title: Proinsulin and age in general population.
abstract: OBJECTIVE
  The objective of this study was to assess the relationship between fasting proinsulin (PI) and age in general population and to determine whether there are differences regarding this association in obese and non-obese persons.
  
  
  METHODS
  A random population-based sample (n=656) of Romanians (26-80 years) living in Bucharest, Romania was studied; 432 persons had diabetes and they were not analyzed in this paper. Circulating levels of fasting plasma glucose (FPG), fasting plasma insulin (FPI), fasting plasma proinsulin (FPP), fasting plasma C-peptide, HbA1c, lipid profile, creatinine, urea were measured. The homeostasis model assessment of insulin resistance (HOMA-IR), HOMA-B, and Quicki index were also calculated.
  
  
  RESULTS
  For all participants proinsulin was the highest in the third quartile of the age group (59-67 years), with a median proinsulin of 5.8 pmol/L. Subsequently, proinsulin increased with age, from 2.6 pmol/L for participants aged 20-51 years, to 4.7 pmol/L for participants aged 51-59 years; proinsulin levels decreased in the upper quartile 4.8 pmol/L for those aged over 67 years. In sex-specific analyses, proinsulin increased with age for both men and women, except for those in the upper quartile. The prevalence of the obesity was 30.4% (n=68); obesity prevalence did not increase with age (p=0.26). Fasting proinsulin levels significantly increased with body mass index (BMI) category from lean (n=67, 2.9 pmol/L) to overweight (n=89, 4.5 pmol/L) and obese (n=69, 6.63 pmol/L) (p<0.0001).
  
  
  CONCLUSIONS
  Our study has demonstrated a close association between age and elevated proinsulin and proinsulin/insulin ratio in general population.
authors.affiliation: "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania ; Medas Clinic, Bucharest, Romania.
authors.forename: S
authors.initials: S
authors.lastname: Ateia
authors.affiliation: "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania.
authors.forename: E
authors.initials: E
authors.lastname: Rusu
authors.affiliation: "Titu Maiorescu" University, Bucharest, Romania.
authors.forename: V
authors.initials: V
authors.lastname: Cristescu
authors.affiliation: Emergency Hospital Călărași, Romania.
authors.forename: G
authors.initials: G
authors.lastname: Enache
authors.affiliation: "Nicolae Paulescu" National Institute of Diabetes, Nutrition and Metabolic Diseases, Bucharest, Romania.
authors.forename: D M
authors.initials: DM
authors.lastname: Cheța
authors.affiliation: "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania.
authors.forename: G
authors.initials: G
authors.lastname: Radulian
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood; D011384:Proinsulin / Q000097:blood*
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D011384:Proinsulin
keywords: C-peptide; aging; insulin resistance; obesity; proinsulin