Gianfranco Pagano

Meta-analysis: natural history of non-alcoholic fatty liver disease (NAFLD) and diagnostic accuracy of non-invasive tests for liver disease severity.

Abstract Background. NAFLD ranges from simple steatosis (SS) to non-alcoholic steatohepatitis (NASH). The natural history of NAFLD and the optimal strategy to identify subjects with progressive liver disease are unclear. Objectives. To assess the evidence in: (1) natural history of NAFLD; and (2) non-invasive methods to differentiate NAFLD histological subtypes. Design and setting. Among 4185 articles published on MEDLINE, Cochrane Library, EMBASE, Pubmed, national and International meeting abstracts through July 2010, 40 articles assessing the natural history of NAFLD and 32 articles evaluating the diagnostic accuracy of non-invasive tests against liver biopsy (LB) were included. Measurements. Two reviewers retrieved articles and evaluated study quality by appropriate scores. Main outcomes were pooled using random- or fixed-effects models. Results. NAFLD has an increased overall mortality (OR: 1.57, 95% CI: 1.18–2.10), deriving from liver-related and cardiovascular disease, and a 2-fold risk of diabetes. Compared to SS, NASH has a higher liver-related (OR for NASH: 5.71, 2.31–14.13; OR for NASH with advanced fibrosis: 10.06, 4.35–23.25), but not cardiovascular mortality (OR: 0.91, 0.42–1.98). Three non-invasive methods received independent validation: pooled AUROC, sensitivity and specificity of cytokeratin-18 for NASH are 0.82 (0.78–0.88), 0.78 (0.64–0.92), 0.87 (0.77–0.98). For NASH with advanced fibrosis, pooled AUROC, sensitivity and specificity of NAFLD fibrosis score and Fibroscan are 0.85 (0.80–0.93), 0.90 (0.82–0.99), 0.97 (0.94–0.99) and 0.94 (0.90–0.99), 0.94 (0.88–0.99) and 0.95 (0.89–0.99). Conclusions. NAFLD warrants screening for cardio-metabolic risk and for progressive liver disease. The combination of three noninvasive tests with LB may optimally individuate patients with NASH, with or without advanced fibrosis.

An in vivo and in vitro study of the mechanism of prednisone-induced insulin resistance in healthy subjects.

Prednisone-induced insulin resistance may depend on either reduced sensitivity (receptor defect) or reduced response to insulin (postreceptor defect). To clarify the mechanism of prednisone-induced insulin resistance, a [3H]glucose infusion (1 microCi/min) was performed for 120 min before and during a euglycemic clamp repeated at approximately 100, approximately 1,000, and approximately 10,000 microU/ml steady state plasma insulin concentration in 10 healthy, normal weight subjects, aged 35 +/- 7 yr. Each test was repeated after 7-d administration of placebo or prednisone (15 plus 15 mg/d per subject), in a randomized sequence with an interval of 1 mo between the two tests. Mean fasting blood glucose (89.5 +/- 2.1 vs. 83.7 +/- 1.9 mg/dl) and mean fasting plasma insulin values (17.8 +/- 1.2 vs. 14.3 +/- 0.8 microU/ml) were significantly higher (P less than 0.01) after prednisone. The insulin sensitivity index (glucose metabolic clearance rate in ml/kg per min) was significantly lower (P less than 0.001) after prednisone at all three steady state plasma insulin levels: 2.8 +/- 0.3 vs. 7.4 +/- 1.1 at approximately 100 microU/ml; 6.0 +/- 0.5 vs. 12.2 +/- 1.1 at approximately 1,000 microU/ml; 7.4 +/- 0.6 vs. 14.4 +/- 0.5 at approximately 10,000 microU/ml. Fasting glucose production (in mg/kg per min) was significantly higher after prednisone: 3.7 +/- 0.2 vs. 2.9 +/- 0.2, P less than 0.001. Suppression of glucose production at steady state plasma insulin level of approximately 100 microU/ml was less after prednisone (1.01 +/- 0.35 vs. 0.14 +/- 0.13, NS), and total at approximately 1,000 and approximately 10,000 microU/ml after both prednisone and placebo. The metabolic kinetic parameters of insulin after prednisone were not significantly different from those after placebo. In addition, insulin binding and 3-ortho-methyl-glucose transport were studied in vitro on fat cells from 16 normal-weight surgical candidates aged 40 +/- 8 yr (10 treated with placebo and 6 with prednisone as above). No significant difference was observed with regard to specific insulin binding (tested with 1 ng/ml hormone only), whereas significant transport differences were noted at the basal level (0.40 +/- 0.10 vs. 0.54 +/- 0.12 pmol/10(5) cells, P less than 0.05), and at increasing concentrations up to the maximum stimulation values (5 ng/ml): 0.59 +/- 0.04 vs. 0.92 +/- 0.12 pmol/10(5) cells, P less than 0.005. These results suggest that (a) administration of an anti-inflammatory dose of prednisone for 7 d induces insulin resistance in man; (b) this is more dependent on depressed peripheral glucose utilization than on increased endogenous production; (c) total insulin binding on isolated adipocytes is not significantly affected; (d) insulin resistance is primarily the outcome of postreceptor defect (impaired glucose transport).

