Lipitor Was My First Chol. Medicine More Than 10 Years

Lipitor was my first chol. medicine more than 10 years ago. I managed a credit union and got to where I would have to go in early to get complicated matters completed because my brain just would not function after early afternoon. I've been through Vytorian, Zocor, and several others and have been on simvustatin 40 mg. for several years now. I am 81 yrs. old,Wt. 130, blood pressure good, diabetic, on insulin, and my total chol 168, HDL 55, LDL 87, Trig, 156. My dr. wants me to go on atorvastatin 40mg. I have always felt Lipitor caused my diabetes and fear it's memory side effect. What do you suggest.