, this may point to a new molecular target for designing interventions to reduce the incidence of GDM.

Exercise Training-Induced Changes in MicroRNAs: Beneficial Regulatory Effects in Hypertension, Type 2 Diabetes, and Obesity

MicroRNAs are small non-coding RNAs that regulate gene expression post-transcriptionally. They are involved in the regulation of physiological processes, such as adaptation to physical exercise, and also in disease settings, such as systemic arterial hypertension (SAH), type 2 diabetes mellitus (T2D), and obesity. In SAH, microRNAs play a significant role in the regulation of key signaling pathways that lead to the hyperactivation of the renin-angiotensin-aldosterone system, endothelial dysfunction, inflammation, proliferation, and phenotypic change in smooth muscle cells, and the hyperactivation of the sympathetic nervous system. MicroRNAs are also involved in the regulation of insulin signaling and blood glucose levels in T2D, and participate in lipid metabolism, adipogenesis, and adipocyte differentiation in obesity, with specific microRNA signatures involved in the pathogenesis of each disease. Many studies report the benefits promoted by exercise training in cardiovascular diseases by reducing blood pressure, glucose levels, and improving insulin signaling and lipid metabolism. The molecular mechanisms involved, however, remain poorly understood, especially regarding the participation of microRNAs in these processes. This review aimed to highlight microRNAs already known to be associated with SAH, T2D, and obesity, as well as their possible regulation by exercise training.

Temporal relationships of GH, IGF-I and fructosamine concentrations in pregnant Spanish Purebred mares: A substantial contribution from the hormonal standpoint

Growth hormone (GH) and insulin-like growth factor (IGF-I) exert essential functions to maintain an adequate metabolic activity for correct placental and fetal development. Although fructosamine (FRUCT) is used in clinical evaluation to assess the glycaemic state, the relationships between GH, IGF-I and FRUCT remain unknown in the mare. Therefore, the objectives of this study were to evaluate the relationships among these parameters in pregnant mares. A total of 30 healthy Spanish Purebred mares, with an age range of 9.33 ± 3.31 years, were studied during the 11 months of gestation. Serum concentrations of GH, IGF-I and FRUCT were analyzed by EIA, competition ELISA and spectrophotometry, respectively. GH showed a biphasic pattern, the first occurred during 4th and 5th month and the second which was higher than the 1st one during the 7th, 8th and 9th month (P < 0.05). Compared to the 1st month, the IGF-I concentrations increased in the 2nd month (P < 0.05), decreased in the 3rd and 4th month and increased to reach the maximum average value in the 5th month (P < 0.05); after slight oscillations between the 6th and 8th month, IGF-I concentrations increased in the 9th month (P < 0.05), decreasing until the end of gestation. FRUCT increased progressively and significantly from the 6th month of gestation, reaching the maximum values in the last month of gestation (P < 0.05). These results suggest that alternative mechanisms other than GH and IGF-I could be involved in the regulation of glycaemic metabolism in pregnant mare.

Adipocyte JAK2 Regulates Hepatic Insulin Sensitivity Independently of Body Composition, Liver Lipid Content, and Hepatic Insulin Signaling

Disruption of hepatocyte growth hormone (GH) signaling through disruption of Jak2 (JAK2L) leads to fatty liver. Previously, we demonstrated that development of fatty liver depends on adipocyte GH signaling. We sought to determine the individual roles of hepatocyte and adipocyte Jak2 on whole-body and tissue insulin sensitivity and liver metabolism. On chow, JAK2L mice had hepatic steatosis and severe whole-body and hepatic insulin resistance. However, concomitant deletion of Jak2 in hepatocytes and adipocytes (JAK2LA) completely normalized insulin sensitivity while reducing liver lipid content. On high-fat diet, JAK2L mice had hepatic steatosis and insulin resistance despite protection from diet-induced obesity. JAK2LA mice had higher liver lipid content and no protection from obesity but retained exquisite hepatic insulin sensitivity. AKT activity was selectively attenuated in JAK2L adipose tissue, whereas hepatic insulin signaling remained intact despite profound hepatic insulin resistance. Therefore, JAK2 in adipose tissue is epistatic to liver with regard to insulin sensitivity and responsiveness, despite fatty liver and obesity. However, hepatocyte autonomous JAK2 signaling regulates liver lipid deposition under conditions of excess dietary fat. This work demonstrates how various tissues integrate JAK2 signals to regulate insulin/glucose and lipid metabolism.

The Association Between IGF-I and IGFBP-3 and Incident Diabetes in an Older Population of Men and Women in the Cardiovascular Health Study

CONTEXT

Insulin-like growth factor-I (IGF-I) has structural and functional similarities to insulin and may play a role in glucose homeostasis, along with insulin-like growth factor binding protein-3 (IGFBP-3), which binds the majority of circulating IGF-I.

OBJECTIVE

To assess whether IGF-I and IGFBP-3 are associated with a higher risk of incident diabetes in older adults.

DESIGN

Participants in the Cardiovascular Health Study (n = 3133), a cohort of adults aged ≥65 years, were observed for 16 years (n = 3133) for the development of incident diabetes. Statistical models were fit separately for men and women because of interactions with sex (P interaction: IGF-I, 0.02; IGFBP-3, 0.009) and were adjusted for relevant covariates.