Adipokines in NASH: Postprandial lipid metabolism as a link between adiponectin and liver disease†

Circulating levels of four adipokines (adiponectin, TNF‐α, leptin, and resistin) and the postprandial lipid and adiponectin responses to an oral fat load were assessed in 25 non‐obese, non‐diabetic patients with biopsy‐proven nonalcoholic steatohepatitis (NASH) and correlated with metabolic indices and liver histology. Circulating adiponectin was lower in NASH compared with controls (5,476 ± 344 vs. 11,548 ± 836 ng/mL; P = .00001) and on multiple regression analysis correlated negatively with liver steatosis, necroinflammation (OR = 5.0; P = .009), and fibrosis (OR = 8.0; P = .003).The magnitude of postprandial lipemia was significantly higher in NASH than in controls and was related to fasting adiponectin (β = −0.78; P = .00003). Controls showed a significant increase in serum adiponectin in response to the fat load, whereas patients with NASH showed a slight decrease. Postprandial free fatty acids response correlated inversely with adiponectin response in both groups and independently predicted the severity of liver steatosis in NASH (β = 0.51; P = .031). In conclusion, hypoadiponectinemia is present before overt diabetes and obesity appear and correlates with the severity of liver histology in NASH. Impaired postprandial lipid metabolism may be an additional mechanism linking hypoadiponectinemia and NASH and posing a higher cardiovascular risk to these subjects. The mechanism(s) underlying these differences are unknown, but the type of dietary fat seems to play a role. These findings may have important pathogenetic and therapeutic implications in both liver and metabolic disease. (HEPATOLOGY 2005.)

Hypoadiponectinemia Predicts the Severity of Hepatic Fibrosis and Pancreatic Beta-Cell Dysfunction in Nondiabetic Nonobese Patients with Nonalcoholic Steatohepatitis

OBJECTIVES:The relationships between the adipokines tumor necrosis factor (TNF)-α and adiponectin and the parameters of glucose homeostasis and severity of liver disease were assessed in nonobese nondiabetic subjects with nonalcoholic steatohepatitis (NASH).METHODS:A frequently sampled intravenous glucose tolerance test, serum cytokine measurement, and 7-day alimentary record were performed in 20 biopsy-proven NASH patients and 45 age-, sex-, and BMI-matched controls (30 insulin sensitive and 15 insulin resistant).RESULTS:Patients with NASH had impaired pancreatic β-cell function compared with both insulin-sensitive (adaptation index, AI: 97.7 ± 17.7 vs 307.4 ± 24.1 min−2 mmol−1 L; p = 0.00001) and insulin-resistant (adaptation index, AI: 97.7 ± 17.7 vs 201.4 ± 41.1 min−2 mmol−1 L; p = 0.001) controls. Serum adiponectin levels were also significantly lower in the NASH group than in the two control groups and correlated with adaptation index and with the severity of hepatic steatosis, necroinflammation, and fibrosis. When NASH patients were grouped according to the severity of histological liver damage, adiponectin was the only variable discriminating patients with higher necroinflammatory grade and fibrosis score from those with milder lesions.CONCLUSIONS:β-cell secretory impairment is present in nonobese patients with NASH before glucose intolerance appears and may contribute to their increased risk for developing diabetes. Hypoadiponectinemia is a feature of NASH and may have a pathogenetic role in β-cell dysfunction and in hepatic necroinflammation and fibrosis, independently of insulin resistance, visceral fat accumulation, TNF-α axis activity, and dietary habits. Our findings provide further rationale for therapeutic approaches aimed at increasing adiponectin levels together with restoring β-cell function and insulin sensitivity.

