title: Reference ranges of HOMA-IR in normal-weight and obese young Caucasians.
abstract: OBJECTIVE
  Insulin resistance (IR) may develop very early in life being associated with occurrence of cardiometabolic risk factors (CMRFs). Aim of the present study was to identify in young Caucasians normative values of IR as estimated by the homeostasis model assessment (HOMA-IR) and cutoffs diagnostic of CMRFs.
  
  
  METHODS
  Anthropometrics and biochemical parameters were assessed in 2753 Caucasians (age 2-17.8 years; 1204 F). Reference ranges of HOMA-IR were defined for the whole population and for samples of normal-weight and overweight/obese individuals. The receiver operator characteristic analysis was used to find cutoffs of HOMA-IR accurately identifying individuals with any CMRF among total cholesterol and/or triglycerides higher than the 95th percentile and/or HDL cholesterol lower than the 5th for age and sex, impaired glucose tolerance, and alanine aminotransferase levels ≥40 U/l.
  
  
  RESULTS
  Overweight/obese individuals had higher HOMA-IR levels compared with normal-weight peers (p < 0.0001) at any age. HOMA-IR index rose progressively with age, plateaued between age 13 and 15 years and started decreasing afterward. HOMA-IR peaked at age 13 years in girls and at 15 years in boys. The 75th percentile of HOMA-IR in the whole population (3.02; AUROC = 0.73, 95 % CI = 0.70-0.75), in normal-weight (1.68; AUROC = 0.76, 95 % CI = 0.74-0.79), and obese (3.42; AUROC = 0.71, 95 % CI = 0.69-0.72) individuals identified the cutoffs best classifying individuals with any CMRF.
  
  
  CONCLUSIONS
  Percentiles of HOMA-IR varied significantly in young Caucasians depending on sex, age, and BMI category. The 75th percentile may represent an accurate cutoff point to suspect the occurrence of one or more CMRFs among high total cholesterol and triglycerides, low HDL cholesterol, and ALT ≥ 40 UI/l.
authors.affiliation: Research Unit for Multifactorial Diseases, Scientific Directorate, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Blegina
authors.initials: B
authors.lastname: Shashaj
authors.affiliation: Department of Laboratory Medicine, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Luciano
authors.affiliation: Research Unit for Multifactorial Diseases, Scientific Directorate, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Benedetta
authors.initials: B
authors.lastname: Contoli
authors.affiliation: Unit for Clinical Nutrition, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Giuseppe Stefano
authors.initials: GS
authors.lastname: Morino
authors.affiliation: Unit for Clinical Nutrition, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Spreghini
authors.affiliation: Unit for Clinical Nutrition, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Rustico
authors.affiliation: Unit for Clinical Nutrition, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Rita Wietrzycowska
authors.initials: RW
authors.lastname: Sforza
authors.affiliation: Research Unit for Multifactorial Diseases, Scientific Directorate, Bambino Gesù Children Hospital, Rome, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Dallapiccola
authors.affiliation: Research Unit for Multifactorial Diseases, Scientific Directorate, Bambino Gesù Children Hospital, Rome, Italy. melaniamanco@tiscali.it.
authors.forename: Melania
authors.initials: M
authors.lastname: Manco
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000886:Anthropometry; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D005260:Female; D006706:Homeostasis; D006801:Humans; D007333:Insulin Resistance; D007558:Italy / Q000453:epidemiology; D008297:Male; D008954:Models, Biological; D009765:Obesity / Q000378:metabolism*; D050177:Overweight / Q000378:metabolism; D012372:ROC Curve; D012016:Reference Values; D012307:Risk Factors; D012737:Sex Factors; D044465:White People
keywords: Children; HOMA-IR; Insulin resistance; Metabolic syndrome; Obesity