Insulin resistance is the main determinant of impaired glucose tolerance in patients with liver cirrhosis

To clarify the pathogenesis of impaired glucose tolerance in patients with cirrhosis, several factors possibly affecting carbohydrate metabolism were studied in 12 cirrhotic patients with different blood glucose responses to an oral glucose tolerance test. Glucose levels, 120 min after the load, were inversely and significantly related to insulin sensitivity, measured by means of the euglycemic glucose clamp technique (r=–0.746). Basal and glucose-induced insulin secretion (insulin and C-peptide levels) only slightly correlated with glucose tolerance, which was not related to functional liver cell mass (galactose elimination), portal-systemic shunting (degree of varices at endoscopy), or maximal glucose-independent insulin secretion (peak C-peptide levels after a glucagon test). Multiple regression analysis identified insulin sensitivity and liver cell mass as the independent variables able to explain most of the variance of 120-min blood glucose (about 84%), and both of them contributed considerably to the regression. While reduced insulin sensitivity is probably the main cause of impaired glucose tolerance, the reduced hepatocellular mass only appears to modulate the degree, and therefore the clinical relevance, of this defect.Supported by a Grant from Ministero della Pubblica Istruzione, Rome, 1983.This work was presented at the III Italian Week on Digestive Diseases (SIMAD III), Bari, Italy, June 27–July 1, 1983 and published in abstract form (Ital J Gastroenterol 16:143, 1984).     

Spontaneous porto-systemic shunts in liver cirrhosis: Clinical and therapeutical aspects

Spontaneous porto-systemic shunts(SPSS) are frequent in liver cirrhosis and their prevalence increases as liver function deteriorates, probably as a consequence of worsening portal hypertension, but without achieving an effective protection against cirrhosis' complications. Several types of SPSS have been described in the literature, each one associated with different clinical manifestations. In particular,recurrent or persistent hepatic encephalopathy is more frequent in patients with splenorenal shunt, while the presence of gastric varices and consequently the incidence of variceal bleeding is more common in gastrorenal shunt. In the advanced stage, the presence of large SPSS can lead to the so called"portosystemic shunt syndrome", characterized by a progressive deterioration of hepatic function, hepatic encephalopathy and, sometimes, portal vein thrombosis. The detection of SPSS in patients with liver cirrhosis is recommended in order to prevent or treat recurrent hepatic encephalopathy or variceal bleeding.     

Large spleno-caval shunt not accompanied by cirrhosis or encephalopathy

A 40-year-old man with a large spleno-caval shunt through the azygos vein is described. This was considered a rare case, because the patient had no accompanying advanced liver disease, or episodes of hepatic encephalopathy. During checks after abnormal liver function test results, a shunt vessel was detected incidentally by ultrasonography. Computed tomography, magnetic resonance imaging, and angiography demonstrated that it was a large shunt between the splenic vein and superior vena cava through the coronary and azygos veins. The patient was a hepatitis B virus carrier and was positive for anti-HBe, and had a history of heavy drinking. However, on laparoscopic examination, the liver was not cirrhotic and the biopsy revealed only mild chronic hepatitis without bridging fibrosis. There were no esophageal varices or hepatosplenomegaly. On hemodynamic evaluation, the wedge hepatic vein pressure was slightly elevated and hepatic blood flow was reduced to half the normal value. Despite the large portal-systemic shunt, the patient had no history or signs of hepatic encephalopathy. The clinical features of this rare case are discussed.     

