Basic and Meal Stimulated Plasma GIP Levels are Higher in Lean PCOS Women with FAI over 5

Objective: Glucose dependent insulinotropic peptide (GIP) belongs to the incretins which are responsible for 70% of the insulin release after oral glucose intake. Its impaired secretion was noted in several conditions involving insulin resistance, including polycystic ovary syndrome (PCOS), known as the state with increased testosterone level. This paper considers a possible relationship between the free androgen index (FAI) and basal as well as meal stimulated level of GIP in lean women affected by PCOS. To our knowledge, no previous study has evaluated the matter so far.

Design: cross-sectional study

Methods: 50 age-matched lean women (BMI=20.76±1.83) were enrolled to the study and divided into 2 groups. Patients with phenotype with FAI<5 were classified as group 1, PCOS patients with FAI>5 formed group 2. All subjects underwent standard meal test. Serum GIP concentration was determined both at fasting and at 60 min of the test. Calculations were carried out using Statistica 10.

Results: Mann-Whitney test indicated a statistically significant difference in medians values of GIP plasma levels between groups on fasting (36.4 pg/ml vs. 59.6 pg/ml; p=0.0007) and at 60 min after meal test (50.1 pg/ml vs. 72.5 pg/ml; p=0.006). Spearman test indicated significant positive correlation between FAI and GIP levels at 0' and 60' in total study population (0':R=0.37;p=0.008; 60':R=0.28; p=0.049).

Conclusion: Excess androgen activity might be a factor contributing to alter secretion of incretins in lean PCOS women. However it could not be ruled out that it is also possible that increased GIP levels might induce hyperandrogenemia in PCOS. An increased GIP levels may induce hyperinsulinemia and play an additive to insulin resistance role in progression to diabetes mellitus type 2 (DMT2).