INS and polycystic ovary syndrome: In addition, FPG and fasting insulin showed a significant reduction after three months.[33]The effect of metformin on non-obese PCOS was also investigated in an another study by Morin-Papunen et al. They found a significant reduction in BMI, WHR, FPG and fasting insulin after three months of therapy with metformin, while the reduction in insulin sensitivity index was significant.