title: Fasting-based estimates of insulin sensitivity in overweight and obesity: a critical appraisal.
abstract: OBJECTIVE
  To identify simple methods to estimate the degree of insulin resistance.
  
  
  METHODS
  The performance of a wide range of fasting-based index estimates of insulin sensitivity was compared by receiver operating characteristic analysis (area under curves and their 95% confidence intervals) against the M value from euglycemic insulin clamp studies collected in the San Antonio (non-Hispanic whites and Hispanic residents of San Antonio, TX) and European Group for the Study of Insulin Resistance (non-diabetic white Europeans) databases (n = 638).
  
  
  RESULTS
  Insulin resistance differed substantially between lean (BMI < 25 kg/m2), overweight or obese (BMI > or = 25 kg/m2), and type 2 diabetic individuals. Estimates of insulin resistance were, therefore, assessed in each group separately. In the overweight and obese subgroup (n = 302), the receiver operating characteristic performance of fasting-based indices varied from 0.72 (0.62 to 0.82), in the case of the insulin/glucose ratio, to 0.80 (0.72 to 0.88) in the case of Belfiore free fatty acids. One superior method could not be identified; the confidence intervals overlapped, and no statistically significant differences emerged. All indices performed better when using the whole study population, with fasting plasma insulin, homeostatic model assessment, insulin/glucose ratio, quantitative insulin sensitivity check index, glucose/insulin ratio, Belfiore glycemia, revised quantitative insulin sensitivity check index, McAuley index, and Belfiore free fatty acids showing area under curves of 0.83, 0.90, 0.66, 0.90, 0.66, 0.90, 0.85, 0.83, and 0.86, respectively, because of the inclusion of very insulin sensitive (lean) and very insulin resistant cases (diabetic subjects).
  
  
  CONCLUSIONS
  In conclusion, a superior fasting-based index estimate to distinguish between the presence and absence of insulin resistance in overweight and obesity could not be identified despite the use of the large datasets.
authors.affiliation: Department of Diabetology, Metabolism and Clinical Nutrition, Faculty of Medicine, University Hospital Antwerp, Wilrijkstraat 10, B-2650 Edegem, Antwerp, Belgium.
authors.forename: Johannes B
authors.initials: JB
authors.lastname: Ruige
authors.forename: Ilse L
authors.initials: IL
authors.lastname: Mertens
authors.forename: Ellen
authors.initials: E
authors.lastname: Bartholomeeusen
authors.forename: Eveline
authors.initials: E
authors.lastname: Dirinck
authors.forename: Ele
authors.initials: E
authors.lastname: Ferrannini
authors.forename: Luc F
authors.initials: LF
authors.lastname: Van Gaal
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000175:diagnosis; D005215:Fasting / Q000378:metabolism* / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin