Is Oxybutynin Advisable For Overactive Bladder?

My sister has MS and is taking Oxybutynin for overactive bladder she asked me to check on-line It is taken to help my urine fregency. I had taken it before and it seem then as it was effecting my own sugar level. As if I didn t eat for days and I was very weak. Our mom and myself was Type 2, she is not yet diabetic , she is 63.