Insulin resistance and liver injury in hepatitis C is not associated with virus-specific changes in adipocytokines

The role of tumor necrosis factor alpha, interleukin 6, leptin, and adiponectin in the pathogenesis of hepatitis C virus (HCV)-associated insulin resistance (IR) remains controversial. We tested the hypothesis that these adipocytokines contribute to chronic HCV-associated IR and liver injury by first comparing their serum levels and homeostasis model assessment of insulin resistance (HOMA-IR) in 154 untreated, non-diabetic, HCV-infected male subjects with fibrosis stage 0-2, to that in 75 healthy volunteers matched for age, body mass index (BMI), and waist-hip ratio (WHR). We next examined whether the adipocytokine levels were associated with the extent of hepatic steatosis, portal/periportal inflammation and fibrosis in our total cohort of 240 HCV-infected male subjects. Significantly higher levels of HOMA-IR (2.12 versus 1.63, P = 0.01), TNFalpha (1.28 versus 0.60 pg/ml, P < 0.001) and IL6 (2.42 versus 1.15 pg/ml, P = 0.001) were noted in the HCV cohort compared with healthy controls respectively, but there were no significant differences in leptin and adiponectin concentrations. By multiple linear regression, independent predictors of HOMA-IR included the body mass index, and the serum levels of leptin (positive correlation) and adiponectin (negative correlation), but not that of TNFalpha and IL6. Only TNFalpha levels were correlated with the extent of histological injury (portal/periportal inflammation, P = 0.02). CONCLUSION: Whereas leptin and adiponectin contribute to IR, none of the adipocytokines accounted for the elevated IR in HCV-infected subjects. The adipocytokines were not associated with histological features of chronic HCV infection except for TNFalpha which correlated with portal/periportal inflammation. HCV-associated IR is most likely an adipocytokine-independent effect of the virus to modulate insulin sensitivity.     

Insulin resistance is not associated with liver fibrosis progression in HIV/hepatitis C virus-coinfected patients

Insulin resistance (IR) is a common condition in chronic hepatitis C. Recent studies have reported that IR is associated with liver fibrosis progression in these patients. However, there is no information available on this issue in human immunodeficiency virus (HIV)/hepatitis C virus (HCV)-coinfected patients. For these reasons, we investigate the relationship between IR and liver fibrosis in patients with HIV and HCV infections. This was a cross-sectional study where patients from an Infectious Diseases Unit with HIV/HCV coinfection who underwent a liver biopsy, with available frozen sera samples at the time of biopsy and a known or estimated date of infection were included. IR was determined by the homeostasis model assessment (HOMA-IR) method. The relationship between histological findings and several variables, including HOMA-IR values, was examined. Seventy-nine patients fulfilled the inclusion criteria. Age at HCV infection >21 years was the only variable independently associated with advanced liver fibrosis (stages F3 and F4) [adjusted odds ratio (AOR) 4.15; 95% confidence interval (CI) 1.5-11.3]. The variables associated with a fibrosis progression rate above the median were age at HCV infection >21 years (AOR 6.41; 95% CI 2.16-27.96) and previous exposure to nevirapine (AOR 8.9; 95% CI 2.01-39.36). There was no association between HOMA-IR values and the presence of advanced fibrosis or a faster fibrosis progression. Thus IR is not associated with liver damage or fibrosis progression in HIV/HCV-coinfected individuals.     

Insulin resistance is not associated with myocardial steatosis in women

Aims/hypothesis  

Insulin resistance, an independent risk-factor for cardiovascular disease, precedes type 2 diabetes and is associated with ectopic lipid accumulation in skeletal muscle and liver. Recent evidence indicates that cardiac steatosis plays a central role in the development of diabetic cardiomyopathy. However, it is not known whether insulin resistance as such in the absence of type 2 diabetes is associated with heart steatosis and/or impaired function. We therefore assessed myocardial steatosis and myocardial function in a sample of women with normal insulin sensitivity, insulin resistance, impaired glucose tolerance (IGT) and type 2 diabetes.     

Insulin resistance of late pregnancy does not include the liver

Hyperinsulinemia was required to preserve normal intravenous glucose tolerance in late pregnancy in the rat (18 to 21 days' gestation). To evaluate the site and mechanism of this insulin resistance, insulin binding and action were measured in hepatocytes freshly isolated from control and gravid animals. As expected, glucose concentrations were lower, insulin levels were higher, and hepatocyte size increased in the pregnant animals. Insulin binding was similar in liver cells from the two groups. No difference was found in sensitivity or responsiveness of insulin-stimulated net 14C-glucose incorporation into glycogen in the hepatocytes from the control and gravid rats. These results suggest that the well-documented, but ill-defined, insulin antagonism of late pregnancy does not include the liver and is a postreceptor defect, most likely residing in muscle tissue.     