A novel approach to control hyperglycemia in type 2 diabetes: Sodium glucose co-transport (SGLT) inhibitors. Systematic review and meta-analysis of randomized trials

Abstract Background. Current treatment of hyperglycemia in type 2 diabetes (T2DM) is often ineffective and has unwanted effects. Therefore, novel antidiabetic drugs are under development. Objective. To assess efficacy and safety of the new antidiabetic drugs sodium glucose co-transport-2 (SGLT2) inhibitors in T2DM. Design and setting. Among 151 articles published on MEDLINE, Cochrane Library, EMBASE, PubMed, International meeting abstracts through December 2010, 13 randomized placebo-controlled trials (RCT) were included. Measurements. Two reviewers retrieved articles and evaluated study quality by appropriate scores. Main outcomes were pooled using random- or fixed-effects models. Results. Dapagliflozin significantly reduced HbA1c (weighted mean difference (WMD) −0.52%; 95% CI −0.46, −0.57%; P < 0.00001) fasting plasma glucose (WMD −18.28 mg/dL; 95% CI −20.66, −15.89; P < 0.00001), body mass index (WMD −1.17%; −1.41, −0.92%; P < 0.00001), systolic (WMD −4.08 mmHg; −4.91, −3.24), and diastolic (WMD −1.16 mmHg; −1.67, −0.66) blood pressure, and serum uric acid (WMD −41.50 μmol/L; −47.22, −35.79). Other SGLT2 inhibitors showed similar results. Dapagliflozin treatment increased the risk of urinary (OR 1.34; 1.05–1.71) and genital (OR 3.57; 2.59–4.93) tract infection; it also mildly increased the risk of hypoglycemia (OR 1.27; 1.05–1.53) when co-administered with insulin. Limitations. Limitations of the literature include the small number, size, and duration of RCTs. Conclusions. Pending confirmation from larger RCTs, this analysis shows SGLT2 inhibitors are safe and effective for hyperglycemia treatment in T2DM.

Should Nonalcoholic Fatty Liver Disease Be Included in the Definition of Metabolic Syndrome? A cross-sectional comparison with Adult Treatment Panel III criteria in nonobese nondiabetic subjects

OBJECTIVE—The ability of the Adult Treatment Panel III (ATP III) criteria of metabolic syndrome to identify insulin-resistant subjects at increased cardiovascular risk is suboptimal, especially in the absence of obesity and diabetes. Nonalcoholic fatty liver disease (NAFLD) is associated with insulin resistance and is emerging as an independent cardiovascular risk factor. We compared the strength of the associations of ATP III criteria and of NAFLD to insulin resistance, oxidative stress, and endothelial dysfunction in nonobese nondiabetic subjects. RESEARCH DESIGN AND METHODS—Homeostasis model assessment of insulin resistance (HOMA-IR) >2, oxidative stress (nitrotyrosine), soluble adhesion molecules (intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin), and circulating adipokines (tumor necrosis factor-α, leptin, adiponectin, and resistin) were cross-sectionally correlated to ATP III criteria and to NAFLD in 197 unselected nonobese nondiabetic subjects. RESULTS—NAFLD more accurately predicted insulin resistance than ATP III criteria: sensitivity 73 vs. 38% (P = 0.0001); positive predictive value: 81 vs. 62% (P = 0.035); negative predictive value 87 vs. 74% (P = 0.012); positive likelihood ratio 4.39 vs. 1.64 (P = 0.0001); and negative likelihood ratio 0.14 vs. 0.35 (P = 0.0001). Adding NAFLD to ATP III criteria significantly improved their diagnostic accuracy for insulin resistance. Furthermore, NAFLD independently predicted HOMA-IR, nitrotyrosine, and soluble adhesion molecules on logistic regression analysis; the presence of NAFLD entailed more severe oxidative stress and endothelial dysfunction, independent of adiposity or any feature of the metabolic syndrome in insulin-resistant subjects. CONCLUSIONS—NAFLD is more tightly associated with insulin resistance and with markers of oxidative stress and endothelial dysfunction than with ATP III criteria in nonobese nondiabetic subjects and may help identify individuals with increased cardiometabolic risk in this population.

Dietary fat and gestational hyperglycaemia

Abstract.Aims/hypothesis: The purpose of this study was to investigate the relation between life-style habits and glucose abnormalities in Caucasian women with and without conventional risk factors for gestational diabetes. Methods: A total of 126 pregnant women with gestational diabetes, 84 with impaired glucose tolerance and 294 with normal glucose tolerance, identified by sequential screening, were interviewed to determine their usual weekly food pattern, amount of exercise, smoking habits and alcohol intake. Results: Patients with glucose abnormalities were older and shorter in height and had significantly higher BMI before pregnancy, percentage of diabetic first-degree relatives and higher intake of saturated fat. Patients without known risk factors for gestational diabetes (i. e. younger than 35 years of age, BMI < 25 kg/m2, no first-degree diabetic relatives) included 40 with impaired glucose tolerance or gestational diabetes. In a multiple logistic regression model age, short stature, familial diabetes, BMI and percentages of saturated fat were associated with impaired glucose tolerance or gestational diabetes in all patients, after adjustment for gestational age. In patients without conventional risk factors only percentages of saturated fat (OR = 2.0; 95 %-CI = 1.2–3.2) and polyunsaturated fat (OR = 0.85; 95 %-CI = 0.77–0.92) were associated with gestational hyperglycaemia, after adjustment for age, gestational age and BMI. Conclusion/interpretation: Saturated fat has an independent role in the development of gestational glucose abnormalities. This role is more important in the absence of conventional risk factors suggesting that glucose abnormalities could be prevented during pregnancy, at least in some groups of women. [Diabetologia (2001) 44: 972–978]

Mechanism of insulin resistance in human liver cirrhosis. Evidence of a combined receptor and postreceptor defect.