SETTING

General community.

PARTICIPANTS

Older adults who were nondiabetic at baseline and who did not develop diabetes within the first year of follow-up.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Incident diabetes as measured by fasting plasma glucose (FPG) ≥126 mg/dL, non-FPG ≥200 mg/dL, use of pharmacological treatment of diabetes, or existence of two or more inpatient or three or more outpatient or (at least one inpatient and at least one outpatient) Centers for Medicare & Medicaid Services claims with the diagnostic International Classification of Diseases, Ninth Revision, Clinical Modification code of 250.xx.

RESULTS

In women, higher IGFBP-3 (hazard ratio tertile 3 vs tertile 1 = 2.30; 95% confidence interval, 1.55 to 3.40; P trend < 0.0001) was significantly associated with incident diabetes. Total IGF-I was not significantly associated with incident diabetes. In men, neither IGF-I nor IGFBP-3 was significantly associated with incident diabetes.

CONCLUSIONS

We confirmed a previously reported association between circulating IGFBP-3 and diabetes risk in the older adult population, establishing that this association is present among women but could not be shown to be associated in men.

Vitamin D increases IGF-I and insulin levels in experimental diabetic rats

INTRODUCTION AND OBJECTIVE

Previous studies have found that IGF-I may play an important role in glucose metabolism. The aim of this study is to examine the effect of vitamin D intake on the serum levels of glucose, insulin, and IGF-I in experimental diabetic rats.

MATERIAL AND METHODS

A total of 24 male Sprague-Dawley rats aged six to seven months, with an average weight of 300±30g, were randomly divided into three groups (eight rats per group). The first group served as control and the other two groups received an intraperitoneal injection of 45mg/kg streptozotocin (STZ) to develop diabetes. Then groups were treated for four weeks either with placebo or vitamin D (two injections of 20,000IU/kg).

RESULTS

At the end of the experiment, two injection of vitamin D were found to result in a significant increase in plasma cholecalciferol, which could improve hyperglycaemia and hypoinsulinemia in diabetic rats. HbA1c concentration had a slight and insignificant decrease following vitamin D intake. In addition, a significant decline was observed in the serum IGF-I level of STZ-treated rats in comparison to the controls, which was compensated in the vitamin D group. The serum vitamin D concentration was positively correlated to the changes in IGF-I level by Pearson test.

CONCLUSIONS

These data showed for the first time that vitamin D intake could significantly improve fasting plasma glucose, insulin, and IGF-I in an experimental type 1 diabetes model.

Do anabolic nutritional supplements stimulate human growth hormone secretion in elderly women with heart failure?

Growth hormone treatment has gained attention over the past decade as a treatment for heart failure. Human growth hormone (HGH) must be administered by injections (usually daily), so there is considerable advantage to stimulation of endogenous secretion by amino acid-based nutritional supplementation. However, studies investigating the effect of amino acid (AA) supplementation show conflicting results. Therefore, in this study we aimed to investigate the effect of nutritional supplementation on HGH production in elderly women with heart failure. Eight elderly women with heart failure participated in this randomized cross-over study. Plasma HGH concentration was measured before and for 4 h following ingestion of a mixture of protein, carbohydrate, and fat or an AA beverage. HGH concentration was determined with ELISA kits and AA concentrations were analyzed by Liquid Chromatography-Mass Spectrometry (LCMS). Linear mixed models was performed to analyze the effect of time, treatment, and interaction. Plasma arginine and lysine concentrations were significantly higher after consumption of the AA drink compared to the mixture of protein, carbohydrate, and fat. Nonetheless, only ingestion of the protein, carbohydrate, and fat mixture (meal replacement) increased HGH concentration. HGH concentration was increased in elderly women with heart failure following consumption of a meal replacement containing protein, carbohydrate, and fat. Consumption of a mixture of amino acids failed to increase HGH concentration despite significantly greater elevations in plasma amino acid concentrations, including arginine and lysine. The stimulatory effect of the protein/carbohydrate/fat mixture was presumably mediated by factors other than increases in free amino acid concentrations.

Serum Insulin, Glucose, Indices of Insulin Resistance, and Risk of Lung Cancer

Background: Although insulin may increase the risk of some cancers, few studies have examined fasting serum insulin and lung cancer risk.Methods: We examined serum insulin, glucose, and indices of insulin resistance [insulin:glucose molar ratio and homeostasis model assessment of insulin resistance (HOMA-IR)] and lung cancer risk using a case-cohort study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study of Finnish men. A total of 196 cases and 395 subcohort members were included. Insulin and glucose were measured in fasting serum collected 5 to 12 years before diagnosis. Cox proportional hazards models were utilized to estimate the relative risk of lung cancer.Results: The average time between blood collection and lung cancer was 9.6 years. Fasting serum insulin levels were 8.7% higher in subcohort members than cases. After multivariable adjustment, men in the fourth quartile of insulin had a significantly higher risk of lung cancer than those in the first quartile [HR = 2.10; 95% confidence interval (CI), 1.12-3.94]. A similar relationship was seen with HOMA-IR (HR = 1.83; 95% CI, 0.99-3.38). Risk was not strongly associated with glucose or the insulin:glucose molar ratio (P_trend = 0.55 and P_trend = 0.27, respectively).Conclusions: Higher fasting serum insulin concentrations, as well as the presence of insulin resistance, appear to be associated with an elevated risk of lung cancer development.Impact: Although insulin is hypothesized to increase risk of some cancers, insulin and lung cancer remain understudied. Higher insulin levels and insulin resistance were associated with increased lung cancer risk. Although smoking cessation is the best method of lung cancer prevention, other lifestyle changes that affect insulin concentrations and sensitivity may reduce lung cancer risk. Cancer Epidemiol Biomarkers Prev; 26(10); 1519-24. ©2017 AACR.