Insulin and glucagon levels in liver cirrhosis

Alterations in insulin and glucagon levels might account for the plasma amino acid imbalance of cirrhotics. In order to verify this hypothesis we evaluated basal insulin, glucagon, branched-chain amino acids, aromatic amino acids, and free tryptophan in 13 controls and 37 cirrhotics divided on the basis of their mental state; in 4 patients the hormonal and amino acid patterns were sequentially studied during various stages of encephalopathy. Glucagon is high in cirrhotics and progressively increases with the worsening of the mental state. Free tryptophan and aromatic amino acids show a similar behavior and significantly correlate with glucagon levels (r = 0.67 and r = 0.81, respectively). On the other hand insulin levels, which are high in cirrhotics without encephalopathy, fall in the presence of deep coma. Insulin did not correlate with any of the plasma amino acids considered. Our data suggest that the catabolic state associated with increased glucagon levels may account for some of the alterations in the plasma amino acid profiles of cirrhotics. Portal-systemic shunting does not seem to be the common cause of both hyperglucagonemia and hyperaminoacidemia. Decreased branched-chain amino acid levels may be related to factors different from those involved in the alterations of carbohydrate homeostasis.     

Glucose tolerance after portacaval shunt in liver cirrhosis

The liver plays a key role in glucose homeostasis and insulin metabolism. Altered glucose and insulin levels in peripheral blood are common findings in chronic liver disease. The aim of the present study was to investigate the effect of surgical portosystemic shunt on plasma glucose and insulin responses to glucose administration in a group of cirrhotic patients. For this purpose 10 cirrhotic subjects (8 males and 2 females) aged 42 to 65 years underwent an oral glucose tolerance test (OGTT, 75 g), and an intravenous glucose tolerance test (IVGTT, 0.33 g/kg) before and after undergoing a side-to side portocaval anastomosis (PCS). 6 noncirrhotic, nondiabetic patients matched for sex, age and body weight who underwent abdominal vascular surgery served as controls. In cirrhotic subjects, the PCS resulted in: increased plasma glucose and insulin levels during OGTT; decreased C-peptide level during OGTT; unmodified plasma glucose and insulin concentrations during IVGTT. In control subjects the abdominal surgery did not affect plasma glucose and insulin responses to oral or intravenous glucose loads. These results suggest that in cirrhotic subjects surgical portocaval shunt results in: deterioration of oral but not intravenous glucose tolerance, due to an escape of ingested glucose from the liver; increased peripheral insulin response to oral glucose administration as a consequence of reduction in hepatic removal of the hormone; and decreased pancreatic response to oral glucose due possibly to a greater feed back inhibition of beta-cell. These events seem to be a consequence of the shunt per se and not of a deterioration of hepatocellular function.     

Insulin resistance in liver diseases

Coexistence of hyperinsulinemia and normal or impaired carbohydrate tolerance indicates insulin resistance which is frequently observed in patients with liver diseases such as liver cirrhosis, fatty liver, acute and chronic hepatitis and idiopathic haemochromatosis. Insulin resistance in liver diseases can be due to circulating insulin antagonists or a target tissue defect in insulin action, either due to changes in the state of the insulin receptor or due to a postreceptor defect, that means any abnormality in the insulin action sequence following the initial binding step. High insulin levels in liver diseases are caused by diminished degradation of insulin by the liver whereas hypersecretion only plays a minor role under basal conditions. High levels of glucagon, free fatty acids and growth hormone are well known in liver diseases but until now there is no evidence of the pathogenetic importance of these factors. Conflicting results on insulin binding, methodological criticism on binding data and the question whether or not diminished insulin binding on peripheral blood cells plays any physiological role make it unlikely that studies on insulin receptors of peripheral blood cells contribute to the revelation of insulin resistance in liver diseases. The clamp technique allows to quantify the sensitivity of the body to exogenous insulin. The results on liver cirrhosis in connection with studies on glucose metabolism show that under basal conditions insulin insensitivity is due to peripheral resistance (primarily muscle) according to a postreceptor defect. Finally the causes of insulin resistance in liver diseases are still not known.     

