title: Fasting insulin sensitivity indices are not better than routine clinical variables at predicting insulin sensitivity among Black Africans: a clamp study in sub-Saharan Africans.
abstract: BACKGROUND
  We aimed to evaluate the predictive utility of common fasting insulin sensitivity indices, and non-laboratory surrogates [BMI, waist circumference (WC) and waist-to-height ratio (WHtR)] in sub-Saharan Africans without diabetes.
  
  
  METHODS
  We measured fasting glucose and insulin, and glucose uptake during 80/mU/m2/min euglycemic clamp in 87 Cameroonians (51 men) aged (SD) 34.6 (11.4) years. We derived insulin sensitivity indices including HOMA-IR, quantitative insulin sensitivity check index (QUICKI), fasting insulin resistance index (FIRI) and glucose-to-insulin ratio (GIR). Indices and clinical predictors were compared to clamp using correlation tests, robust linear regressions and agreement of classification by sex-specific thirds.
  
  
  RESULTS
  The mean insulin sensitivity was M = 10.5 ± 3.2 mg/kg/min. Classification across thirds of insulin sensitivity by clamp matched with non-laboratory surrogates in 30-48% of participants, and with fasting indices in 27-51%, with kappa statistics ranging from -0.10 to 0.26. Fasting indices correlated significantly with clamp (/r/=0.23-0.30), with GIR performing less well than fasting insulin and HOMA-IR (both p < 0.02). BMI, WC and WHtR were equal or superior to fasting indices (/r/=0.38-0.43). Combinations of fasting indices and clinical predictors explained 25-27% of variation in clamp values.
  
  
  CONCLUSIONS
  Fasting insulin sensitivity indices are modest predictors of insulin sensitivity measured by euglycemic clamp, and do not perform better than clinical surrogates in this population.
authors.affiliation: Department of Internal Medicine, Faculty of Medicine and Biomedical Sciences, University of Yaounde I, Yaounde, Cameroon. sobngwieugene@yahoo.fr.
authors.forename: Eugene
authors.initials: E
authors.lastname: Sobngwi
authors.forename: Andre-Pascal
authors.initials: AP
authors.lastname: Kengne
authors.forename: Justin B
authors.initials: JB
authors.lastname: Echouffo-Tcheugui
authors.forename: Simeon
authors.initials: S
authors.lastname: Choukem
authors.forename: Joelle
authors.initials: J
authors.lastname: Sobngwi-Tambekou
authors.forename: Eric V
authors.initials: EV
authors.lastname: Balti
authors.forename: Mark S
authors.initials: MS
authors.lastname: Pearce
authors.forename: Valentin
authors.initials: V
authors.lastname: Siaha
authors.forename: Aissa S
authors.initials: AS
authors.lastname: Mamdjokam
authors.forename: Valery
authors.initials: V
authors.lastname: Effoe
authors.forename: Eric
authors.initials: E
authors.lastname: Lontchi-Yimagou
authors.forename: Oliver T
authors.initials: OT
authors.lastname: Donfack
authors.forename: Barbara
authors.initials: B
authors.lastname: Atogho-Tiedeu
authors.forename: Philippe
authors.initials: P
authors.lastname: Boudou
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Gautier
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Mbanya
mesh_terms: D000328:Adult; D017954:Africa South of the Sahara; D044383:Black People; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000175:diagnosis* / Q000208:ethnology; D005215:Fasting / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D015309:Glucose Clamp Technique; D006801:Humans; D007328:Insulin / Q000008:administration & dosage / Q000097:blood* / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology; D011379:Prognosis; D055105:Waist Circumference; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D007328:Insulin
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