Doege-Potter syndrome: A review of the literature including a new case report

RATIONALE

We reviewed 76 published cases of Doege-Potter syndrome, and non-islet cell tumor hypoglycemia (NICTH) secondary to a solitary fibrous tumor (SFT) between 1989 and 2016, to study disease pathogenesis, diagnosis, and treatment of this rare paraneoplastic disease. Further, we report 1 new case of a patient presenting with Doege-Potter syndrome.

PATIENTS CONCERNS

The tumors originated from the pleural cavity, lung, pelvis, liver, retroperitoneum, kidney, mediastinal, the sella, uterus, bladder, intestine, mandibular, and the thigh. The most common location was the pleural cavity (left 12 cases and right 28 cases). Moreover, 28/71 (39.4%) were benign and 43/71 (60.6%) were malignant. SFTs with NICTH were more likely to be malignant and present at a higher rate than previously published (5%-10.4%). The malignancy rate of extrathoracic SFTs was higher than that of thoracic SFTs, 20 (66.7%) as compared with 23 (56.1%). Age of onset varied from 24 to 85 years (mean 59 years), with 47 males and 28 females, and gender unavailable for 1 case. When comparing clinical characteristics of patients with benign as compared malignant tumors, no significant differences in the age of onset, gender, or size of tumor were seen. Among 15/19 cases, the insulin-like growth factor II (IGF-II)/IGF-I ration was >10.0. Complete tumor resection remained the only definitive treatment.

OUTCOMES AND LESSENS

Glucocorticoids dose-dependently reduce the frequency and severity of hypoglycemic episodes. Low doses of prednisone were ineffective at relieving hypoglycemia. The effect of neoadjuvant treatment, consisting of chemoradiation, and consecutive selective embolization of vessels feeding the tumor were not identified.

Safety and metabolic effects of tesamorelin, a growth hormone-releasing factor analogue, in patients with type 2 diabetes: A randomized, placebo-controlled trial

Objective

Use of growth hormone is associated with side effects, including insulin resistance. The objective of this study was to determine whether tesamorelin, a stabilized growth hormone-releasing hormone analogue, would alter insulin sensitivity or control of diabetes.

Design

A 12-week randomized, placebo-controlled study of 53 patients with type 2 diabetes. Three treatment groups: placebo, 1 and 2 mg tesamorelin.

Measurements

Fasting glucose, glucose and insulin from oral glucose tolerance test, glycosylated hemoglobin (HbA_1c), home blood glucose, insulin-like growth factor-1, and lipids.

Main outcome measure

Relative insulin response following oral ingestion of glucose.

Results

No significant differences were observed between groups in relative insulin response over the 12-week treatment period. At Week 12, fasting glucose, HbA_1c and overall diabetes control were not significantly different between groups. In addition, relevant modifications in diabetes medications were similar between groups. Total cholesterol (-0.3±0.6 mmol/L) and non-HDL cholesterol (-0.3±0.5 mmol/L) significantly decreased from baseline to Week 12 in the tesamorelin 2 mg group (p<0.05 vs. placebo). No patient discontinued the study due to loss of diabetes control.

Conclusions

Treatment of type 2 diabetic patients with tesamorelin for 12 weeks did not alter insulin response or glycemic control.

Trial registration

ClinicalTrials.gov NCT01264497.

Combination of Recreational Soccer and Caloric Restricted Diet Reduces Markers of Protein Catabolism and Cardiovascular Risk in Patients with Type 2 Diabetes

BACKGROUND

Moderate calorie-restricted diets and exercise training prevent loss of lean mass and cardiovascular risk. Because adherence to routine exercise recommendation is generally poor, we utilized recreational soccer training as a novel therapeutic exercise intervention in type 2 diabetes (T2D) patients.

OBJECTIVE

We compared the effects of acute and chronic soccer training plus calorie-restricted diet on protein catabolism and cardiovascular risk markers in T2D.

DESIGN, SETTING AND SUBJECTS

Fifty-one T2D patients (61.1±6.4 years, 29 females: 22 males) were randomly allocated to the soccer+diet-group (SDG) or to the diet-group (DG). The 40-min soccer sessions were held 3 times per week for 12 weeks.