Insulin resistance but not inflammation is associated with gestational hypertension

Hypertensive disorders of pregnancy, including gestational hypertension and preeclampsia, are leading causes of pregnancy-associated morbidity. Although insulin resistance and inflammation contribute to preeclampsia, prospective data regarding mechanisms of gestational hypertension are sparse. We conducted a prospective, nested case-control study to test the hypotheses that insulin resistance, marked by reduced sex hormone-binding globulin (SHBG) levels, and inflammation, marked by increased C-reactive protein levels, are similarly associated with gestational hypertension. We measured first-trimester C-reactive protein and SHBG levels in 51 women who subsequently developed gestational hypertension and 102 randomly selected normotensive pregnant controls. Compared with controls, first-trimester SHBG levels were significantly reduced among women who later developed gestational hypertension (176+/-73 versus 203+/-79 nmol/L; P=0.03), but there was no difference in C-reactive protein levels. There was statistically significant interaction among nulliparity, first-trimester SHBG levels, and risk of gestational hypertension, such that increasing SHBG levels were associated with significantly reduced risk of gestational hypertension among nulliparous women (odds ratio, 0.64 per 50-nmol/L increase; 95% confidence interval, 0.46, 0.90; P<0.01) but not among multiparous women. This association remained significant after adjusting for potential confounders (odds ratio, 0.55; 95% confidence interval, 0.31, 0.98; P=0.04). We conclude that insulin resistance, but not inflammation, is an independent risk factor for gestational hypertension among nulliparous women. Furthermore, important mechanistic differences exist in the pathogenesis of gestational hypertension comparing nulliparous and multiparous women.     

Insulin resistance and insulin receptors in hepatic cirrhosis

To explore the influence of extrahepatic factors in the pathogenesis of insulin resistance in hepatic cirrhosis, we studied 125I-insulin binding to erythrocytes and monocytes of 14 clinically stable cirrhotic individuals and compared the results with a normal control group. All patients had fasting normoglycemia at the time of the study but abnormal glucose tolerance was detected in 7 of 9 cirrhotic patients after an oral glucose load. Seven patients (group N) had normal fasting serum insulin levels, and 7 patients (group H) manifested fasting hyperinsulinemia. However, all patients had elevated insulin levels after oral glucose. Insulin binding to erythrocytes was significantly decreased in both cirrhotic subgroups; monocyte studies in 5 hyperinsulinemic patients revealed a similar decrease in binding. Scatchard analysis in monocytes suggests that this decreased binding is secondary to a decrease in the receptor number per cell. No correlation between insulin binding and fasting plasma insulin, glucagon, or growth hormone levels was seen. Sera from 4 patients were examined for the presence of a non-specific inhibitor of insulin binding, but no evidence for such a factor was found. We conclude that the decrease in insulin binding is mediated in the monocyte by a reduction of receptor concentration; in the erythrocyte the mechanism for decreased binding could not be clearly delineated. The insulin resistance seen in cirrhosis may result in part from decreased binding of insulin to target tissues; an additional postreceptor defect cannot be excluded in hyperinsulinemic individuals.     

