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Objective:Non-alcoholic fatty liver disease (NAFLD) is associated with abnormalities in basal glucose and free fatty acid (FFA) metabolism, multi-organ insulin resistance and alterations in lipoprotein kinetics. These metabolic outcomes can be evaluated in vivo by using stable isotopically labeled tracer methods. An understanding of the reproducibility of these measures is necessary to ensure adequate statistical power in studies designed to evaluate metabolic function in subjects with NAFLD.Methods:We determined the degree of intra-individual variability of skeletal muscle, adipose tissue, and hepatic insulin sensitivity and basal plasma glucose, FFA, and very-low-density lipoprotein triglyceride and apolipoprotein B-100 (apoB-100) kinetics in eight obese subjects with NAFLD (age: 44±3 years; body mass index: 38.2±1.7 kg m−2; intrahepatic triglyceride content: 24.5±3.9%), by using the hyperinsulinemic-euglycemic clamp technique and stable isotope-labeled tracer methods and mathematical modeling on two separate occasions ∼2 months apart.Results:The intra-individual variability (coefficient of variation) ranged from 6% for basal glucose production to 21% for insulin-stimulated glucose disposal (percentage increase from basal). We estimated that a 25% difference in any outcome measure can be detected with a sample size of 8 subjects for paired studies and 15 subjects per group for unpaired studies, assuming an α value of 0.05 and a β value of 0.20 (that is, 80% power).Conclusion:These results demonstrate that only a small number of subjects are needed to detect clinically relevant effects in insulin sensitivity and hepatic lipoprotein metabolism in obese subjects with NAFLD, and will be useful to determine appropriate sample size for future metabolic studies. [ABSTRACT FROM AUTHOR]

BACKGROUND:: Obese patients are often affected by hypertension, dyslipidaemia, impaired glucose metabolism, and suffer from cardiovascular disease (CVD), related to the characteristic metabolic alterations. AIM OF THE STUDY:: To evaluate reduction of risk factors for CVDs in morbid-obese patients (body mass index (BMI)>40kg/m2) after weight loss upon bariatric surgery intervention of biliary-intestinal bypass. SUBJECTS:: 45 (17 men, 28 women) morbid-obese patients (age: 19-49?y, BMI>40?kg/m2). All patients were selected on the basis of medical history, physical and biochemical evaluation and of psychiatric tests, which were performed on all individuals admitted to our Day Hospital to verify the safety of surgical intervention. MEASUREMENTS:: Body weight, body composition (by dual X-ray absorptiometry, DXA), blood pressure, lipid profile, fibrinogen and glucose metabolism were monitored at baseline and 1, 3, 6, 9, 12, 24 and 36 months after surgery. RESULTS:: A significant and persistent weight loss was present in all patients at the end of the 3?y follow-up period (P<0.001), with a progressive reduction of total and trunk fat mass as evaluated by means of DXA. Additionally, a parallel significant reduction in systolic (P<0.001) and diastolic (P<0.001) blood pressure was observed. Total and LDL cholesterol were significantly reduced (P<0.001), while HDL showed no modifications; triglycerides declined progressively during the 3?y follow-up (P<0.001). Fibrinogen decreased from 364.5±82.4 to 266.4±45.7?mg/dl at the end of the period (P<0.001). Fasting glucose levels and glucose levels 120?min after an oral glucose tolerance test were reduced from 95.1±20.3 to 78.6±9.1?mg/dl (P<0.001) and from 116.9±34.7 to 77.6±15.5?mg/dl (P<0.001), respectively, at baseline and at the end of the study. Moreover, fasting insulin decreased from 30.0±20.4 to 8.6±2.9?µUI/ml (P<0.001) after 3?y, while insulin levels after (120?min) oral glucose load decreased from 105.5±61.5 to 12.0±6.0?µUI/ml (P<0.001). CONCLUSION:: Our results show that biliary-intestinal bypass may represent a valid and alternative therapeutic approach in patients with morbid obesity since it induces a significant and stable reduction of body weight and obesity-related risk factors for CVD.International Journal of Obesity (2004) 28, 1600-1606. doi:10.1038/sj.ijo.0802782 [ABSTRACT FROM AUTHOR]