Liver disease, carbohydrate metabolism and diabetes

Glucose transporter 4: Insulin response mastermind, glycolysis catalyst and treatment direction for cancer progression

The glucose transporter family (GLUT) consists of fourteen members. It is responsible for glucose homeostasis and glucose transport from the extracellular space to the cell cytoplasm to further cascade catalysis. GLUT proteins are encoded by the solute carrier family 2 (SLC2) genes and are members of the major facilitator superfamily of membrane transporters. Moreover, different GLUTs also have their transporter kinetics and distribution, so each GLUT member has its uniqueness and importance to play essential roles in human physiology. Evidence from many studies in the field of diabetes showed that GLUT4 travels between the plasma membrane and intracellular vesicles (GLUT4-storage vesicles, GSVs) and that the PI3K/Akt pathway regulates this activity in an insulin-dependent manner or by the AMPK pathway in response to muscle contraction. Moreover, some published results also pointed out that GLUT4 mediates insulin-dependent glucose uptake. Thus, dysfunction of GLUT4 can induce insulin resistance, metabolic reprogramming in diverse chronic diseases, inflammation, and cancer. In addition to the relationship between GLUT4 and insulin response, recent studies also referred to the potential upstream transcription factors that can bind to the promoter region of GLUT4 to regulating downstream signals. Combined all of the evidence, we conclude that GLUT4 has shown valuable unknown functions and is of clinical significance in cancers, which deserves our in-depth discussion and design compounds by structure basis to achieve therapeutic effects. Thus, we intend to write up a most updated review manuscript to include the most recent and critical research findings elucidating how and why GLUT4 plays an essential role in carcinogenesis, which may have broad interests and impacts on this field.

Diagnosis and Clinical Implications of Diabetes in Liver Cirrhosis: A Focus on the Oral Glucose Tolerance Test

The liver and skeletal muscles are responsible for maintaining glucose metabolism. As chronic liver disease progresses to cirrhosis, the loss of liver function is exacerbated and leads to the deterioration of skeletal muscle. Consequently, impaired glucose tolerance (IGT) and insulin resistance are often observed in patients with liver cirrhosis. Early stage cirrhosis with hepatogenous diabetes is characterized by marked postprandial hyperglycemia and hyperinsulinemia. Generally, it is possible to underestimate IGT when using either the conventional fasting plasma glucose (FPG) criterion or hemoglobin A1c (HbA1c) levels despite their status as the gold standard for diagnosing diabetes. The number of cirrhotic patients with diabetes tends to be underestimated because many of these patients show lower FPG levels or HbA1c, which masks their IGT. In such cases, the oral glucose tolerance test is recommended to evaluate patients with suspected postprandial hyperglycemia who present with a normal FPG. Moreover, in addition to the Child-Pugh score, the early detection of diabetes may be a useful prognostic marker for patients with liver cirrhosis.

Effect of liver transplantation on glucose levels in patients with prediabetes or type 2 diabetes

BACKGROUND

Liver transplantation (LT) may induce the occurrence of diabetes mellitus. It can be speculated, however, that the LT may have a beneficial effect on glucose metabolism. We therefore conducted a study to examine the changing trends in blood glucose levels before and after LT in patients with prediabetes or type 2 diabetes.

METHODS

In this observational study, we enrolled 47 patients (38 prediabetes and 9 diabetes) who underwent LT. We compared the blood glucose levels between the pre-transplantation (24 months) and the post-transplantation (36 months) periods and analyzed the diverse factors affecting glucose levels.

RESULTS

The glucose regulation worsened and insulin dose increased in patients with diabetes, which was notably seen during the steroid maintenance period. Following steroid withdrawal, however, there was a decrease in the insulin dose in 55.6% of the patients, and 33.3% of the patients converted from insulin to oral agents. Of the patients with prediabetes, 55.3% developed new-onset diabetes after transplantation (NODAT). However, 18.4% achieved a recovery of glucose levels to normal range. Of the 21 NODAT patients, 52.4% achieved a recovery of glucose level to the prediabetes range after steroid withdrawal. There was a significant correlation between the old age and the persistence of NODAT (P < .05).

CONCLUSIONS

LT may have a diverse effect on glycemia, which may lead to changes in glucose control methods. Therefore, glucose metabolism after LT may need to be differentiated by the underlying glucose disturbance status and the time after LT with or without steroid maintenance period.

