title: HOMA-IR is associated with significant angiographic coronary artery disease in non-diabetic, non-obese individuals: a cross-sectional study.
abstract: Insulin resistance is a major component of metabolic syndrome, type 2 Diabetes Mellitus (T2DM) and coronary artery disease (CAD). Although important in T2DM, its role as a predictor of CAD in non-diabetic patients is less studied. In the present study, we aimed to evaluate the association of HOMA-IR with significant CAD, determined by coronary angiography in non-obese, non-T2DM patients. We also evaluate the association between 3 oral glucose tolerance test (OGTT) based insulin sensitivity indexes (Matsuda, STUMVOLL-ISI and OGIS) and CAD. We conducted a cross-sectional study with 54 non-obese, non-diabetic individuals referred for coronary angiography due to suspected CAD. CAD was classified as the "anatomic burden score" corresponding to any stenosis equal or larger than 50 % in diameter on the coronary distribution. Patients without lesions were included in No-CAD group. Patients with at least 1 lesion were included in the CAD group. A 75 g oral glucose tolerance test (OGTT) with measurements of plasma glucose and serum insulin at 0, 30, 60, 90 and 120 min was obtained to calculate insulin sensitivity parameters. HOMA-IR results were ranked and patients were also categorized into insulin resistant (IR) or non-insulin resistant (NIR) if they were respectively above or below the 75th percentile (HOMA-IR > 4.21). The insulin sensitivity tests results were also divided into IR and NIR, respectively below and above each 25th percentile. Chi square was used to study association. Poisson Regression Model was used to compare prevalence ratios between categorized CAD and IR groups.
  
  
  RESULTS
  Fifty-four patients were included in the study. There were 26 patients (48 %) with significant CAD. The presence of clinically significant CAD was significant associated with HOMA-IR above p75 (Chi square 4.103, p = 0.0428) and 71 % of patients with HOMA-IR above p75 had significant CAD. Subjects with CAD had increased prevalence ratio of HOMA-IR above p75 compared to subjects without CAD (PR 1.78; 95 % CI 1.079-2.95; p = 0.024). Matsuda index, Stumvoll-ISI and OGIS index were not associated with significant CAD. We concluded that, in patients without diabetes or obesity, in whom a coronary angiography study is indicated, a single determination of HOMA-IR above 4.21 indicates increased risk for clinical significant coronary disease. The same association was not seen with insulin sensitivity indexes such as Matsuda, Stunvoll-ISI or OGIS. These findings support the need for further longitudinal research using HOMA-IR as a predictor of cardiovascular disease.
authors.affiliation: Cardiology Division, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Márcio
authors.initials: M
authors.lastname: Mossmann
authors.affiliation: Cardiology Division, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Marco V
authors.initials: MV
authors.lastname: Wainstein
authors.affiliation: Cardiology Division, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Sandro C
authors.initials: SC
authors.lastname: Gonçalves
authors.affiliation: Cardiology Division, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Rodrigo V
authors.initials: RV
authors.lastname: Wainstein
authors.affiliation: Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Gabriela L
authors.initials: GL
authors.lastname: Gravina
authors.affiliation: Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Marlei
authors.initials: M
authors.lastname: Sangalli
authors.affiliation: Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Francine
authors.initials: F
authors.lastname: Veadrigo
authors.affiliation: Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Roselene
authors.initials: R
authors.lastname: Matte
authors.affiliation: Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Rejane
authors.initials: R
authors.lastname: Reich
authors.affiliation: Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Porto Alegre, 90035-903 Brazil.
authors.forename: Fernanda G
authors.initials: FG
authors.lastname: Costa
authors.affiliation: Internal Medicine Department, Hospital de Clínicas de Porto Alegre and Programa de Pós-Graduação em Medicina: Ciências Médicas, Universidade Federal do Rio Grande do Sul, Ramiro Barcellos 2350, Room 700, Porto Alegre, 90035-903 Brazil.
authors.forename: Marcello C
authors.initials: MC
authors.lastname: Bertoluci