RESULTS

Nineteen participants attended 100% of scheduled soccer sessions, and none suffered any injuries. The SDG group showed higher levels of growth hormone (GH), free fatty acids and ammonia compared with DG. After 12 weeks, insulin-like growth factor binding protein (IGFPB)-3 and glucose levels were lower in SDG, whereas insulin-like growth factor (IGF)-1/ IGFBP-3 ratio increased in both groups. After the last training session, an increase in IGF-1/IGFBP-3 and attenuation in ammonia levels were suggestive of lower muscle protein catabolism.

CONCLUSIONS

Recreational soccer training was popular and safe, and was associated with decreased plasma glucose and IGFBP-3 levels, decreased ammoniagenesis, and increased lipolytic activity and IGF-1/IGFBP-3 ratio, all indicative of attenuated catabolism.

Bone Status in a Patient with Insulin-Like Growth Factor-1 Receptor Deletion Syndrome: Bone Quality and Structure Evaluation Using Dual-Energy X-Ray Absorptiometry, Peripheral Quantitative Computed Tomography, and Quantitative Ultrasonography

Haploinsufficiency of the insulin-like growth factor (IGF)-1 receptor (IGF1R) gene is a rare, probably under-diagnosed, cause of short stature. However, the effects of IGF1R haploinsufficiency on glucose metabolism, bone status, and metabolism have rarely been investigated. We report the case of a patient referred to our center at the age of 18 months for short stature, failure to thrive, and Silver-Russell-like phenotype. Genetic analysis did not show hypomethylation of the 11p15.5 region or uniparental disomy of chromosome 7. Growth hormone (GH) stimulation tests revealed GH deficiency, whereas IGF-1 was 248 ng/mL. r-hGH treatment showed only a slight improvement (from -4.4 to -3.5 SDS). At 10 years of age, the child was re-evaluated: CGH-array identified a heterozygous de novo 4.92 Mb deletion in 15q26.2, including the IGF1R gene. Dual-energy X-ray absorptiometry showed a normal bone mineral density z-score, while peripheral quantitative computed tomography revealed reduced cortical and increased trabecular elements. A phalangeal bone quantitative ultrasonography showed significantly reduced amplitude-dependent speed of sound and bone transmission time values. The changes in bone architecture, quality, and metabolism in heterozygous IGF1R deletion patients, support the hypothesis that IGF-1 can be a key factor in bone modeling and accrual.

Insulin-Like Growth Factor Axis and Gestational Diabetes Mellitus: A Longitudinal Study in a Multiracial Cohort

The insulin-like growth factor (IGF) axis may be implicated in glucose homeostasis, but its longitudinal profile across gestation in relation to the development of gestational diabetes mellitus (GDM) is largely unknown. We prospectively investigated IGF axis biomarkers in early-to-midpregnancy in relation to subsequent GDM risk in a case-control study of 107 case subjects with GDM and 214 control subjects without GDM, with blood sample collection at gestational weeks 10-14, 15-26, 23-31, and 33-39. Conditional logistic regression was used, adjusting for major risk factors including prepregnancy BMI. Plasma IGF-I and IGF binding protein 3 (IGFBP-3) concentrations and molar ratio of IGF-I to IGFBP-3 increased, whereas IGFBP-2 decreased throughout pregnancy. At gestational weeks 10-14, both IGF-I and IGF-I/IGFBP-3 were positively associated with GDM risk; adjusted odds ratio (OR) comparing the highest versus lowest quartile (OR_Q4-Q1) was 2.93 (95% CI 1.18, 7.30) for IGF-I and 3.31 (1.10, 9.98) for IGF-I/IGFBP-3. In contrast, higher IGFBP-2 levels were related to a substantially lower risk of GDM (OR_Q4-Q1 0.04 [0.01, 0.06]). Similar results were observed at gestational weeks 15-26. In sum, the IGF axis, IGFBP-2 in particular, may be implicated in the pathogenesis of GDM, with significant associations and incremental predictive value detected as early as gestational weeks 10-14, ∼10-18 weeks earlier before GDM is typically screened for.

Review: Insulin-like growth factor-related proteins and diabetic complications

The insulin-like growth factor system and, in particular, insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding protein-1 (IGFBP-1) are dysregulated in type 1 and type 2 diabetes. Serum IGF-I levels are low in both forms of diabetes, and this may be in part genetically determined. It is possible that the reduced serum levels of IGF-I are involved in the development of microvascular and macrovascular complications. Fasting serum IGFBP-1 levels are usually low in early type 2 diabetic patients with insulin resistance and hyperinsulinaemia but may be raised in patients with particularly poor glycaemic control and severe beta-cell failure. Treatment with IGF-I/binding protein complexes has been shown to improve glycaemic control in conjunction with insulin and may in future have a place in the treatment of diabetes, potentially to prevent diabetic complications. Serum IGFBP-1 determination may have utility in the assessment of cardiovascular risk and as an indicator for insulin resistance.

Non-islet cell tumor hypoglycemia caused by intrathoracic solitary fibrous tumor: a case report

Background

Non-islet cell tumor hypoglycemia (NICTH) is defined as a form of hypoglycemia caused by an extrapancreatic tumor. Solitary fibrous tumor (SFT) associated with hypoglycemia is rare.