Insulin sensitivity and body composition in cirrhosis: changes after TIPS

Insertion of a transjugular intrahepatic porto-systemic shunt (TIPS) increases body cell mass (BCM) in patients with liver cirrhosis. The responsible mechanism is unidentified, but may involve changes in insulin sensitivity and glucose metabolism. Eleven patients with liver cirrhosis were examined before and 6 mo after a TIPS procedure with bioimpedance analyses, 2-h oral glucose tolerance tests, and two-step hyperinsulinemic euglycemic clamp with tracer-determined endogenous glucose production. After TIPS, BCM increased by 4.8 kg [confidence interval (CI): 2.7-7.3]. Fasting (f)-insulin increased from 123 +/- 81 to 193 +/- 124 pmol/l (P = 0.03), whereas f-glucose was unchanged (6.0 +/- 0.8 vs. 6.2 +/- 1.0 mmol/l). Glucose and insulin oral glucose tolerance test area under the curve increased by 14% (CI: 7-22%) and 53% (CI: 14-90%), respectively, P < 0.05. The C-peptide-to-insulin ratio decreased by 21% (CI: 8-35%, P = 0.01). Insulin sensitivity based on glucose infusion rate (4.69 +/- 1.82 vs. 4.85 +/- 2.37 mg.kg(-1).min(-1)) and glucose tracer-based rate of disappearance were unchanged (5.01 +/- 1.61 vs. 4.97 +/- 2.13 mg.kg(-1).min(-1)). Despite a further increase in peripheral hyperinsulinemia, f-endogenous glucose production did not change between study days (2.01 +/- 0.42 vs. 2.42 +/- 0.58 mg.kg(-1).min(-1)) and was suppressed equally by insulin (1.1 +/- 0.1 vs. 1.0 +/- 0.1 mg.kg(-1).min(-1)). Insulin clearance, growth hormone, cortisol, and glucagon levels were unchanged. BCM improvement did not correlate with the measured variables. After TIPS, BCM rose, despite enhanced hyperinsulinemia and aggravated glucose intolerance, but unchanged peripheral and hepatic insulin sensitivity. This apparent discrepancy may be ascribed to shunt-related decreased insulin exposure to the liver cells. However, the anabolic effect of TIPS seems not to be related to improvements in insulin sensitivity and remains mechanistically unexplained.

Plasma levels of PBEF/Nampt/visfatin are decreased in patients with liver cirrhosis

Liver cirrhosis is a catabolic disease associated with a high incidence of insulin resistance and diabetes mellitus. Pre-B cell colony-enhancing factor/ nicotinamide phosphoribosyltransferase/visfatin has been characterized as a novel adipokine with a potential role in glucose metabolism and nicotinamide dinucleotide (NAD) generation. We studied plasma levels and metabolic relevance of visfatin in 19 patients with cirrhosis and 19 body mass index-, age-, and sex-matched controls. In addition, hepatic mRNA expression was assessed by qPCR in livers of seven patients with cirrhosis and four controls. Circulating visfatin was 78% lower in cirrhotics (P < 0.001) and decreased with worsening of the clinical stage of liver disease. Hepatic visfatin secretion decreased with clinical stage (P < 0.05) and reduced liver function (P = 0.01). Consistent with these data, hepatic visfatin mRNA expression was significantly lower in cirrhotic livers (P < 0.05). Circulating visfatin in cirrhosis was correlated with body cell mass (r = 0.72, P < 0.01) as well as with body fat mass (r = 0.53, P < 0.05) but not with plasma glucose, insulin, the degree of insulin resistance, or whole body glucose oxidation rates. Higher visfatin levels were associated with higher hepatic glucose production (r = 0.53, P < 0.05) and also with a higher arterial ketone body ratio (KBR) (r = 0.48, P < 0.05), an indicator of increased hepatic NAD generation. In conclusion, circulating visfatin levels are significantly decreased in liver cirrhosis, presumably attributable to decreased hepatic expression and production. Plasma visfatin in cirrhosis is not associated with insulin resistance but correlates with hepatic glucose production and the arterial KBR, indicating a potential link between the NAD-generating properties of visfatin and metabolism.

