title: ALTERED CIRCULATING LEVELS OF RETINOL BINDING PROTEIN 4 AND TRANSTHYRETIN IN RELATION TO INSULIN RESISTANCE, OBESITY, AND GLUCOSE INTOLERANCE IN ASIAN INDIANS.
abstract: OBJECTIVE
  Retinol binding protein 4 (RBP4) has been implicated in metabolic disorders including type 2 diabetes mellitus (T2DM), but few studies have looked at transthyretin (TTR) with which RBP4 is normally bound to in the circulation. We report on the systemic levels of RBP4 and TTR and their associations with insulin resistance, obesity, prediabetes, and T2DM in Asian Indians.
  
  
  METHODS
  Age-matched individuals with normal glucose tolerance (NGT, n = 90), impaired glucose tolerance (IGT, n = 70) and T2DM (n = 90) were recruited from the Chennai Urban Rural Epidemiology Study (CURES). Insulin resistance was estimated using the homeostasis model assessment of insulin resistance (HOMA-IR). RBP4 and TTR levels were measured by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  Circulatory RBP4 and TTR levels (in μg/mL) were highest in T2DM (RBP4: 13 ± 3.9, TTR: 832 ± 310) followed by IGT (RBP4: 10.5 ± 3.2; TTR: 720 ± 214) compared to NGT (RBP4: 8.7 ± 2.5; TTR: 551 ± 185; P<.001). Compared to nonobese NGT individuals, obese NGT, nonobese T2DM, and obese T2DM had higher RBP4 (8.1 vs. 10.6, 12.1, and 13.2 μg/mL, P<.01) and TTR levels (478 vs. 737, 777, and 900 μg/mL, P<.01). RBP4 but not TTR was significantly (P<.001) correlated with insulin resistance even among NGT subjects. In regression analysis, RBP4 and TTR showed significant associations with T2DM after adjusting for confounders (RBP4 odds ratio [OR]: 1.107, 95% confidence interval [CI]: 1.008-1.216; TTR OR: 1.342, 95% CI: 1.165-1.547).
  
  
  CONCLUSIONS
  Circulatory levels of RBP4 and TTR showed a significant associations with glucose intolerance, obesity, T2DM and RBP4 additionally, with insulin resistance.
authors.forename: Gautam Kumar
authors.initials: GK
authors.lastname: Pandey
authors.forename: Jayashree
authors.initials: J
authors.lastname: Balasubramanyam
authors.forename: Mahalingam
authors.initials: M
authors.lastname: Balakumar
authors.forename: Mohan
authors.initials: M
authors.lastname: Deepa
authors.forename: Ranjit Mohan
authors.initials: RM
authors.lastname: Anjana
authors.forename: Shiny
authors.initials: S
authors.lastname: Abhijit
authors.forename: Anand
authors.initials: A
authors.lastname: Kaviya
authors.forename: Kaliyaperumal
authors.initials: K
authors.lastname: Velmurugan
authors.forename: Priya
authors.initials: P
authors.lastname: Miranda
authors.forename: Muthusamy
authors.initials: M
authors.lastname: Balasubramanyam
authors.forename: Viswanathan
authors.initials: V
authors.lastname: Mohan
authors.forename: Kuppan
authors.initials: K
authors.lastname: Gokulakrishnan
mesh_terms: D000328:Adult; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D018149:Glucose Intolerance / Q000097:blood*; D006801:Humans; D007194:India; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*; D011228:Prealbumin / Q000378:metabolism*; D011236:Prediabetic State / Q000097:blood*; D054839:Retinol-Binding Proteins, Plasma / Q000378:metabolism*
chemical_list: D011228:Prealbumin; C101326:RBP4 protein, human; D054839:Retinol-Binding Proteins, Plasma