Case presentation

A 76-year-old woman, who had frequently experienced hypoglycemic symptoms such as presyncope for the prior 6 months, visited our hospital to undergo detailed examinations. Her fasting glucose level was low at 49 mg/dl. The blood levels of IRI and C-peptide were also low at 0.2 μU/ml and 0.21 ng/ml, respectively. Chest computed tomography revealed a mass measuring 15 cm in the left thoracic cavity. Percutaneous needle biopsy yielded a diagnosis of intrathoracic SFT associated with NICTH. The tumor was removed by video-assisted thoracoscopic surgery. Histological examination showed a tumor composed of simple spindle-shaped cells with an irregular arrangement. Immunohistochemical staining was positive for CD34, bcl-2, and vimentin and negative for alpha SMA and mesothelin. These results confirmed the diagnosis of SFT. Her hypoglycemic symptoms resolved rapidly after surgery. The clinical course has since remained favorable with no signs of recurrence.

Conclusion

We report a case of non-islet cell tumor hypoglycemia caused by intrathoracic SFT. The high-molecular-weight IGF-II produced by the tumor has been regarded as the cause of NICTH.

Human growth hormone promotes corneal epithelial cell migration in vitro

PURPOSE

Corneal wound healing is a highly regulated process that requires the proliferation and migration of epithelial cells and interactions between epithelial cells and stromal fibroblasts. Compounds that can be applied topically to the ocular surface and that have the capability of activating corneal epithelial cells to proliferate and/or migrate would be useful to promote corneal wound healing. We hypothesize that human growth hormone (HGH) will activate signal transducers and activators of transcription-5 (STAT5) signaling and promote corneal wound healing by enhancing corneal epithelial cell and fibroblast proliferation and/or migration in vitro. The purpose of this study was to test these hypotheses.

METHODS

We studied cell signaling, proliferation, and migration using an immortalized human corneal epithelial cell line and primary human corneal fibroblasts in vitro. We also examined whether insulin-like growth factor-1 (IGF-1), a hormone known to mediate many of HGH's growth promoting actions, may play a role in this effect.

RESULTS

We show that HGH activates STAT5 signaling and promotes corneal epithelial cell migration in vitro. The migratory effect requires an intact communication between corneal epithelia and fibroblasts and is not mediated by IGF-1.

CONCLUSIONS

HGH may represent a topical therapeutic to promote corneal epithelial wound healing. This warrants further investigation.

Altered liver expression of genes involved in lipid and glucose metabolism in mice with partial IGF-1 deficiency: an experimental approach to metabolic syndrome

Background

Insulin growth factor 1 (IGF-1) has multiple effects on metabolism. Much evidence suggests that the deficiency of this hormone increases insulin resistance, impairs lipid metabolism, augments oxidative damage and deregulates the neuro-hormonal axis. An inverse relationship between IGF-1 levels and the prevalence of Metabolic Syndrome (MetS) with its cardiovascular complications has been identified. However, the underlying mechanisms linking IGF-1 and MetS are still poorly understood. In order to elucidate such mechanisms, the aim of this work was to study, in mice with partial IGF-1 deficiency, liver expression of genes involved in glucose and lipid metabolism as well as serum levels of glucose, triglycerides and cholesterol, as well as liver malondialdehyde (MDA) levels, as a marker for oxidative damage.

Methods

Three experimental groups were studied in parallel: Controls (CO), wild type mice (igf-1^+/+); untreated heterozygous mice (Hz, igf-1^+/−) and Hz (igf-1^+/−) mice treated with low doses of IGF-1 for 10 days (Hz + IGF-1).

Results

A reduction of IGF-1 serum levels in the Hz group was found, which was normalized by IGF-1 therapy. Serum levels of glucose, triglycerides and cholesterol were significantly increased in the untreated Hz group as compared to both controls and Hz + IGF-1 groups. The expression of genes involved in gluconeogenesis, glycogenolysis, lipid synthesis and transport, and catabolism were altered in untreated Hz animals and the expression of most of them was normalized by IGF-1 therapy; MDA was also significantly increased in the Hz untreated group.

Conclusions

The mere partial IGF-1 deficiency is responsible for the reduction in the expression of genes involved in glucose and lipid metabolism, resulting in dyslipidemia and hyperglycemia. Such genetic alterations may seriously contribute to the establishment of MetS.