Muscle GLUT4 in cirrhosis

BACKGROUND/AIMS

The insulin-dependent glucose transporter GLUT4 mediates 50-80% of whole body glucose uptake, but its relation to the frequent glucose intolerance in patients with liver cirrhosis is unknown.

METHODS

Thirty patients and seven healthy controls underwent a 2-h oral glucose tolerance test and later a muscle biopsy. Levels of GLUT4 total protein and mRNA content were determined in muscle biopsies by polyclonal antibody labelling and RT-PCR, respectively.

RESULTS

GLUT4 protein content in the cirrhosis group was not different from that of the controls, but at variance with the control subjects it correlated closely with measures of glucose tolerance (R(2)=0.45; p=0.003). GLUT4 mRNA of the patients with cirrhosis was reduced to 56% of control value (95% ci: 27-86%; p=0.015) and was inversely related to the level of basal hyper-insulinemia (R(2)=0.39; p=0.004).

CONCLUSIONS

In cirrhosis GLUT4 protein content was quantitatively intact, while limiting glucose tolerance. This indicates loss of redundancy of the major glucose transport system, possibly related to the markedly decreased expression of its gene. Hyper-insulinemia may be a primary event. Our findings implicate the muscular GLUT4 system in the glucose intolerance of liver cirrhosis by a mechanism different from that in diabetes.

Monitoring Hepatic and Renal Function

Liver disease represents a serious risk factor for patients requiring anesthesia and surgery. Even subclinical liver disease increases perioperative morbidity and mortality. Perioperative renal dysfunction and failure have similar implications. Thus, detection of early hepatic and renal dysfunction and monitoring of their progress is essential. This article discusses methods for monitoring hepatic and renal function in patients who have high risk for liver or renal injury in the perioperative period.

Elevated resistin levels in cirrhosis are associated with the proinflammatory state and altered hepatic glucose metabolism but not with insulin resistance

The adipokine resistin has been implicated in obesity and insulin resistance. Liver cirrhosis is associated with decreased body fat mass and insulin resistance. We determined plasma resistin levels in 57 patients with cirrhosis, 13 after liver transplantation, and 30 controls and correlated these with hemodynamic as well as hepatic and systemic metabolic parameters. Patients with cirrhosis had, dependent on the clinical stage, an overall 86% increase in resistin levels (P < 0.001) with hepatic venous resistin being higher than arterial levels (P < 0.001). Circulating resistin was significantly correlated with plasma TNF-alpha levels (r = 0.62, P < 0.001). No correlation was observed between resistin and hepatic hemodynamics, body fat mass, systemic energy metabolism, and the degree of insulin resistance. However, plasma resistin in cirrhosis was negatively associated with hepatic glucose production (r = -0.47, P < 0.01) and positively with circulating free fatty acids (FFA; r = 0.40, P < 0.01) and ketone bodies (r = 0.48, P < 0.001) as well as hepatic ketone body production (r = 0.40, P < 0.01). After liver transplantation, plasma resistin levels remained unchanged, whereas insulin resistance was significantly improved (P < 0.01). These data provide novel insights into the role of resistin in the pathophysiological background of a catabolic disease in humans and also indicate that resistin inhibition may not represent a suitable therapeutic strategy for the treatment of insulin resistance and diabetes in patients with liver cirrhosis.

Effect of late evening snack with rice ball on energy metabolism in liver cirrhosis

OBJECTIVE

This study investigates the effects of a late evening snack (LES), of 200 kcal of rice ball, on energy metabolism in cirrhotic patients. Impaired nutritional metabolism has been associated with cirrhosis, and frequent intake of small meals may prevent early-onset starvation, and maintain nourishment in these patients.

SUBJECTS

Twenty-one cirrhotic patients and 26 control subjects (Control) were recruited for this study. Patients were subsequently treated by LES (LC-LES) and by a non-LES regimen (LC-NLES).

METHOD

Resting energy expenditure and respiratory quotient (RQ) were assessed by indirect calorimetry at 0830, 1130 and 1430. Blood glucose and non-esterified fatty acids (NEFA) were measured just before the energy metabolism measurements. The regular diet included three major meals and LES, at 0900, 1200, 1800 and 2100, respectively. The Control and LC-NLES groups received only the major meals, whereas the LC-LES group received three meals plus 200 kcal LES for 7 days. There was no difference in the total energy intake among Control, LC-NLES and LC-LES groups.

