title: Surrogate measures of insulin sensitivity when compared to euglycemic hyperinsulinemic clamp studies in Asian Indian men without diabetes.
abstract: OBJECTIVE
  Fasting surrogate measures of insulin sensitivity are increasingly used in research and clinical practice. To assess the reliability of these measures, we aimed to evaluate multiple fasting surrogate measures simultaneously in non-diabetic subjects in comparison with the euglycemic hyperinsulinemic clamp study.
  
  
  METHODS
  Sixteen normoglycemic male South Indian subjects were studied. After an overnight fast, blood samples were collected for glucose, insulin and lipid profile measurements, and stepped euglycemic hyperinsulinemic clamp studies were performed on all subjects. Steady state glucose infusion rates (M value) during low and high insulin phases of the clamp were calculated. Correlation of M value with surrogate markers of insulin sensitivity was performed. Predictive accuracy of surrogate indices was measured in terms of Root Mean Squared Error (RMSE) and leave-one-out cross-validation-type RMSE of prediction using a calibration model.
  
  
  RESULTS
  M values showed a strong and significant correlation (p<0.01) with the following surrogate markers: Fasting insulin (r=-0.714), Fasting glucose to insulin ratio (FGIR, r=0.747) and Raynaud index (r=0.714). FGIR had a significantly lower RMSE when compared with HOMA-IR and QUICKI.
  
  
  CONCLUSIONS
  Among the surrogate measures, FGIR had the strongest correlation with M values. FGIR was also the most accurate surrogate measure, as assessed by the calibration model.
authors.affiliation: Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, India.
authors.forename: Padmanaban
authors.initials: P
authors.lastname: Venkatesan
authors.affiliation: Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Akankasha
authors.initials: A
authors.lastname: Tiwari
authors.affiliation: Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, India.
authors.forename: Riddhi
authors.initials: R
authors.lastname: Dasgupta
authors.affiliation: Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Carey
authors.affiliation: Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Kehlenbrink
authors.affiliation: Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Anneka
authors.initials: A
authors.lastname: Wickramanayake
authors.affiliation: Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, India.
authors.forename: Mohan
authors.initials: M
authors.lastname: Jambugulam
authors.affiliation: Department of Biostatistics, Christian Medical College, Vellore, India.
authors.forename: Lakshmanan
authors.initials: L
authors.lastname: Jeyaseelan
authors.affiliation: Department of Biostatistics, Christian Medical College, Vellore, India.
authors.forename: Kavitha
authors.initials: K
authors.lastname: Ramanathan
authors.affiliation: Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, USA.
authors.forename: Meredith
authors.initials: M
authors.lastname: Hawkins
authors.affiliation: Department of Endocrinology, Diabetes and Metabolism, Christian Medical College, Vellore, India. Electronic address: nihal_thomas@cmcvellore.ac.in.
authors.forename: Nihal
authors.initials: N
authors.lastname: Thomas
mesh_terms: D000328:Adult; D044466:Asian People; D015415:Biomarkers / Q000032:analysis* / Q000378:metabolism; D005215:Fasting / Q000097:blood; D015309:Glucose Clamp Technique / Q000379:methods; D005951:Glucose Tolerance Test; D006801:Humans; D007194:India; D007328:Insulin / Q000008:administration & dosage* / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007328:Insulin
keywords: Calibration model; Ethnic groups; Glucose clamp technique; Insulin resistance; Insulin sensitivity; Surrogate measures