Food intake and appetite control in a GH-transgenic zebrafish

The biological actions of growth hormone (GH) are pleiotropic, including growth promotion, energy mobilization, gonadal development, appetite, and social behavior. The regulatory network for GH is complex and includes many central and peripheral endocrine factors as well as that from the environment. It is known that GH transgenesis results in increased growth, food intake, and consequent metabolic rates in fishes. However, the manner in which GH transgenesis alters the energetic metabolism in fishes has not been well explored. In order to elucidate these consequences, we examined the effect of GH overexpression on appetite control mechanisms in a transgenic zebrafish (Danio rerio) model. To this, we analyzed feeding behavior and the expression of the main appetite-related genes in two different feeding periods (fed and fasting) in non-transgenic (NT) and transgenic (T) zebrafish as well as glycaemic parameters of them. Our initial results have shown that NT males and females present the same feeding behavior and expression of main appetite-controlling genes; therefore, the data of both sexes were properly grouped. Following grouped data analyses, we compared the same parameters in NT and T animals. Feeding behavior results have shown that T animals eat significantly more and faster than NT siblings. Gene expression results pointed out that gastrointestinal (GT) cholecystokinin has a substantial contribution to the communication between peripheral and central control of food intake. Brain genes expression analyses revealed that T animals have a down-regulation of two strong and opposite peptides related to food intake: the anorexigenic proopiomelanocortin (pomc) and the orexigenic neuropeptide Y (npy). The down-regulation of pomc in T when compared with NT is an expected result, since the decrease in an anorexigenic factor might keep the transgenic fish hungry. The down-regulation of npy seemed to be contradictory at first, but if we consider the GH's capacity to elevate blood glucose, and that NPY is able to respond to humoral factors like glucose, this down-regulation makes sense. In fact, our last experiment showed that transgenics presented elevated blood glucose levels, confirming that npy might responded to this humoral factor. In conclusion, we have shown that GT responds to feeding status without interference of transgenesis, whereas brain responds to GH transgenesis without any effect of treatment. It is clear that transgenic zebrafish eat more and faster, and it seems that it occurs due to pomc down-regulation, since npy might be under regulation of the humoral factor glucose.

Insulin-like growth factor (IGF)-I and IGF binding proteins axis in diabetes mellitus

Increasing evidence suggests an important role of the insulin-like growth factor (IGF)-IGF binding protein (IGFBP) axis in the maintenance of normal glucose and lipid metabolism. Significant changes occur in the local IGF-I-IGFBPs environment in response to the diabetic milieu. A significant reduction of serum IGF-I levels was observed in patients with type 1 diabetes mellitus (T1DM). Inversely, considerably increased serum levels of IGF-I and IGFBP-3 levels were detected in individuals with glucose intolerance including T2DM. Recently, several prospective studies indicated that baseline levels of IGF-I and IGFBPs are associated with the development of diabetes. These findings suggest that disturbances in insulin and IGF-I-IGFBP axis can affect the development of glucose intolerance including diabetes.

Residual β-cell function and the insulin-like growth factor system in Danish children and adolescents with type 1 diabetes

CONTEXT

C-peptide-positive adults with type 1 diabetes (T1D) have higher circulating total and free IGF-1 and lower IGF binding protein 1 (IGFBP-1) than C-peptide-negative patients. Whether this is also the case in children remains unknown.

OBJECTIVE

The objective of the study was to examine the IGF system in children/adolescents with and without residual β-cell function (RBF).

DESIGN AND PATIENTS

This was a cross-sectional study containing 136 prepubertal (hereof 15 RBF positive) and 206 pubertal (hereof 42 RBF positive) children/adolescents with T1D for 3-6 years as well as 40 prepubertal and 30 pubertal healthy controls. RBF was evaluated by meal-stimulated C-peptide.

MAIN OUTCOME MEASURES

Fasting serum levels of bioactive IGF (ie, the ability of serum to activate the IGF-1 receptor in vitro), total IGF-1, total IGF-2, and IGFBP-1 and -3.

RESULTS

Irrespective of pubertal status, patients with T1D showed lower bioactive IGF and total IGF-1, but higher IGFBP-1 as compared with controls (P < .05). When stratified according to RBF status, a positive RBF was associated with normalization of all IGF-related peptides but IGFBP-1 in prepubertal children (P < .05), whereas none of the IGF components were normalized in prepubertal, RBF-negative children. In pubertal children, total IGF-1 and bioactive IGF remained subnormal and IGFBP-1 supranormal, irrespective of RBF status (P < .05).

CONCLUSION

Independent of pubertal status, T1D was associated with an abnormal IGF system. However, a positive RBF status appeared important but only in prepubertal children, in whom all IGF components but IGFBP-1 were normalized. We speculate that the pubertal GH surge induces insulin resistance, which overrides the stimulatory effect that an RBF may exert on the liver-derived IGF system.

The association of soluble IGF2R and IGF2R gene polymorphism with type 2 diabetes

The aim of this study is to investigate the insulin-like growth factor type 2 (IGF2R) gene and circulating soluble IGF2R in relation to type 2 diabetes (T2DM). Six hundred fifty-four subjects without history of diabetes were screened for diabetes by oral glucose tolerance test. In addition, 145 subjects with known diabetes were recruited from a local diabetes clinic. Circulating IGF2R levels were measured by ELISA method; plasma glucose was measured by colorimetric method; insulin levels were determined by chemiluminescent method; IGF2R gene rs416572 was genotyped using real-time PCR. The distributions of IGF2R genotypes were 69.2% CC, 27.8% CT, and 3.0% TT. The C allele was more commonly found in diabetes subjects, with a significant difference (P < 0.01). In the presence of the T allele, circulating IGF2R levels were significantly lower (P < 0.05). There was no significant difference in other potential confounders including age, sex, and BMI. Only circulating IGF2R, age, and BMI were independently associated with the degree of insulin resistance, as assessed by the HOMA model. It was found that age, sex, and BMI were associated with beta cell function. In conclusion, IGF2R gene polymorphism and circulating IGF2R are associated with T2DM.