RESULTS

Respiratory quotient in LC-NLES was significantly lower than that of Control at 0830. Respiratory quotient value in LC-LES significantly elevated from that in LC-NLES. The RQ values did not differ among Control, LC-NLES and LC-LES at 2 h after the meal (1130 and 1430). Non-esterified fatty acids in LC-LES were lower than that in LC-NLES after overnight fasting.

CONCLUSIONS

The ingestion of a 200 kcal rice ball LES can improve the nutritional metabolism in cirrhotic patients.

Oral glucose tolerance test predicts prognosis of patients with liver cirrhosis

OBJECTIVE

The aim of this study was to evaluate whether oral glucose tolerance test (OGTT) was useful in evaluating the prognosis of patients with liver cirrhosis.

METHODS

Fifty-six patients with liver cirrhosis were enrolled in a prospective cohort study. In all cases, glucose tolerance was diagnosed by a 75-g OGTT according to World Health Organization (WHO) criteria. The relationship of clinical variables to the cirrhosis-related prognosis was investigated using univariate and multivariate regression models.

RESULTS

Diabetes mellitus (DM) was diagnosed in 21 subjects (38%), impaired glucose tolerance (IGT) in 13 subjects (23%), and normal glucose tolerance (NGT) in 22 subjects (39%) using OGTT. The cumulative survival rates of patients with liver cirrhosis and NGT were 94.7% at 5 yr; liver cirrhosis and IGT, 68.8% at 5 yr; liver cirrhosis and DM, 56.6% at 5 yr. The survival rates of patients with liver cirrhosis and DM significantly differed from those with NGT. Univariate analysis demonstrated that serum albumin, total bilirubin, prothrombin activity, Child-Pugh scores, and glucose intolerance were highly significant prognostic factors. Multiple regression analysis yielded albumin and DM as the most powerful independent negative predictors of survival.

CONCLUSIONS

OGTT appears to be useful for evaluating the prognosis of cirrhotic patients.

Elevated circulating adiponectin levels in liver cirrhosis are associated with reduced liver function and altered hepatic hemodynamics

Adiponectin is a novel adipocytokine negatively correlated with parameters of the metabolic syndrome, such as body mass index (BMI), body fat mass (BFM), and circulating insulin levels. Furthermore, metabolic actions directly on the liver have been described. The aim of the present study was to characterize circulating adiponectin levels, hepatic turnover, and the association of adiponectin with key parameters of hepatic as well as systemic metabolism in cirrhosis, a catabolic disease. Circulating adiponectin levels and hepatic turnover were investigated in 20 patients with advanced cirrhosis. Hepatic hemodynamics [portal pressure, liver blood flow, hepatic vascular resistance, indocyanine green (ICG) half-life], body composition, resting energy expenditure, hepatic free fatty acids (FFA) and glucose turnover, and circulating levels of hormones (catecholamines, insulin, glucagon) and proinflammatory cytokines (IL-1beta, TNF-alpha, IL-6) were also assessed. Circulating adiponectin increased dependently on the clinical stage in cirrhosis compared with controls (15.2 +/- 1.7 vs. 8.2 +/- 1.1 microg/ml, respectively, P < 0.01), whereas hepatic extraction decreased. Adiponectin was negatively correlated with parameters of hepatic protein synthesis (prothrombin time: r = -0.62, P = 0.003; albumin: r = -0.72, P < 0.001) but not with transaminases or parameters of lipid metabolism. In addition, circulating adiponectin increased with portal pressure (r = 0.67, P = 0.003), hepatic vascular resistance (r = 0.60, P = 0.008), and effective hepatic blood flow (ICG half-life: r = 0.69, P = 0.001). Adiponectin in cirrhosis was not correlated with BMI, BFM, parameters of energy metabolism, insulin levels, hepatic FFA and glucose turnover, and circulating proinflammatory cytokines. These results demonstrate that 1) adiponectin plasma levels in cirrhosis are significantly elevated, 2) the liver is a major source of adiponectin extraction, and 3) adiponectin levels in cirrhosis do not correlate with parameters of body composition or metabolism but exclusively with reduced liver function and altered hepatic hemodynamics.

