Insulin hypersecretion during oral or intravenous glucose tolerance test (OGTT, ivGTT) was described previously in women with polycystic ovary syndrome (PCOS). Little attention was given to the regulation of insulin secretion in these subjects. We aimed to study the secretion of incretins (glucose-dependent insulinotropic polypeptide, GIP, glucagon-like peptide 1, GLP-1), during OGTT in normoglucose-tolerant PCOS women.
After signing written informed consent approved by the local Ethical Committee, women with PCOS (n=21,age 25.8±4.1 years, BMI 21.6±1.7 kg/m2) and control healthy women (CT n=13, 28.5±7.2 years, 20.3±2.5 kg/m2) underwent OGTT with sampling for blood glucose, insulin, C-peptide, total GIP and active GLP-1. Insulin sensitivity was assessed in fasting (QUICKI) and in dynamic conditions (OGIS; ml/min per m2). Two-sample t-tests or repeated measures ANOVA followed by LSD were done. Values are given as mean±S.D.
Basal glucose, insulin and C-peptide did not differ between PCOS and CT. Similarly, stimulated glucose and insulin did not differ significantly between PCOS and CT as well as QUICKI and OGIS. During OGTT, PCOS had higher levels of C-peptide than CT irrespective time (ANOVA PCOS vs CT P<0.05, PCOS vs time interaction P=0.76), higher AUCCP (370±113 vs 325±104 nmol/180 min P=0.05) along with higher levels of GIP (ANOVA PCOS vs CT P<0.001; PCOS vs time P=0.76) and with higher AUCGIP (39 250±16 680 vs 29 890±7000 pg/180 min; P=0.06). Total active GLP-1 was not higher in PCOS; however, GLP-1 pattern of PCOS was significantly different from CT being lower at 180 min (ANOVA PCOS vs time P<0.008).
In conclusion, enhanced insulin secretion in normotolerant women with PCOS is associated to a general augmentation of GIP and to a late-phase decrease of GLP-1. Elevated incretin secretion and the concomitant insulin hypersecretion could be early markers of not yet fully expressed prediabetic state.
Supported by Ministry of Health of Czech Republic, grant NR 8759-3.
03 - 07 May 2008
European Society of Endocrinology