What Causes Tiredness, Increased Sensation Of Muscle Strain During Workouts And Leg Cramps While On Atorvastatin?

I currently take a statin, Atorvastatin for high cholesterol. The dosage is 20mg per day, once a day. My last blood work showed an elevation in blood sugar. I feel more tired than usual and workouts seem to cause an elevated number of muscle strains including cramps in my legs. Symptoms or old age (58)?