Diabetes increases the risk of chronic liver disease and hepatocellular carcinoma

BACKGROUND & AIMS

An association between diabetes and chronic liver disease has been reported. However, the temporal relationship between these conditions remains unknown.

METHODS

We identified all patients with a hospital discharge diagnosis of diabetes between 1985 and 1990 using the computerized records of the Department of Veterans Affairs. We randomly assigned 3 patients without diabetes for every patient with diabetes. We excluded patients with concomitant liver disease. The remaining cohort was followed through 2000 for the occurrence of chronic nonalcoholic liver disease (CNLD) and hepatocellular carcinoma (HCC). Hazard rate ratios (HRR) were determined in Cox proportional hazard survival analysis.

RESULTS

The study cohort comprised 173,643 patients with diabetes and 650,620 patients without diabetes. Most were men (98%). Patients with diabetes were older (62 vs. 54 years) than patients without diabetes. The incidence of chronic nonalcoholic liver disease was significantly higher among patients with diabetes (incidence rate: 18.13 vs. 9.55 per 10,000 person-years, respectively, P < 0.0001). Similar results were obtained for HCC (incidence rate: 2.39 vs. 0.87 per 10,000 person-years, respectively, P < 0.0001). Diabetes was associated with an HRR of 1.98 (95% CI: 1.88 to 2.09, P < 0.0001) of CNLD and an HRR of 2.16 (1.86 to 2.52, P < 0.0001) of hepatocellular carcinoma. Diabetes carried the highest risk among patients with longer than 10 years of follow-up.

CONCLUSIONS

Among men with diabetes, the risk of CNLD and HCC is doubled. This increase in risk is independent of alcoholic liver disease, viral hepatitis, or demographic features.

Hepatic gene expression profiling of streptozotocin-induced diabetes

Diabetes induces biochemical, morphological, and functional alterations in the liver. The liver is a major target of insulin action, and plays a critical role in maintaining blood glucose homeostasis. We investigated the effects of streptozotocin-induced diabetes (SID) on global hepatic gene expression in mice. We induced SID in mice by intraperitoneal injection of streptozotocin. Affymetrix (Santa Clara, CA) microarrays containing probe sets for approximately 11,000 murine genes and expressed sequence tags were used to assess the effects of SID on hepatic gene expression in mice. SID significantly altered the expression of 87 known genes in the liver. SID increased the expression of genes associated with cytoprotective stress responses, oxidative and reductive xenobiotic metabolism, cell cycle inhibition, growth arrest, apoptosis induction, and protein degradation. SID decreased the expression of genes associated with cell proliferation, growth factor signaling, protein synthesis, and xenobiotic metabolism. The novel results reported here should open new areas of investigation in diabetes research and facilitate the development of novel strategies for gene therapy and drug discovery.

Nadolol is superior to isosorbide mononitrate for the prevention of the first variceal bleeding in cirrhotic patients with ascites

BACKGROUND/AIMS

beta-blockers effectively prevent first variceal bleeding (FVB) in cirrhotic patients. In patients with ascites, however, their use might be precluded by a high rate of contraindications and side effects. We compared the efficacy and applicability of nadolol and isosorbide-mononitrate (IsMn) in preventing FVB in a population of cirrhotic patients at high risk of variceal bleeding with ascites, who can be frequently intolerant to beta-blockers.

METHODS

A total of 80 consecutive cirrhotic patients with ascites and esophageal varices (25% average risk of bleeding at 1 year) were considered, 28 were excluded due to contraindications and 52 were randomly assigned to receive nadolol (n=25) or IsMn (n=27).

RESULTS

Frequency of contraindications was greater for beta-blockers than IsMn (35 versus 0%, P=0.001). During 21.3+/-11.6 months of follow-up, side effects forced six patients taking nadolol and four taking IsMn to stop treatment. Bleeding occurred in two patients taking nadolol and ten taking IsMn. The probability of bleeding was significantly lower in the nadolol group (P<0.05), whereas overall survival was similar (seven patients on IsMn and eight on nadolol died, P=0.3).

CONCLUSIONS

In patients with ascites IsMn is tolerated but ineffective while nadolol is effective but less tolerated.

Vegetarian diets in hepatic encephalopathy: facts or fantasies?