Short-term effects of NPH insulin, insulin detemir, and insulin glargine on the GH-IGF1-IGFBP axis in patients with type 1 diabetes

OBJECTIVE

Insulin regulates the GH-IGF1 axis. Insulin analogs differ from human insulin in receptor affinity and possibly liver accessibility. Therefore, we compared the GH-IGF1 axis response with human NPH insulin, insulin detemir, and insulin glargine in patients with type 1 diabetes (T1D).

METHODS

A total of 17 patients (seven were women) with T1D (age of 42 (24-63) years (mean and range), BMI of 24.7 (19.5-28.3) kg/m(2), HbA1c of 7.2 (6.3-8.0) % (55 (45-64) mmol/mol), T1D duration of 26 (8-45) years) were studied using a randomized, three-period crossover design. Patients received s.c. injections of equal, individual doses of NPH, detemir, and glargine at 1800 h. Plasma glucose, serum total IGF1, bioactive IGF, IGF-binding protein (IGFBPs), and GH were measured hourly for 14 h post-injection.

RESULTS

When compared with the area under the curve (AUC) following NPH and glargine, detemir resulted in the lowest 6-14 h AUC (mean and range) of IGFBP1 (1518 (1280-1800)) vs 1621 (1367-1922) vs 1020 (860-1210) μg/l×h) and GH (17.1 (14.1-20.6) vs 15.4 (12.7-18.6) vs 10.2 (8.5-12.3) μg/l×h), but in the highest AUC of bioactive IGF (3.8 (3.5-4.2) vs 3.7 (3.4-4.0) vs 4.4 (4.1-4.8) μg/l×h) (all P<0.01). These differences were unrelated to plasma glucose. By contrast, profiles of total IGF1, IGFBP2, and IGFBP3 were comparable.

CONCLUSIONS

Independent of plasma glucose, a single dose of detemir caused larger suppression in serum IGFBP1 than NPH and glargine, whereas bioactive IGF was higher, thereby explaining the lower GH levels. Thus, detemir appears to be more liver specific than NPH insulin and glargine.

Effect of sericin on diabetic hippocampal growth hormone/insulin-like growth factor 1 axis

Previous studies have shown that sericin extracted from silk cocoon significantly reduces blood glucose levels and protects the nervous system against diabetes mellitus. In this study, a rat type 2 diabetes mellitus model was established by intraperitoneal injection of 25 mg/kg streptozotocin for 3 successive days, following which the rats were treated with sericin for 35 days. After treatment, the blood glucose levels of the diabetic rats decreased significantly, the growth hormone level in serum and its expression in the hippocampus decreased significantly, while the insulin-like growth factor-1 level in serum and insulin-like growth factor-1 and growth hormone receptor expression in the hippocampus increased significantly. The experimental findings indicate that sericin improves disorders of the growth hormone/insulin-like growth factor 1 axis to alleviate hippocampal damage in diabetic rats.

[Insulin-like growth factor-II secreting prostate tumour causing severe hypoglycaemi]

The authors present a case of an 82-year-old male patient who presented with frequent hypoglycaemia. Four years prior to the current evaluation the patient had been diagnosed with prostate carcinoma; however, he refused surgical treatment. Initial diagnostic tests indicated organic hypoglycaemia with low serum insulin levels. Insulinoma was excluded and further laboratory tests showed reduced serum insulin-like growth factor-II and normal serum chromogranin A levels as well as normal hypophysis and peripheral hormone values. The authors hypothesised that the severe hypoglycaemia might be the consequence of synthesis and secretion of insulin-like growth factor-II (or its prohormone) by the previously diagnosed prostate tumour. Insulin-like growth factor-II and its prohormone directly increases glucose uptake of the tumour, muscle and adipose tissue, decreases glucose release from the liver and downregulates insulin synthesis due to inhibition of the pancreatic beta cells. The patient required continuous intravenous glucose substitution initially with 5%, subsequently with 20% glucose infusion. Administration of other agents resulted only in temporary improvement. Prostatectomy was again considered but then excluded because of the recurrent hypoglycaemia and the poor general condition of the patient. Hypoglycaemia was finally controlled with glucose and diazoxide therapy, but no improvement in the general condition of the patients was observed and the patient deceased. Immunohistochemistry of the prostate sections showed a carcinoma with strong insulin-like growth factor-II staining, suggesting that insulin-like growth factor-II-secreting prostate tumour caused the severe hypoglycaemia.

Coupling physical exercise with dietary glucose supplement for treating cognitive impairment in schizophrenia: a theoretical model and future directions

AIMS

Metabolic dysregulation may disrupt the complex neuroprotective mechanisms essential for brain health. Recent studies have pointed out the possible aetiological role of metabolic dysregulation in the onset of schizophrenia and the associated cognitive impairment. In this paper, we aimed to generate a theoretical model of how a combination of physical exercise and dietary glucose supplement may help to alleviate cognitive impairment in schizophrenia.

