Women with polycystic ovarian syndrome ( PCOS ) have decreased growth hormone ( GH ), which can increase visceral adiposity ( VAT ) and impair vascular function.
GH releasing hormone, a dipeptidyl peptidase-4 ( DPP4 ) substrate, stimulates GH secretion.
Researchers have tested the hypothesis that DPP4 inhibition increases growth hormone and improves glucose levels and vascular function in women with PCOS.
Eighteen women with PCOS participated in a double-blinded, cross-over study. They received Sitagliptin ( Januvia ) 100 mg versus placebo daily for one month separated by an eight-week washout.
During each treatment, women underwent a 75-gram oral glucose tolerance test ( OGTT ), assessment of vascular function and body composition.
Overnight GH secretion was assessed via venous sampling every 10 minutes for 12 hours and analyzed using an automated deconvolution algorithm.
During OGTT, Sitagliptin has increased GLP-1 ( p less than 0.001 ), early insulin secretion ( from mean insulinogenic index 1.9±1.2 ( SD ) to 3.2±3.1; p=0.02 ) and decreased peak glucose ( mean -17.2 mg/dL [ 95% CI -27.7, -6.6 ]; p less than 0.01).
At one month, Sitagliptin has decreased visceral adiposity ( from 1141.9±700.7 to 1055.1±710.1 g; p=0.02 ) but did not affect vascular function.
Sitagliptin increased GH half-life ( from 13.9±3.6 to 17.0±6.8 min, N=16; p=0.04 ) and interpulse interval ( from 53.2±20.0 to 77.3±38.2 min, N=16; p less than 0.05 ) but did not increase mean overnight GH ( p=0.92 vs. placebo ).
In conclusion, Sitagliptin has decreased the maximal glucose response to oral glucose load and visceral fat.
Sitagliptin did not increase overnight GH but increased GH half-life and the interpulse interval. ( Xagena )
Devin JK et al, J Clin Endocrinol Metab 2019;Epub ahead of print