title: Feedback inhibition of insulin secretion and insulin resistance in polycystic ovarian syndrome with and without obesity.
abstract: Hyperinsulinemia/insulin resistance is a well-known feature of polycystic ovarian (PCO) syndrome. In this study, the comparative roles of the peripheral tissues and the pancreatic beta-cells in its pathogenesis were evaluated. We determined basal serum C-peptide values (index of insulin secretion) and in vivo insulin action on peripheral glucose utilization (by the euglycemic hyperinsulinemic clamp technique) in obese (n = 5) and nonobese (n = 5) PCO women compared to obese (n = 5) and nonobese (n = 5) normal ovulatory women. During the clamp, feed-back inhibition of insulin on insulin secretion was studied by C-peptide percentage suppression. Serum C-peptide basal values did not differ significantly between the four groups. Insulin stimulated glucose utilization, expressed as M-value, was significantly decreased in both PCO groups compared to normal ovulatory women (p < 0.005). The metabolic clearance rate of glucose (MCR) and insulin (M/I) had the same behaviour. No differences were found between M, MCR and M/I values and the two groups of PCO subjects (obese/nonobese). The C-peptide percentage suppression was similar in all the groups. We conclude that PCO women have a significant insulin resistance that is independent of obesity, while basal and insulin-inhibited insulin secretion do not differ from normal-cycle subjects.
authors.affiliation: Divisione di Endocrinologia e Malattie del Ricambio, Policlinico Universitario Paolo Giaccone, Palermo, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Sinagra
authors.forename: A M
authors.initials: AM
authors.lastname: Scarpitta
authors.forename: M
authors.initials: M
authors.lastname: Brigandì
authors.forename: G
authors.initials: G
authors.lastname: D'Acquisto
mesh_terms: D000328:Adult; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology*; D000078790:Insulin Secretion; D009765:Obesity / Q000150:complications / Q000378:metabolism*; D011085:Polycystic Ovary Syndrome / Q000150:complications / Q000378:metabolism*
chemical_list: D007328:Insulin