Tadalafil is known to increase insulin sensitivity
If you visit this page: https://www.webmd.com/drugs/2/drug-77875/tadalafil-oral/details, then click the "interactions" link and scroll down to the bottom, you can enter each specific drug you are taking to check for interactions. I didn't see anything particularly concerning; however, you should talk with your doctor about your very low blood sugar. It might not be related to the tadalafil, but if I were you, I would discontinue using it until your doctor can run some tests.