Diet treatment characterized by a reduction in or a selection of food proteins is currently suggested in hepatic encephalopathy. This article is a review of the present knowledge about the characteristics and the rationale of vegetarian diets in cirrhotic patients with overt or latent encephalopathy. In addition, evidence relating diet and encephalopathy and the nutritional features and needs of cirrhotic patients is reported. Finally, the rationale of a diet based on vegetable and milk-derived proteins that may overcome the limits and the possible adverse effects of a strict vegetarian diet is presented.

Hepatic nonoxidative disposal of an oral glucose meal in patients with liver cirrhosis

Seven patients with liver cirrhosis and five healthy subjects were studied over 4 hours after ingestion of a glucose meal to determine whether alterations of hepatic nonoxidative glucose disposal participate in the pathogenesis of impaired glucose tolerance. Hepatic uridyl-diphosphoglucose (UDPG) turnover was calculated from the isotopic enrichment of urinary acetaminophen glucuronide during continuous infusion of 13C-galactose and used as an index of hepatic glycogen synthesis. Patients with cirrhosis had postprandial hyperglycemia and decreased glucose clearance, but hepatic UDPG turnover was not altered (1.84 +/- 0.29 mg/kg fat-free mass min v 1.76 +/- 0.15 in controls, nonsignificant). It is concluded that hepatic postprandial glycogen synthesis is unaltered in patients with advanced cirrhosis, demonstrating important hepatic functional reserve.

Diabetes and the hepatobiliary system

Diabetes mellitus can lead to metabolic changes that alter normal hepatic and biliary function and structure. These alterations in hepatic and biliary function and structure are usually benign, but in certain situations lead to significant, disabling disease. This article reviews the hepatic and biliary complications of diabetes, with emphasis on epidemiology, diagnosis, and management, as well as the glucose intolerance seen in liver disease.

Hyperinsulinemia accompanying hyperglycemia in Chinese patients with aplastic anemia

Serum insulin, and plasma glucagon and glucose levels were measured in 56 Chinese patients with aplastic anemia (AA) and 40 normal controls. Serum insulin and plasma glucose levels in 18 newly diagnosed cases and 11 previously treated cases with prednisone were significantly higher than those in the controls. Serum insulin and plasma glucose levels in 27 cases previously treated with stanozolol were significantly higher than those in the newly diagnosed cases and the previously treated cases with prednisone. There was no significant difference in plasma glucagon levels between the patients and the controls. Serum insulin and plasma glucose levels were significantly correlated with the amount of blood transfusions and serum ferritin and cortisone concentrations in the AA patients. Our findings suggest that AA patients may have hyperinsulinemia accompanying hyperglycemia, which can be further aggravated by stanozolol and prednisone therapy and iron overload.

Glucose intolerance in liver cirrhosis: role of hepatic and non-hepatic influences

Oral glucose tolerance was tested in a heterogeneous group of 108 patients with liver cirrhosis. Data were compared with those from 181 subjects without liver disease (44% normal, 35% impaired glucose tolerance and 21% type 2 diabetes mellitus). In cirrhosis, 27% of the patients had normal, 36% had impaired glucose tolerance, and 37% were diabetic. There was no association between glucose intolerance or diabetes and the aetiology of cirrhosis, the duration of the disease, the biochemical indicators of hepatocyte damage, cholestasis and/or liver function. Only weak associations were found between the results of quantitative liver functions tests (caffeine, xylocaine, indocyanine green) and basal and post load glucose and insulin concentrations. Cirrhotics with 1st degree relatives with type 2 diabetes mellitus (n = 16) did not show an increased prevalence of diabetes. Older and/or malnourished patients were more frequently glucose intolerant. Using the plasma glucose concentration 120 minutes after glucose load as the dependent variable, multivariate regression analysis showed that 54% of its variance is associated with the following variables: basal plasma glucose (36%) and free fatty acid concentration (5%), age (3%), basal glucose oxidation rate (3%), muscle mass (3%) and plasma free glycerol at 120 minutes after glucose load (3%). By contrast, the clinical state of the patients (i.e. the CHILD-Pugh score) accounted for only 2% of the variance. We conclude that glucose tolerance is variable in cirrhosis. After manifestation of liver disease, glucose intolerance or diabetes cannot be explained by the clinical, histological or biochemical signs of liver disease.