Insulin resistance in liver cirrhosis may depend on either reduced sensitivity (receptor defect) and/or reduced response to insulin (postreceptor defect). To clarify the mechanism of such resistance, a [3H]glucose infusion (0.2 microCi/min) was performed for 120 min before and during a euglycemic clamp at approximately 100, 1,000, and 10,000 microU/ml steady state plasma insulin concentration in 18 compensated cirrhotics with portal hypertension and impaired glucose tolerance, and 18 healthy volunteers with no family history of diabetes, matched for sex, age, and weight. Mean fasting plasma insulin (29.2 +/- 3.4 SEM vs. 14.8 +/- 1.1 microU/ml) was significantly higher (P less than 0.001) in cirrhotics, while fasting plasma glucose was much the same in the two groups. Glucose use (milligrams per kilogram per minute) was significantly lower in cirrhotics at all three steady state plasma insulin levels: 3.04 +/- 0.34 vs. 7.72 +/- 0.61 (P less than 0.001) at approximately 100; 6.05 +/- 1.07 vs. 11.45 +/- 1.24 (P less than 0.001) at approximately 1,000; and 11.69 +/- 0.69 vs. 14.13 +/- 0.74 (P less than 0.05) at approximately 10,000 microU/ml. Mean plasma C-peptide was significantly higher in cirrhotics both basally and during the steady states (P less than 0.001); it was completely suppressed at approximately 10,000 microU/ml in controls and only 57.5% of the baseline in cirrhotics. Endogenous glucose production (milligrams per kilogram per minute) was much the same in the two groups in the fasting state and almost entirely suppressed in the controls (0.10 +/- 0.05 vs. 0.48 +/- 0.11, P less than 0.001) at approximately 100 microU/ml; at approximately 1,000 microU/ml a residual glucose production, 0.07 +/- 0.05, was observed in the cirrhotics only. In addition, insulin binding and 3-ortho-methyl-glucose transport were studied in vitro in six cirrhotics and six controls. Insulin binding to circulating monocytes and isolated adipocytes was significantly lower (P less than 0.025) in cirrhotics in all insulin concentration studies. Glucose transport values on isolated adipocytes were significantly lower in cirrhotics both basally (P less than 0.001) and at maximal insulin concentration (P less than 0.05). These results suggest that insulin resistance in human cirrhosis is more dependent on depressed peripheral glucose use than on increased endogenous glucose production, and that a combined receptor and postreceptor defect in insulin action on target cells seems to be present.

p53 Mediates the Accelerated Onset of Senescence of Endothelial Progenitor Cells in Diabetes

Adverse metabolic factors, including oxidized small and dense low density lipoprotein (ox-dmLDL) can contribute to the reduced number and the impaired functions of circulating endothelial progenitors (EPC) in diabetic patients. To elucidate the molecular mechanisms involved, EPC from normal donors were cultured in the presence of ox-dmLDL. Under these experimental conditions EPC undergo to senescent-like growth arrest. This effect is associated with Akt activation, p21 expression, p53 accumulation, and retinoblastoma protein dephosphorylation and with a reduced protective effect against oxidative damage. Moreover, depletion of endogenous p53 expression by small interfering RNA demonstrates that the integrity of this pathway is essential for senescence to occur. Activation of the Akt/p53/p21 signaling pathway and accelerated onset of senescence are also detectable in EPC from diabetic patients. Finally, diabetic EPC depleted of endogenous p53 do not undergo to senescence-growth arrest and acquire the ability to form tube-like structures in vitro. These observations identify the activation of the p53 signaling pathway as a crucial event that can contribute to the impaired neovascularization in diabetes.

Hypouricemia and hyperuricemia in type 2 diabetes: two different phenotypes.

Background and Design Conflicting data exist about uric acid levels in type 2 diabetes mellitus, as low levels were found in diabetic patients, while elevated serum uric acid is a feature of hyperinsulinemia and impaired glucose tolerance. The present study was addressed to evaluate the relation between uric acid and metabolic parameters, creatinine clearance and albumin excretion rate in a cohort of type 2 diabetic patients.