METHODS

Literature on metabolic dysregulation, especially insulin resistance, in relation to the onset of schizophrenia and the associated cognitive impairment is reviewed. The cognitive enhancement effects of physical exercise and dietary glucose supplement are then summarised. Finally, we propose a theoretical model based on the concerted effects of physical exercise and glucose supplement.

RESULTS

In general, the joint action of physical exercise and dietary glucose supplement could up-regulate glucose and insulin transport into the brain, as well as augmenting the release of insulin growth factor-1 and brain-derived neurotrophic factor. Physical exercise and glucose supplement could enhance energy supply and neuroplasticity in brain, subsequently leading to potential cognitive enhancement in schizophrenia. However, glucose supplement is not suitable for patients with abnormal metabolic profile.

CONCLUSIONS

The combination of physical exercise and glucose supplement has potential therapeutic values in treating cognitive impairment in schizophrenia. Further research is necessary to investigate the optimal patterns of exercise and doses of glucose for treating cognitive impairment in schizophrenia.

Relationships between IGF-1, schizophrenia, and treatment of metabolic syndrome

OBJECTIVES

The use of atypical antipsychotic drugs in patients with psychiatric illness may result in dyslipidemia, hypertension, glucose intolerance, and abdominal obesity, which are together referred to as metabolic syndrome (MS). To investigate any correlations among insulin-like growth factor-1 (IGF-1), schizophrenia, and MS, we examined the metabolic profiles of patients with schizophrenia taking atypical antipsychotics.

DESIGN

Patients with schizophrenia, their siblings, and controls participated in this study (N=50 in each group). The Structured Clinical Interview for DSM-IV Axis 1 Disorders (SCID I) and the Brief Psychiatric Rating Scale (BPRS) were administered to patients, and SCID I was administered to patients' siblings. We drew blood to measure IGF-1 levels and to determine the metabolic profiles of all participants; we also conducted anthropometric measurements.

RESULTS

There were no significant differences in IGF-1 levels between groups. By comparing IGF-1 levels with MS-related parameters, we found that IGF-1 levels were negatively correlated with triglyceride levels in the control group, and positively correlated with HDL levels in the patient group (Pearson's correlation: r=-0.291, P=0.04, and r=0.328, P=0.02, respectively). Compared to their siblings, patients with schizophrenia had a significantly different body mass index, waist circumference, and insulin resistance, and showed a trend toward a difference in glucose levels (ANOVA: P=0.004, P<0.0001, P=0.004, P=0.072, respectively).

CONCLUSION

A correlation between IGF-1 and MS may significantly influence future therapeutic strategies for MS. In order to determine the role of IGF-1 in schizophrenia, comprehensive longitudinal studies with first-episode drug-naive patients are needed.

Effects of human insulin and insulin aspart preparations on levels of IGF-I, IGFBPs and IGF bioactivity in patients with type 1 diabetes

BACKGROUND

Insulin aspart (IAsp) and its biphasic preparations BIAsp50 and BIAsp70 (containing 50% and 70% IAsp, respectively) have distinct glucose-lowering properties as compared to human insulin (HI). We investigated whether this affected the circulating IGF-system which depends on the hepatic insulin exposure.

METHODS

In a randomized, four-period crossover study, 19 patients with type 1 diabetes received identical doses (0.2 U/kg sc) of IAsp, BIAsp70, BIAsp50 and HI together with a standardized meal. Serum total IGF-I and IGFBP-1 to -3 were measured by immunoassays for nine hours post-prandially. Bioactive IGF was determined by an in-house, cell-based IGF-I receptor kinase activation (KIRA) assay.

RESULTS

Despite marked differences in peripheral insulin concentrations and plasma glucose, the four insulin preparations resulted in parallel decreases in IGFBP-1 levels during the first 3 hours, and parallel increases during the last part of the study (3-9 hours). Thus, only minor significances were seen. Insulin aspart and human insulin resulted in a lower area under the curve (AUC) during the first 3 hours as compared to BIAsp70 (p = 0.009), and overall, human insulin resulted in a lower IGFBP-1 AUC than BIAsp70 (p = 0.025). Nevertheless, responses and AUCs of bioactive IGF were similar for all four insulin preparations. Changes in levels of bioactive IGF were inversely correlated to those of IGFBP-1, increasing during the first 3 hours, whereafter levels declined (-0.83 ≤ r ≤ -0.30; all p-values <0.05).Total IGF-I and IGFBP-3 remained stable during the 9 hours, whereas IGFBP-2 changed opposite of IGFBP-1, increasing after 3-4 hours whereafter levels gradually declined. The four insulin preparations resulted in similar profiles and AUCs of total IGF-I, IGFBP-2 and IGFBP-3.

CONCLUSIONS

Despite distinct glucose-lowering properties, the tested insulin preparations had similar effects on IGF-I concentration and IGF bioactivity, IGFBP-2 and IGFBP-3 as compared to HI; only small differences in IGFBP-1 were seen and they did not affect bioactive IGF. Thus, insulin aspart containing preparation behaves as HI in regards to the circulating IGF-system. However, bioactive IGF appeared to be more sensitive to insulin exposure than total IGF-I. The physiological significance of this finding remains to be determined.

TRIAL REGISTRATION

NCT00888732.