Hypogonadism is not related to the etiology of liver cirrhosis

We investigated the clinical and laboratory findings of hypogonadism and feminization in male patients with viral or alcoholic cirrhosis to determine whether chronic liver disease plays a primary role in the development of sexual dysfunction and hormonal changes. Two groups of male patients with liver cirrhosis (23 alcoholic, 33 viral) age-and Child's gradematched, and 20 age-matched healthy men, as a control group, were included in this study. Clinical signs of hypogonadism and feminization were examined in the cirrhotic patients. Follicle-stimulating hormone, luteinizing hormone, prolactin, testosterone, free testosterone, estradiol, androstenedione, dehydroepiandrosterone sulfate, and sex hormone-binding globulin were estimated in all groups. Seminal fluid was also analyzed in 7 alcoholic and 15 viral cirrhotics. Serum levels of estradiol, androstenedione, and sex hormone-binding globulin were significantly higher, and free testosterone and dehydroepiandrosterone sulfate levels were significantly lower in both groups of cirrhotics compared with the control group. Child's C patients in both groups of cirrhotics were found to have higher estradiol and lower free testosterone levels than child's A and B patients. Alcoholic and viral cirrhotics had markedly reduced sperm motility and density. The differences between alcoholic and viral cirrhotic patients in the clinical signs of hypogonadism, serum levels of sex steroids, and the results of seminal fluid analysis were not statistically significant. These findings suggest that liver cirrhosis per se, independent of etiology, causes hypogonadism and feminization, and that the degree of hypogonadism and feminization correlates well with the severity of liver failure.     

Insulin resistance is not coupled with defective insulin secretion in primary hyperparathyroidism

Aims An increased frequency of both impaired glucose tolerance and Type 2 diabetes mellitus (DM) has been reported in primary hyperparathyroidism (pHPT), thus we sought to investigate insulin sensitivity and insulin secretion in a large series of pHPT patients. Subjects and methods One hundred and twenty‐two consecutive pHPT patients without known DM were investigated [age (mean ± sd ) 59.3 ± 13.6 years, body mass index (BMI) 25.7 ± 4.2 kg/m²; serum calcium 2.8 ± 0.25 mmol/l; PTH 203.2 ± 145.4 ng/l]. Sixty‐one control subjects were matched, according to the degree of glucose tolerance, in a 2 : 1 patient:control ratio. Fasting‐ and oral glucose tolerance test‐derived estimates of insulin sensitivity and secretion were determined by means of the quantitative insulin sensitivity check index (QUICKI) and the insulin sensitivity index (ISI) composite. Results Both the QUICKI and ISI composite were lower in pHPT patients than control subjects (P < 0.03 and P < 0.05, respectively) after adjusting for age, systolic blood pressure and BMI. Conversely, all insulin secretion estimates were significantly increased in pHPT patients than in control subjects (P < 0.04 and P < 0.03, respectively) and after adjusting for age, systolic blood pressure and BMI. Log serum calcium levels were negatively associated with the QUICKI and log ISI composite (R = ?0.30, P = 0.001; R = ?0.23, P = 0.020, respectively) in pHPT patients. Serum calcium levels significantly and independently contributed to impaired insulin sensitivity in multivariate analysis (QUICKI as dependent variable: β = ?0.31, P = 0.004, R² = 0.15; log ISI composite as dependent variable: β = ?0.29, P = 0.005, R² = 0.16). Conclusions Our study confirms a reduction in both basal and stimulated insulin sensitivity in primary hyperparathyroidism, in spite of increased insulin secretion. Moreover, our data show for the first time a significant relationship between hypercalcaemia and insulin sensitivity in this condition.     

肝硬化患者肿瘤坏死因子水平变化与胰岛素抵抗的关系

为探讨肝硬化患者血清肿瘤坏死因子－α（TNF-α）水平变化及与胰岛素抵抗(IR)的关系。有用氧化酶法、放免法和酶联免疫法分别测定23例肝硬化患者（A组）、21例健康人（B组）和空腹血糖（FBG）、空腹胰岛素（FINS）及血清TNF－α值，并计算胰岛素敏感指数（ISI).A组FINS、TNF－α水平较B组显著增高，而ISI较B组显著降低。相关分析发现，TNF－α与ISI呈显著负相关，而与FINS呈显著正相关。肝硬化患者TNF－α水平增高，导致胰岛素抵抗产生，可能是肝硬化患者糖代谢紊乱的 重要原因之一。